Looking at the Surface of the : Descartes on Visual Sensory

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of in the Graduate School of The Ohio State University

By

Matthew Christopher McCall

Graduate Program in Philosophy

The Ohio State University

2017

Dissertation Committee:

Lisa Downing, Advisor

Julia Jorati

Lisa Shabel

Copyrighted by

Matthew Christopher McCall

2017

Abstract

One of the most defining features of René Descartes’ philosophy is the and degree of his dualism. As conventional readings go, Descartes neatly divides into two radically distinct types of substances—mind and body—and never the two shall meet.

I argue, however, that Descartes does not split the mind from body as cleanly as conventional readings might think, that the two metaphysical hemispheres are not entirely separate. There is a bridge linking the two together, and the roadmap for discovery is found in Descartes’ of sensory perception.

Descartes’ views on sensory perception is the most apt topic in which to seek an of the relationship between mind and body because, in general, it requires some about how immaterial are informed by material bodies; that is, the topic demands that Descartes hypothesize about how —which he considers exclusive to —can be of things wholly distinct in kind, things that are essentially material. Throughout his writings, Descartes pays most to visual sensory perception, and so I follow in suit. Moreover, I concentrate on visual shape perception because, as I argue, understanding this aspect of Descartes’ philosophy leads to insights about the precise relationship between mind and body.

To give a feel for the overall shape of my reading, consider “veil of perception” interpretations of Descartes. Such readings understand Descartes as wedging a “third

ii thing” between perceivers and the perceived , standardly ascribing the “third thing” to the mind itself. On such readings of Descartes, sensory access to the physical world is mediated by mental images. So, according to these readings, one sees an of a tree, but not the tree itself. According to the reading of Descartes I offer, however, the veil is sheerer than previously . For I argue that the “third thing” bridging perceivers with the perceived belongs to bodily substance. In particular, I argue that minds directly perceive a part of the brain. This view has ramifications for Descartes’ dualism because, in order to make of exactly how minds are directly aware of their brain, Descartes posits a unique ontological item shared between mind and body, thereby rejecting the absolute dualism supposed by more conventional readings.

My for these claims rely chiefly on interpreting Descartes as adhering to the presentation thesis, a thesis claiming, in general, that minds directly attend to a brain state. The first three chapters of the dissertation are devoted to showing how the presentation thesis fits with and can be derived from the full range of Descartes’ writings.

In the final chapter I argue that the presentation thesis influences , in part, to locate the “wedge” of his theory of sensory perception in .

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Light is the source of .

To my mother.

iv

Acknowledgments

Descartes might have us believe that philosophy is best done in solitude. This has not been my , though. This dissertation would be little more than a collection of wandering were it not for the sustained , emotional, and financial support of the OSU philosophy department. I especially thank my committee advisor,

Lisa Downing. Any depth and clarity found within the following pages is no doubt a product of her invaluable guidance. I also thank Julia Jorati and Lisa Shabel. Both are models of the intellectual and interpretive rigors demanded of a good historian, and so I am fortunate not only to have them on my dissertation committee but also to have pursued coursework in the of philosophy under their instruction. Additionally, without the bureaucratic and financial clarity of the OSU philosophy staff, I certainly would not have found my way through the maze of policy and procedure. Thus, I give many thanks to Debbie Blickensderfer, Michelle Brown, Miranda Johnson, and Sue

O’Keeffe for getting me through the entanglements of paper work and, more importantly, for inviting me to sit in their presence when I sought relief from philosophical entanglements.

I would never have out to write a dissertation in the history of philosophy if not for certain in my own history, however. I extend gratitude to Walter Ott for sparking my interest in Nicolas Malebranche and early modern during my v at Virginia Tech. I also thank Christopher Martin for his many contributions to my undergraduate at the University of Saint Thomas (and especially his willingness to privately tutor me in Wittgenstein’s philosophy). But without the kindness, compassion, and discipline provided by and exemplified in my first philosophy instructor,

I do not know if I would have thought myself capable of pursuing academics at all. Thank you, Mr. Spedale, for giving me Aquinas instead of detentions (although you gave me plenty of those too) and for giving me your confidence when I could not find my own.

In many ways, the intellectual challenge of pursuing a doctorate has been outmatched by the challenge of living apart from my . But this difficulty was made less so by the genuine camaraderie of department members. I thus thank the many graduate students in the OSU philosophy department for my family away from home. I am especially grateful to Jerilyn Tinio for her and enthusiasm about all things . Without the companionship and encouragement so frequently given by her and Memu the plenum would have been noticeably vacuous.

To my family at home, I am blessed to have grown up among such joy and laughter, and am equally blessed to return to it every Christmas. I thank my family for showing me the art of a well-lived life. To these names I give endless gratitude: the

Castillos, the Garcias, the Livingstons, the Martinezes, the McCalls, and the Ozunas. But joy is so often mixed with sadness, as any family must come to learn. We have lost two of our own while I have been away, and so I dedicate my work to their . Uncle

Ramon, you were right, was the only worth buying from the shelf that day, as you well knew, being yourself an eudaimonian model in many ways.

Grandma, we gathered in a circle around you and prayed the Hail Mary as you lay dying in vi the home built of your generosity. You taught me then—as you always did—that makes life eternal.

I do not have biological siblings, but I nonetheless have a brother in and origin. Anthony Castillo, you are my brother, and always be, come hell or high water

(and being Houstonians we know quite a bit about high water). You and your mother are part of who I am, and so I additionally dedicate this to the memory of your loving mother and my loving aunt, Janie Castillo. And, of course, where would I be without those other

“brothers” that have so enriched my life? Every weekday at three o’clock for the past three years, Joshua Jacobs and Gabriel Schneider have called to ask if my dissertation is completed and then proceeded to chat with me about worth anybody’s time.

Without their daily nonsense counterbalancing the rigors of academia, I do not know if I would have finished this dissertation with my mind intact. Much love to both of them

(and our good friend “Ima Ima”). To Juan Miguel Garcia, who so long ago discussed

Wittgenstein with me as the IMAX projector rolled noisily in the background, thank you for showing me that academic degrees are not necessary for being a good philosopher. I also thank David Chavez and Alex Ng Ng for “believing it” through all these years. And to my many friends that I have made on this academic journey spanning Texas, Virginia, and

Ohio, thank you for listening, thank you for caring, and thank you for the history we created together.

Dad, you may have never been told so, but you are a philosopher. I know this because I see more of you in me as I get older. I see myself combating hardship with hearty laughter, valuing the discipline and reward of hard work, and finding contentment where others might easily see misfortune. From you I have learned that there is a hidden vii joy in so many things, and one need only abandon their own resistance in order to experience it. Daoists would call this a life of “wu-wei,” but, as you well know, this says too much. For, simply, “it is what it is.”

Mom, it was not easy for us when I was young. But, above all else, you made sure to give me a proper education. I realize now the degree of sacrifice you made in choosing to send me to Catholic schools. Your was—and continues to be—the I made it this far. My education is the greatest gift you gave to me, and you gave it to me out of a selfless and magnificent love. And so, in return, I give my work to you, knowing that the tireless effort, dogged dedication, and patient that went into these pages is but the fruition of what you so firmly and tenderly planted many years ago. I certainly did “keep on trucking,” and, in no small way, you were the spark that kept me moving.

Thank you, Mom. I love you.

Finally, to Philip 2420, you are a cat, and so, by Descartes’ reckoning, you do not understand a word I’m saying—for you are but an automaton. But I just want to say that, at least to me, you are no automaton. Automatons surely cannot provide the depth of friendship that you have given me over the years. And so I say this to you, Phil: we did it, mijo! We completed this dissertation! Now let’s eat some dinner and watch TV.

viii

Vita

2001 ...... Saint Pius X High School

2005 ...... B.A. Philosophy, , University of

Saint Thomas, Houston, summa cum laude

2009 ...... M.A. Philosophy, Virginia Polytechnic

Institute

2017 ...... Ph.D. Philosophy, The Ohio State University

Publications

2011. “The Blob Necessitates.” In Philip K. Dick and Philosophy: Do Androids have Kindred

Spirits, 175 – 184, edited by D.E. Wittkower. Chicago: Open House.

Fields of Study

Major Field: Philosophy

ix

Table of Contents

Abstract ...... ii

Acknowledgments...... v

Vita ...... ix

List of Figures ...... xii

Introduction ...... 1

Chapter 1: Illumination ...... 18

Section 1 ...... 18

Section 2 ...... 24

Section 3 ...... 28

Chapter 2: Looking at the Surface of the Mind ...... 42

Section 1 ...... 43

Section 2 ...... 49

Section 3 ...... 61

Section 4 ...... 67

Section 5 ...... 83 x

Chapter 3: Combating the Eyes in our Brain ...... 87

Section 1 ...... 89

Section 2 ...... 96

Section 3 ...... 100

Section 4 ...... 114

Section 5 ...... 125

Chapter 4: the Divine Pineal Gland ...... 130

Section 1 ...... 131

Section 2 ...... 134

Section 3 ...... 143

Bibliography ...... 149

xi

List of Figures

Figure 1. Phenomenal Shape...... 3

Figure 2. Alhazen's Camera Obscura ...... 19

Figure 3. Transmission ...... 21

Figure 4. Light Deflection...... 31

Figure 5. Directional Configurations ...... 32

Figure 6. Wave Propagation ...... 35

Figure 7. Shape Transmission ...... 36

Figure 8. The Pineal Gland ...... 44

Figure 9. Pin Art Toy Model...... 47

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Introduction

One of the most defining features of René Descartes’ philosophy is the nature and degree of his dualism. As conventional readings go, Descartes neatly divides reality into two radically distinct types of substances—mind and body—and never the two shall meet.

I argue, however, that Descartes does not split the mind from body as cleanly as conventional readings might think, that the two metaphysical hemispheres are not entirely separate. There is a bridge linking the two, and the roadmap for discovery is found in Descartes’ theory of sensory perception.

Descartes’ view on sensory perception is the most apt topic in which to seek an understanding of the relationship between mind and body because, in general, it requires some explanation about how immaterial souls are informed by material bodies; that is, the topic demands that Descartes hypothesize about how perceptions—which he considers exclusive to minds—can be of things wholly distinct in kind, things that are essentially material. Throughout his writings, Descartes pays most attention to visual sensory perception, and so I follow in suit. Moreover, I concentrate on visual shape perception because, as I argue, understanding this aspect of Descartes’ philosophy leads to insights about the precise relationship between mind and body.

1

To give a feel for the overall shape of my reading, consider “veil of perception” interpretations of Descartes.1 Such readings understand Descartes as wedging a “third thing” between perceivers and the perceived object, standardly ascribing the “third thing” to the mind itself.2 On such readings of Descartes, sensory access to the physical world is mediated by mental images. So, according to these readings, one sees an idea of a tree, but not the tree itself. According to the reading of Descartes I offer, however, the veil is sheerer than previously thought. I argue that the “third thing” bridging perceivers with the perceived belongs to bodily substance. In particular, I argue that it belongs to a part of the brain. This view has ramifications for Descartes’ dualism because, in order to make sense of exactly how minds are directly aware of their brain, Descartes posits a unique ontological item shared between mind and body, thereby rejecting the absolute dualism supposed by more conventional readings.

To show readers that there is a genuine debate about where this “wedge” is located

(especially when it comes to of shape) and, thus, reason to entertain alternative renderings of Descartes’ dualism, I now introduce philosophical notions central to the concerns here and briefly discuss pivotal passages from Descartes’ corpus.

Accordingly, I will frequently use the phrases “phenomenal shape” and “perceived shaped” throughout. These two taglines (and their cognates) pick out particular

1 I borrow this rendering of the “veil of perception” as including a “third thing” from Kurt Smith. See Smith 2013, sec. 4. The slogan “veil of perception” originates from Jonathan Bennet’s work on Locke. See Bennet 1971, 69. 2 Commentators vary widely on what this “wedge” amounts to and for Descartes’ endorsement of it. Nonetheless, for examples of those who seeing the “wedge” (broadly conceived) as mental in nature, see Atherton,1990, 19 – 22; Kenny 1968, 222; Hatfield 1992, 354; Hatfield and Epstein 1979, 377; Maull 1978, 260; Machamer and McGuire 2009, 214 – 215; Newman 2009, 134; Schmaltz 2008, 159 – 160; Rozemond 1998, 173 – 174; Rorty 1992, 371 – 374; Simmons 2003 A and B, 556 – 559 and 420 en 8, respectively ; Wilson 1978, 1990, 1999, 104, 8, and 23, respectively; and Wolf-Devine 1993 and 2000B, 3 and 558, respectively. 2 characteristics of visual phenomenal experience. To give a better grasp on what I mean by the terms, consider the image within the region below:

Figure 1. Phenomenal Shape

If I were to ask which two are observable within the region of Figure 1, the majority of observers would reply ‘black’ and ‘white’. The colors ascribed to the region are the phenomenal characteristics corresponding to the names ‘black’ and ‘white.’ Now, if I were to ask which shape the region contains, most observers would say ‘circle’, and so experience the phenomenal character of ‘circle’—an instance of “phenomenal shape” or

“perceived shape.” But here is a trickier question: is the phenomenal characteristic of

‘circle’ just the phenomenal characteristic of ‘black’ and ‘white’ arranged in a ‘circular’ way, or is it somehow more? This is an important question for Descartes because, for him, phenomenal characteristics pair off with certain ways of existing and types of existents. In other words, for Descartes, the phenomenal influences the ontological.

Descartes is a substance-mode ontologist. Understood as an ontological item, substance exists independently of anything else—it is the fundamental and discrete unit

3 of .3 Modes are dependent existents. They are modifications of or ways in which substances exist. And, as is commonplace knowledge, Descartes is a substance dualist.

There are two—and only two—kinds of substances: bodily substance and mental substance. Each is characterized by a principal attribute, or a “principal which constitutes its nature and , and to which all its other properties are referred” (AT

VIIIA 25 / CSM 1 210).4 Principal attributes are the basic feature that all modes of a type of substance have in common, and of them Descartes writes, “ else which can be attributed to body presupposes , and is merely a mode of an extended thing; and similarly, whatever we find in the mind is simply one of the various modes of thinking” (AT VIIIA 25 / CSM 1 210). The principal attribute of bodily substance is extension, conceived broadly as breadth, width, and depth, while the principal attribute of mental substance is thought, the definition of which is discussed shortly.5 As traditionally understood, modes of thought, in and of themselves, are not extended and modes of body are not thoughts—the two classes are mutually exclusive.6 Thus, when I said earlier that the phenomenal influences the ontological, I gestured at the that phenomenal characteristics are candidates for ontological classification, that their

3 This of substance grants that, in a strict sense, God is the only genuinely independent metaphysical item, and so assumes that continued existence of created substances relies on God’s concurrence. I am relying on the of substance and mode found in the I, sections 51 – 58 (see AT VIIA 24 – 27 / CSM 1 210 – 212), and it is standardly assumed that Descartes changed his mind very little—if at all—about the basic between substance and mode. 4 I use the following abbreviations for English translations of Descartes’ works: AT = Oeuvres de Descartes, edited by Charles Adam and Paul Tannery. CSM = The Philosophical Writings of Descartes, Vols. 1 and 2, translated by John Cottingham, Robert Stoothoff, and Dugald Murdoch. CSMK = The Philosophical Writings of Descartes: the Correspondence, translated by John Cottingham, Robert Stoothoff, Dugald Murdoch, and . G = The World and Other Writings, edited and translated by Stephen Gaukroger. (Note: when quoting from the Treatise on Man I use Gaukroger’s translation unless noted otherwise). O = Discourse on Method, Optics, , and , translated by Paul J. Olscamp. (Note: when quoting from the Optics I use Olscamp’s translation unless noted otherwise). 5 To further draw out the distinction between modes and principal attributes, the former are existent (albeit dependent) ontological items, whereas the latter more akin to general adequately describing the range of possible modes. 6 Although, as I argue in Chapter 2, there is a special ontological item that breaks the mold on this point. 4 ontological status falls among either modes of body or modes of mind (but not both, according to traditional readings). And questions about ontological status is a central concern throughout this dissertation, for the ontological status of sensory phenomenal (experiences like those in Figure 1) is a murky affair in Descartes’ writings.

In the Descartes provides examples of modes of body and modes of mind. He writes that,

For example, shape is unintelligible except in an extended thing; and is unintelligible except as motion in an extended ; while imagination, sensation and will are intelligible only in a thinking thing. By contrast, it is possible to understand extension without shape or movement, and thought without imagination or sensation, and so on; and this is quite clear to anyone who gives the his attention (AT IXB 25 / CSM 1 210).

This passage provides examples of modes proper to each type of substance. Notice that

Descartes lists shape among modes of body but sensation among modes of mind. One might, then, read Descartes as giving a forthright view on the of what one perceives in phenomenal shape. For if shape is a mode of extended bodies and sensation that of minds, Descartes appears to assert something commonsensical: the experience of phenomenal shape is a visual sensory experience in which minds are directly aware of bodily modes. The mind, as it were, “looks” directly at an extended bit of matter.

But commonsense reaches its boundaries once one considers passages from

Descartes’ writings on physiology. Most notably, in one such passage from his Treatise on

Man, after explaining that tiny “figures” or shapes form within the brain, Descartes writes that “...it is only the latter figures which should be taken to be forms or images which the rational united to this machine [the ] will consider directly when it imagines some object or perceives it by the ” (AT XI 176 - 177 / CSM 1 106 / G 149).

Descartes thus indeed appears committed to claiming that minds are directly aware of 5 bodily modes, but only insofar as minds are directly aware of shapes or figures in the brain.

Despite its lack of intuitive pull, I contend that this is Descartes’ considered view.

In saying this I thereby make a claim about Descartes’ view on the ontological status of perceived shape’s intentional object. The term ‘intentionality’ and its kind are not

Descartes’ own, so care should be taken in using them. I intend to use the terms in a minimally committing manner, as Allison Simmons does,

I mean to employ the term in a maximally inclusive way. To say that a is intentional is simply to say that it is of or about or directed to an object of some sort (be it a , a mental object, a concrete object, an abstract object, a , a state of affairs, or any other sort of object you fancy). It is not to say, more particularly, that the mental state possesses content (propositional content, informational content, conceptual content, representational content, or any other kind of content). It is not to say that the mental state is -apt or has satisfaction conditions. It is not to say that the mental state is capable of being directed to a non-existent object or that its object has a special sort of immanent inesse. I mean my use of intentionality to be neutral with respect to competing of intentionality, theories about its nature (Simmons 2009, 106).

But there should be at least one specification: Descartes is a substance-mode ontologist, and the relevant notion of intentionality here should reflect that fact. Accordingly, an intentional state is a perceptual mode of mind immediately directed at either a physical object (i.e. mode of body) or mental object (i.e. mode of mind), and my claim is that, in regards to visual shape perception, minds are directed at a mode of body (granting certain caveats explained in Chapter 2). Moreover, the intentional relation of “directed at,” at least as I use it, is not meant to indicate any action that minds engage in. Rather, the relation is basic, brute, and unanalyzable and, as such, is that by which sensory perception is made possible (among other types of perception).

My reading of Descartes thus generally asserts that the direct intentional object of perceived shape is a mode of body, it is a shape within the brain itself. But as I show in the body of the dissertation, Descartes’ take on the intentionality of perceived shape is

6 more specific, for he identifies the relevant brain shapes as configurations of small pressing against the surface of the pineal gland. Thus, since my rendering of intentionality suggests that brains directly “present” shapes to minds, I label it the

“presentation thesis,” and, considering the specifics of Descartes’ physiological views, I define the thesis as such: the direct intentional object of perceived shape is a created by particles emitted through the body of the pineal gland and onto the pineal gland’s surface.7

Defending the presentation thesis as Descartes’ considered view is among my main , and I have four broad motivations for doing so. First, I take myself as giving an accurate view of Descartes’ ontological classification of perceived shape’s direct intentional object (and, so, do not take myself as informing one about what Descartes should have said, or how his views stand in relation to contemporary concerns, or if

Descartes is right or wrong). As I hope to convince readers, the presentation thesis simply appears to be Descartes’ position from his earliest writings until his last.8

This very point about the thesis’ lifespan is a matter of scholarly debate, however.9

Thus, a second broad motivation is to show that Descartes did not change his mind about the presentation thesis. Rather, as I argue, the thesis in fact backgrounds much of his later philosophizing. Relatedly, scholars have debated about the internal consistency of

Descartes’ account of sensory perception. Thus, by providing a reading meant to span

7 Since I claim that minds directly attend to the brain, my reading aligns in a broad ways with commentators like Chignell 2009; Clarke 2003; MacKenzie 1990; Scholl 2005; Sepper 2009; Smith 2005; Yaldir 2009; and Vinci 1998. Labeling the view as involving a “presentation” to the mind is inspired by Wilson. See Wilson (1991), 294. 8 Nonetheless, even though I take my project to be largely interpretative, I occasion across instances in which I must speculate a bit in order to tie together Descartes’ varied commitments. 9 For example, see Machamer and McGuire 2009, 3 – 4, and Ott 2017, 100. 7

Descartes’ corpus, I aim to side against commentators viewing Descartes’ theory of sensory perception as hampered by inconsistencies.10

Third, I believe that the presentation thesis, at least in terms of structure, had heretofore unexamined influence on Nicolas Malebranche, one of the most radical

Cartesians of the early modern period. For, although forthrightly avowing Descartes’ dualism, Malebranche makes what appears, at least at first blush, a novel modification to the Cartesian view of intentionality in sensory perception: he locates the direct intentional object of perceived shape in God, in something external to minds. Although

Malebranche’s theological concerns are no doubt part of his motivation, reading Descartes as seriously committed to the presentation thesis sheds new light on this otherwise curious Cartesian modification.

Finally, taking the presentation thesis seriously prompts one to reconsider the nature of Descartes’ dualism, one of the more—perhaps most—prominent aspects of his philosophy. For in saying that minds are directly aware of their brains one is also saying that minds have direct perceptual access to the brain itself. But such access seems inscrutable—if not magical—were there no corresponding ontological link between these otherwise disparate substances. Thus, taking the presentation thesis as Descartes’ considered view requires one to tie mind and body closer together than traditionally thought.

But, as I hinted, endorsing the presentation thesis has its hurdles. Perhaps foremost, it might be worried that, as one commentator has put it, the view is simply

10 See, for example, Kenny 1968, 216 – 226; Wilson 1991, 294; and Wolf-Devine 1993, 5 – 6. 8

“intrinsically bizarre.” 11 Moreover, the presentation thesis simply appears naive and crude, especially in light of Descartes’ extraordinary intellectual prowess. As a general , I hope to assuage such worries by showing that the presentation thesis is but one facet of an intricate theory of sensory perception, a theory spanning across in , , and especially (or what is nowadays conceived of as natural ). Thus, once the presentation thesis is connected with the full breadth of Descartes’ views on sensory perception, readers should be able to see that it is an elegant means of pulling together diverse strands of thought.

Another type of problem confronting the thesis comes directly from Descartes’ own words. For example, in what is often taken as his explicit disavowal of the view,

Descartes writes in his Optics that it is not “as if there were yet other eyes in our brain” by which to inspect the brain itself. My reply to these worries, as readers will see in greater detail, is simply this: context . Passages like these (most prominent in Descartes’

Optics) ought not to be read in isolation since doing so is not adequately sensitive to

Descartes’ careful wording and overall . We will thus come to appreciate a certain dialectical sophistication within Descartes’ writings, a sophistication that can be easily misread if read too hastily.

A far more complex problem challenges my reading, however, and it is worth addressing up front and at some length. The problem can be glimpsed from remarks and vocabulary within Descartes’ Meditations on First Philosophy. In the Second Meditation

Descartes argues that one can know with that they are a thinking thing, that is, one can know that they are a mental substance capable of taking on particular modes of

11 See Wilson 1991, 294. 9 mind. Descartes expresses this point by questioning what “I” am. He states, “But what then am I? A thing that thinks. What is that? A thing that doubts, understands, affirms, denies, is willing, is unwilling, and also imagines and has sensory perceptions” (AT VII 28 /

CSM 2 19). Descartes’ inclusion of “sensory perceptions” here is significant because, as part of his famed methodical doubt, he supposes prior to making the above that bodies do not exist, therefore implying that one can experience phenomenal shape even if material substance fails to exist.12

Such thought gains further traction in the Sixth Meditation, where Descartes summarizes the Meditations’ main conclusions. In one such passage, Descartes describes sensory perception as “a passive for receiving and recognizing the of sensible objects” (AT VII 79 / CSM 2 55), and in a later passage states that a “given movement occurring in the part of the brain that immediately affects the mind produces just one corresponding sensation” (AT VII 87 / CSM 2 60). Defining sensory perception as the capacity to receive “ideas” and stating that “sensation” is an effect in the mind is a problem for the presentation thesis. These phrasings possibly imply that all intentional objects of visual sensory perception are modes of mind, in turn excising the intentional object of perceived shape from the brain. But these passages are a problem for the presentation thesis because, in large, the terms ‘idea’ and ‘sensation’ are systematically problematic within Descartes’ writings. Thus, I clarify from the outset how these two terms fit within my reading. I begin with ‘idea’.

In his earliest writings, Descartes identifies ‘ideas’ with movements and shapes in the brain. In the passage from the Treatise on Man cited earlier, we saw Descartes say that

12 It might be argued that even if phenomenal shape could be experienced without an attending body, this does not mean that this is actually what happens. To me, this is a legitimate reply, although, for the sake of , I leave it aside. 10 souls “directly consider” tiny “figures” in the brain. Immediately before making this claim, though, Descartes defines ‘idea’ in terms of figures, saying that ‘ideas’ are “only those

[figures] which are traced in the spirits on the surface of the [pineal] gland” (AT XI 176 -

177 / CSM 1 106 / G 149). His early definition of the term is boon for the presentation thesis, but, as we saw, his later uses of the term appear not to bode as well for my reading.

They suggests that, as one pair of commentators have put it, “ideas, understood in this

[later] general sense, are placed squarely within the disembodied mind” (Machamer and

McGuire 2009, 3).

As a general strategy throughout, I handle Descartes’ use of ‘idea’ on a case-by-case basis, examining, if needed, the relevance of the term’s to whatever passage is at hand. Nonetheless, there is a point worth noting about Descartes’ later use of the term that creates space for interpretations like mine. In his Second Replies, Descartes explicitly defines ‘idea’ in the following way:

I understand this term to mean the form of any given thought, immediate perception of which makes me aware of the thought. Hence, whenever I express something in words, and understand what I am saying, this very fact makes it certain that there is within me an idea of what is signified by the words in question. Thus it is not only the images depicted in the imagination which I call 'ideas'. Indeed, in so far as these images are in the corporeal imagination, that is, are depicted in some part of the brain, I do not call them 'ideas' at all; I call them 'ideas' only in so far as they give form to the mind itself, when it is directed towards that part of the brain (AT VII 160 / CSM 2 113).

This passage suggests that the varied uses of ‘idea’ need not stand in the way of Descartes endorsing the presentation thesis. Although it is clear that Descartes no longer wants to label images or figures in the brain as ‘ideas’ by the time he writes the Meditations, he nonetheless continues to maintain that minds are directly aware of certain brain states.

Accordingly, I do not take it as a pressing objection that Descartes uses ‘idea’ in a way that seems to locate them exclusively in minds because Descartes openly acknowledges that

11 his theory of ideas is consistent, in one way or another, with views like the presentation thesis. Thus, although ideas might be “placed squarely within the disembodied mind,” I do not take it as an immediate entailment that the direct intentional object of perceived shape must therefore belong to the mind as well.

Turning now to ‘sensation’, I first note that the term is also notoriously ambiguous within Descartes’ corpus. On some occasions, he treats it as synonymous with sensory perception generally conceived, as broadly referencing conscious awareness of any sensible qualities (i.e. phenomenal characteristic), thereby including both perceived and perceived shape in the term’s meaning. At other , however, he uses ‘sensation’ in a “strict sense.” But, as Kurt Smith notes, there is much grey area in this technical meaning as well. Smith identifies at least six different strict meanings, the first four of which show just how entangled the term is:

S1: ‘Sensation’ denotes a motion in the brain.

S2: ‘Sensation’ denotes an idea in the mind.

S3: ‘Sensation’ denotes a judgment in the mind.

S4: ‘Sensation’ denotes a sensible .13

When it comes to Descartes’ use of ‘sensation’, then, one cannot help but to handle it on a case-by-case basis as well. Nonetheless, a sense of the term roughly aligning with Smith’s fourth definition (S4) is prominent within my reading, and it helps to be forthright on this terminological matter. However, my intended meaning relies on yet another distinction in

Descartes’ conceptual machinery, and so I introduce this distinction first.

13 Smith 2005, 565 - 569. Smith’s fifth definition (S5) is: “ ‘Sensation’ denotes a corporeal-mental modal complex.” This is the definition that has the most similarity to my overall reading, although, for purposes of lexical bookkeeping, I will not take up his precise terminology. 12

Descartes distinguishes between two types of qualities, qualities that are nowadays labeled as primary qualities and secondary qualities.14 In referencing this distinction, I appeal to sensible qualities or phenomenal characteristics (unless explicitly noted otherwise). Thus I mean to employ the distinction in relation to perceived secondary qualities and perceived primary qualities. For Descartes, what marks one type of quality off from the other is whether or not the given quality can resemble something in the physical world. Thus, in the Principles Descartes splits the two apart as follows:

It is clear, then, that when we say that we perceive colours in objects, this is really just the same as saying that we perceive something in the objects whose nature we do not know, but which produces in us a certain very clear and vivid sensation which we call the sensation of colour...Of course, we do not really know what it is that we are calling a colour; and we cannot find any intelligible resemblance between the colour which we suppose to be in objects and that which we experience in our sensation. But this is something we do not take account of; and, what is more, there are many other features, such as size, shape and which we clearly perceive to be actually or at least possibly present in objects in a way exactly corresponding to our sensory perception or understanding (AT VIIIA 34 / CSM 1 218).

For all we know, the physical world is colorless, and so phenomenal color is nothing more than the effects of the physical world on one’s mind. Perceived color is thus a perceived secondary quality. Perceived shape, on the other hand, can resemble things in the world of physical bodies. The physical world is extended, and so can be circular, rectangular, and so on, and can thereby resemble things in sensory experience. Perceived shape is thus a perceived primary quality. And the primary-secondary quality distinction is not the only point of interest in this passage.

Notice that Descartes appears to use ‘sensation’ in a way synonymous with ‘sensory perception’, that is, he seems only interested in using ‘sensation’ as a way of talking about phenomenal characteristics. ‘Sensation’ in this passage has little relevance to the

14 Descartes did not invent these terms (that honor belongs to Robert Boyle). However, it is part of the common tongue now, so I use it here. 13 presentation thesis, since Descartes seeks to draw a distinction within the category of phenomenal characteristics itself (thus leaving intentionality aside). But in contrast, consider a passage appearing not much later in the Principles, in which Descartes discusses a pre-theoretical view of sensory experience,

And when nothing very beneficial or harmful was happening to the body, the mind had various sensations corresponding to the different areas where, and ways in which, the body was being stimulated, namely what we call the sensations of tastes, smells, sounds, heat, cold, light, colours and so on—sensations which do not represent anything located outside our thought. At the same time the mind perceived sizes, shapes, and so on, which were presented to it not as sensations but as things, or modes of things, existing (or at least capable of existing) outside thought, although it was not yet aware of the difference between things and sensations (AT VIIIA 35 / CSM 1 218 – 219).

In this passage Descartes seems to abide by a stricter notion of ‘sensation’, one which extends only over “tastes, smells, sounds, heat, cold, light, colours and so on.” That is, he seems to understand ‘sensation’ here as referring exclusively to perceived secondary qualities. This sense of ‘sensation’ is not only evidenced by the qualities he lists off, but also by his explicit demarcation between ‘sensations’ and “things, or modes of thing, existing (or at least capable of existing) outside thought,” a demarcation suggesting that perceived primary qualities are not sensations strictly understood. This later use of

‘sensation’ is important for my purposes. For at critical junctures of my overall reading, it is of consequence whether Descartes’ means sensation in this specific restricted way or sensory perception broadly considered. Thus, I take care to note which sense of the term is relevant when needed.

Now that I cleared up terminological concerns and provided reasons for why a rather localized question about ontology and intentionality has global—and debatable— ramifications for Descartes’ philosophy, let’s next turn to the specifics of how I hope to

14 defend the presentation thesis and thereby undercut more conventional renderings of

Descartes’ dualism.

Contrary to what one might expect, Chapter 1 focuses neither on intentionality nor on the brain. Rather, I begin with Descartes’ mechanical theory of light deflection, giving most attention to the process by which retinas come to have “perfect” resemblances imprinted on them.15 Readers will come to see that this is a part of Descartes’ theorizing that ought not to be overlooked, for the mechanical processes that Descartes posits in his theory of light deflection are pivotal to understanding how minds come to be informed about the surrounding world, especially when it comes to understanding how perceived primary qualities can resemblance their objects. As an additional lesson of the chapter, I show that Descartes’ mechanical theory of light deflection is, in some important ways, a mechanization of his Scholastic predecessors, despite his sharp tongued criticisms lodged against them. The texts I primarily engage are the Optics and Treatise on Light, two of

Descartes’ earliest works that nonetheless give a comprehensive account of his of visual perception. In my of these texts, I develop the notion of what I call

“directional configurations,” purely mechanical entities causally linking minds with the external world. As is shown in subsequent chapters, directional configurations are ultimately responsible for creating images on the pineal gland’s surface.

Chapter 2 is the dissertation’s fulcrum in three ways. In its earlier sections, I survey numerous passages in order to show that Descartes’ avowals of the presentation thesis have a frequency and longevity that recommend its serious consideration. I then

15 I use the term ‘mechanism’ and its cognates as referencing a natural philosophy attempting to explain all macroscopic physical phenomena in terms of impact between and motion of tiny, microscopic particles characterized only in terms of size, shape, and motion. I borrow this rendering from Downing 1998, 381 fn 2. 15 move to argue that once it is realized how closely the notion of directional configurations fits with Descartes’ views on brain physiology, the presentation thesis turns out to be much less inscrutable than commentators commonly believe. In the final sections, I develop and defend the notion of impressional causation, a specific type of efficient causation especially relevant to visual shape perception. I argue that impressional causation, at least in body-to-mind causal interaction, commits Descartes to a special numerically identical mode shared between body and mind, and that, in the end, the presentation thesis is impressional causation conceived from the mind’s side of things, as it were. The texts I examine span the entirety of Descartes’ philosophical career, involving works as early as the Rules for the Direction of Mind and ones as late as the Passions of the

Soul.

The combined results of Chapters 1 and 2, I hope, quiet a number of complaints lodged against the presentation thesis. Even so, Descartes’ Optics presents a tricky passage for the thesis, especially for anyone believing that it is his considered view. But, as

I argue in the early sections of Chapter 3, when the oft cited “eyes in our brain” passage is considered in light of the Optics’ detailed mechanics of vision, interpreters are in no way obligated to take it as a strong objection to the thesis. The later sections of Chapter 3 apply the Optics’ mechanical account of vision to Descartes’ comments in the Sixth

Replies, where he introduces the three grades of sensation. By bringing these two texts together, I develop a plausible construal on behalf of Descartes about how two- dimensional images on the pineal gland come to be perceived as three-dimensional.

Chapter 4 branches out into the presentation thesis’ legacy by discussing its influence on Nicolas Malebranche, a Cartesian of notable reputation during the early 16 modern period. I start with a brief examination of Malebranche’s (in-)famous vision in

God , and discuss how, at least at a general level, the vision in God shares important structural features with the presentation thesis. The chapter’s midsection explores possible reasons that Malebranche may have had for denying the letter but keeping the of Descartes' thesis. In the final section, I conclude that although

Malebranche’s views on causation bars the brain from the mind, Malebranche’s need to give a convincing account about the epistemic reliability of resembling causes motivates his endorsement of the presentation thesis’ structure.

17

Chapter 1: Illumination

Descartes’ Optics was published in 1637 as an appendage to his Discourse on the

Method. Despite being a relatively youthful work, Descartes treated it as a canonical text on his mechanical hypotheses, often referring to it in his mature works. In this chapter I give attention to the Fifth Discourse of the Optics, where Descartes presents the mechanics of retinal image formation. I argue that there is a particular inadequacy in the proffered mechanical hypotheses of the Fifth Discourse, an inadequacy made transparent by placing Descartes’ theory of visual sensory perception in light of his Scholastic predecessors. I conclude by developing a thoroughly Cartesian response to the inadequacy and, as a consequence, show that, in some important ways, Descartes mechanized the Scholastic theory of visual sensory perception.

Section 1

The title of the Fifth Discourse is “Of the Images that form on the Back of the

Eye,” and being such, is meant to provide a mechanical characterization of how miniature, two-dimensional retinal images are formed. The cornerstone of Descartes’ theorizing on this topic is the notion that human eyes are nature’s own camera obscura. He writes in the Fifth Discourse,

Some people have very ingeniously explained this already, by comparison with the images that appear in a chamber, when having it completely closed except for a single hole, and having put forth in front of this hole a 18 glass in the form of a lens, we stretch behind it, at a specific distance, a white cloth on which the light that comes from the objects outside forms these images (AT VI 114 / CSM 1 166 / O 91).16

Although the camera obscura (“darkened room”) is an ancient invention, it was the medieval Arab scholar Alhazen who coined the term and helped cement its relevance to the study of optics. In Figure 2 below, we see the typical setup of a medieval camera obscura.17

Figure 2. Alhazen's Camera Obscura

According to Descartes, the image formed on the “white cloth” in setups like the one above is like the image formed on retinal surfaces. As we can gather from Figure 2, the

16 As the quote suggest, Descartes was not the first to compare the eye to a camera obscura. He is likely referring to the works of Giovanni Battista Della Porta and Johannes Kepler, who both helped popularize the idea within the early modern era. See Lindberg 1976, 184 and 205 – 206 for Della Porta’s and Kepler’s use of the camera obscura, respectively. 17 Image taken from Zewail 2010, 1193. 19 image formed on the cloth resembles things outside the camera obscura, and, thus, by analogy, images formed on retinal surfaces resemble their objects. Like the projection of the towers on the white cloth in Figure 2, each retina has a miniaturized, inverted, and two-dimensional geometrical resemblance imprinted on it. This resemblance differs only in size, and so the projection on the cloth and impressions on the retinas are geometrically similar to their objects. This construal of ‘resemblance’—that of geometric similarity—is the one that I use here and throughout (unless specified otherwise).

But in likening the human eye to a camera obscura, Descartes was doing more than offering an argument by analogy. He was also appealing to anatomical discoveries of the period. In the Fifth Discourse he invites readers, for example, to examine the “eye of a newly deceased man, or, for want of that, of an ox or some other large animal” in order to confirm that “you will see there, not perhaps without admiration and pleasure, a picture which will represent in natural perspective all the objects which will be outside it” (AT VI

116 – 117 / CSM 1 166 – 167 / O 91 – 93).18 Anatomical thus corroborates

Descartes’ analogical reasoning, thereby giving him license to apply the geometrical theory derived from the camera obscura to the human eye. Thus, having paid his evidential dues, Descartes next turns his attention in the Fifth Discourse to such geometrical findings, the purpose of which is to trace out the path that deflected light travels on its journey from an object to the eye.

18 The experiment is somewhat more complicated than the above quote suggest. It in fact requires that the inner membranes of the eye be sliced open so as to reveal the inmost humor, next covering the humor with a thin paper or eggshell, and then exposing it to natural light. See AT VI 115 / CSM 1 166 / O 91 – 93. 20

Descartes explains the geometry of light transmission by appealing to this diagram:19

Figure 3. Light Transmission

The route of light is determined by the manner in which tiny particles collide with large and sufficiently solid bodies. The diagram above is meant to show the of light

19 This image is from Aribini’s 1983, but it is a clearer version than the one included in the Optics itself, and so I borrow it. See Arbini 1983, 324. 21 after it impacts such a body and thereby orients toward the eyes.20 But in order for deflection to occur in the first place, light must originate from luminous bodies, such luminous bodies being objects 11 and 12 in Figure 3. Thus, what the diagram shows is that objects V, X, Y deflect light from luminous bodies (11, 12), in turn causing light to move in directions toward R, S, T, respectively (located at the bottom of the image). Thus, to bring attention back to the notion of resemblance, the image spanning R, S, T thereby resembles

V, X, Y in a way that is “as perfect as possible.”21

There is a certain inadequacy here, however. For although Descartes provides readers with an astute map, it is nonetheless simply a map. Descartes gives a description of the roads traveled, yet says nothing about the vehicle or precautions one should take to safely arrive. But why does the vehicle and even the precautions matter? Is the route not enough to know?

The reason there is a sense of dissatisfaction with the way things stand so far in the

Fifth Discourse is a matter related to the mechanical origins of retinal images. Descartes holds that retinal images directly result from bodily impact, but in its current state,

Descartes’ view of light transmission offers no reassurance that light can be transmitted in such a way that conveys resemblance merely by way of bodily collision. To help sharpen the problem, consider Descartes’ description from Rule 12 of his Rules for the Direction of the Mind,

20 Descartes’ account here is historically significant because he implicitly endorses Kepler’s revolutionary visual theory, which was published just thirty years prior to the Optics. Before Kepler’s 1604 publication Ad Vitellionem Paralipomena, it was commonly thought that only light rays landing perpendicular to the external eye (B, C, D in the diagram) are transferred into the internal eye. But as the diagram makes clear, light rays landing obliquely to the external eye are transferred into the internal eye as well, thus resolving longstanding difficulties in regards to oblique rays. See Lindberg 1976, 193 – 202. 21 As the diagram suggests, the retinal image formed by R,S,T (and additional points) is a reversed image of the object. This is a point that both Kepler and Descartes note. Kepler did not endeavor to explain how the mind corrects this reversal, while Descartes attempts to explain it by appealing to actions of the soul. For a discussion of Kepler’s on the matter see Lindberg 1976, 202 – 205. For Descartes comments see AT VI 121 – 128 / O 96 – 99 (the relevant portion is abridged from CSM). For Descartes indebtedness to Kepler’s work see Sabra 1981, 12. 22

...sense-perception occurs in the same way in which wax takes on an impression from a seal. It should not be thought that I have a mere analogy in mind here: we must think of the external shape of the sentient body as being really changed by the object in exactly the same way as the shape of the surface of the wax is altered by the seal....thus, in the eye, the first opaque membrane receives the shape impressed upon it by multi-coloured light; and in the ears, the nose and the tongue, the first membrane which is impervious to the passage of the object thus takes on a new shape from the sound, the smell and the flavour respectively (AT X 412 / CSM 1 40; emphases mine).

The ring and wax example is no mere analogy. Rather, it is a mundane example of a type of (efficient) causal relation holding between physical objects, a type in which colliding particles impress images into surfaces. I call this type of causal relation “impressional causation” and characterize it as follows:

(1) the affected thing and the affecting thing are bodily surfaces,

(2) both the cause and effect are geometrical configurations,

(3) the cause and effect resemble one another, and

(4) the relevant causal mechanism is contact (of sufficient motion) between bodily surfaces.22

I will be concerned more deeply with impressional causation once I turn to Descartes’ thoughts on the brain. The importance of the notion now, though, is the demand that it makes on Descartes’ theory of light transmission. Taking (2) into account, one gathers that mere motion is not sufficient to explain how retinal images are produced. They are caused by something with geometrical properties as well—just as the image in the wax is caused by the shape of the ring. Moreover, as (3) suggests, resemblance is also transferred through the air, so such a cause has to be capable of transporting geometrical similarity through a medium, or at least something capable of reproducing it upon impact. Thus, for a complete account, Descartes needs to inform readers about the method of delivery, and not just about the paths travelled.

22 As it stands presently, treating particles as a “surface” is left undefended. However, this topic receives much closer attention in what follows. 23

However, the remainder of the Fifth Discourse has little to say on the matter.

After completing his description of the diagram in Figure 3, Descartes immediately moves to explaining the physical causes of perceived color, but perceived color falls among non- resembling qualities, and therefore has little relevance to the issue.23 And when Descartes then declares that he is going to explain how the “three points R,S,T…keeping between them the same order as objects V,X,Y, manifestly do resemble them” (AT VI 119 – 120 / O

94), he seems more interested in discussing the eye’s ability to refract light, which, although an important feature of visual physiology, does not directly address the concern either.24 Thus ends what the Fifth Discourse says about “perfect” retinal images.

I believe Descartes does have something more to say on the matter, though, and that it can be extracted from earlier sections of the Optics. However, Descartes’ Scholastic heritage helps frame his commitments on the issue, and so it is worth discussing a few things about late Scholastic views on visual sensory perception first.

Section 2

It is far beyond the present scope to collect the many of late Scholastic philosophers on visual sensory perception. Fortunately, Alison Simmons’ work on the relationship between late Scholastic theories of visual perception and Descartes’ own can

23 In short, the physical cause of color sensation for Descartes is this: the ratio between the rotation of light ray particles and the forward motion affects an object’s surface in such a way that uniquely determines color sensations. Certain bodies appear black because they absorb the spin or “” of light particles, whereas white bodies deflect particles without any loss or gain to circular motion. 24 The relevant portion is abridged from CSM. 24 be relied on here.25 In what follows, I summarize key points of Simmons’ interpretation of

Antonio Rubio, Francisco Suarez, and Francisco Toledo on visual perception, hoping to show in the next section how Descartes is influenced by them.26

At the heart of these three Scholastics’ theory of visual perception is the

Aristotelian claim that perceivers assimilate to what they perceive. Traditionally, this is understood as involving an alteration in the patient (the perceiver) caused by the agent

(the perceived object) and that, moreover, the alteration moves the patient from a state of dissimilarity to a state of similarity. As Rubio states it, “in the beginning [of sensory perception], the patient is dissimilar to the agent, but in the end it is similar”

(Commentary II.v ex., 305).27 So, for example, in the case of sensing heat, the warmth of a full coffee mug causes one’s own hand to move from coolness to warmth (or, perhaps, versa if the mug is empty). And these three Scholastics believe that visual perception is no different, for it too requires assimilation.28

Simmons identifies a second requirement derived from the basic Aristotelian framework: any alteration requires contact between agent and patient. In Aristotle’s words this time,

Nor again is there anything intermediate between that which undergoes and that which causes alteration: this can be shown by induction; for in every case we find that the respective extremities of that which causes and that which undergoes alteration are together ( VII.2, 244b 3 – 5).29

25 I use Simmons 1994A as the main source for the following discussion. However, Simmons 1994A is but a summary of points in her 1994B dissertation. Thus, when relevant, I cite Simmons 1994B. 26 As Simmons notes, Descartes would have been familiar with the work of Rubio and Toledo by way of his training at La Flèche, whereas Descartes specifically refers to Suarez in the Fourth Replies. See Simmons 1994B, 49 – 50, fn 9. 27 Translated by and quoted in Simmons 1994A, 262. See also Simmons 1994B, 74 – 75. 28 This does not imply for the three Scholastics, however, that the eye literally becomes, say, blue during one’s phenomenal experience of blue. The precise manner in which visual perception is an assimilation of the perceived object will be discussed once I turn to the Scholastic notion of intentional . 29 Translated by Jonathon Barnes and quoted in Simmons 1994A, 261. 25

But since there is no direct contact between the perceiver and perceived in the process of vision, Aristotle and the three Scholastics posit a medium between the patient and agent of visual perception, a medium making direct contact with both the perceiver’s eyes and the perceived object. As these Scholastics claimed, since the medium is responsible for assimilating the perceiver to the perceived, the medium too assimilates to the perceived object. 30

The three Scholastics identified air as the requisite medium. However, by their , merely saying that air assimilates to the perceived object is not sufficient, for an intermediary natural agent is required to actualize the assimilation. The intermediary agent was coined an “intentional species,” and is thought to be something emanating from the perceived object that, in turn, acts upon both the air and the patient, ultimately assimilating the patient to the agent. In terms of ontological classification, intentional species are conceived of as material accidents belonging of the medium itself, albeit material in a unique way.31

Objects such as rocks, plants, and human bodies are complete material , whereas intentional species are less complete.32 As Suarez writes,

…intentional species are not more perfect than their objects, but rather they are like vestiges of them and even more tenuous entities. White, for example, is a perfect entity in its own order; but truly, the species of white are not equal to them in that order (Commentary III.ix.4, 648).33

30 See Simmons 1994B, 73 – 76 for a fuller explanation. 31 The underlying reason for attributing a material nature to intentional species is twofold: (a) material mediums only actualize accidents proportionate to their mode of being and (b) intentional species, in of being produced by a material object, must also be material. See Simmons 1994A, 264. 32 For Aristotle, the ontological item corresponding to the Scholastics’ intentional species is simply “form without matter.” This phrasing spurred a mild controversy among Scholastic commentators, however, insofar as some like Aquinas understood Aristotle to posit “spiritual” intermediaries whereas our three late Scholastics understood him as positing “less complete” matter. For Aquinas’ view see Aquinas 1926, 433 – 434. For Aquinas’ view in relation to Descartes’, see Crifasi 2011, 143 – 144. 33 Translated by and quoted in Simmons 1994A, 264. 26

As less complete grades of material being, intentional species do not sensibly alter the perceptible qualities of the medium—the air does not appear blue simply because it is altered by the intentional species of blue. In Rubio’s words, “since they [intentional species] do not have natural being but a diminished being, they cannot produce natural effects, nor can they be sensed or seen” (Commentary II.viii.2, 410).34 In short, intentional species are imperceptible material accidents.

At a general level, then, Descartes does not deviate from the late Scholastics on at least two counts. First, Descartes appears to operate under an assimilation constraint of sorts. He is committed to claiming that some sensory organs indeed assimilate to their objects, for, as we saw, retinas resemble their objects. There is also a contact constraint at work in Descartes’ theorizing, for, as we also saw, retinal images are the result of impressional causation. Thus, for Descartes, the production of retinal images requires assimilation to and contact with something external to the eye. Nonetheless, there appears at first blush an important difference between what we have seen of Descartes’ theory and what we have seen of his Scholastic counterparts. The latter group provides a story about the method of delivery—they put a vehicle on route and give some reason to expect a safe delivery. Descartes, though, gives no such explanation so far. However, as I noted earlier, I think the Optics provides resources to manufacture what Descartes’ theory lacks, and, consequently, that Descartes adheres to the scheme of his predecessors more closely than initial appearances let on. For I argue in the next section that, like the late

Scholastics, Descartes holds that the medium itself assimilates to the perceived object.

34 Translated by and quoted. in Simmons 1994A, 265. 27

Section 3

In the Treatise on Light, Descartes argues that the material world is a plenum, a world saturated by physical bodies. The bodies populating the plenum divide into three or “elements”: fire, air, and earth. This categorization roughly maps onto the production, transmission, and deflection of light, respectively. 35 The smallest bodies belong to the category of fire, and are extremely active in comparison to the other types, moving as they do throughout the plenum in a fluid-like manner. The category of air includes bodies that are larger and slower than fire particles. These bodies impede (but just slightly) fire particles traveling through the plenum because they loosely bunch together, thereby functioning as barriers to their tinier, more excited counterparts. But, as one might surmise, bundles of air particles are imperfect barriers, and are made so by numerous gaps in the bundles. Thus, “it is much easier for the first element [fire particles] to slide into these [gaps] than for the parts of the second [air particles] to change shape expressly in order to fill them” (AT XI 24 / G 17).36 The role of air particles in light transmission, then, is twofold: they are at once the impediment to and tunnels by which fire particles move.37 Last up are the largest and slowest particles: earth particles. Like air particles, earth particles tend to bunch together. Unlike air particles, however, the bundles of earth particles succeed as barriers. For the bundles of earth particles are so tightly collected that fire particles cannot make their way through, thus deflecting and redirecting fire particles elsewhere.

35 This comparison is Stephen Gaukroger’s. See G xvi. 36 The relevant portion of the text is abridged from CSM. 37 Per the plenum , this does not mean that the gaps are empty. Rather, we must imagine that these gaps are continually filled by fire particles. 28

Descartes summarizes the view as follows:

For the form that I have attributed to the first element consists in its parts moving with such a great speed and being so tiny that there are no other bodies able to stop them; in , they need have no determinate size, shape, or position. The form of the second element consists in its parts having such a middling motion and size that, just as there are many causes in the world which could increase their motion and diminish their size, there are as many that could do the opposite; and so they always remain balanced as it were in the same middling condition. And the form of the third element consists in its parts being so large or so closely joined together that they always have the force to resist the motions of other bodies (AT XI 26 – 27 / CSM 1 26 – 27 / G 18).

Although Descartes does not employ the elemental vocabulary in the Optics, it nonetheless enriches his comments in the work. For each element’s role in light propagation mirrors three important analogies from the First Discourse. These analogies—like the three elements—explain the production, transmission, and deflection of light. In the third analogy, I argue, one finds intentional species and an assimilation requirement in disguise. But to make most sense of the third, I start with the first.

In the first analogy, Descartes draws readers’ attention to the example of a blind man using guiding sticks to surmise his whereabouts. Descartes wants readers to notice that that the blind man determines his surroundings by way of motion alone communicated through the stick. The analogy’s takeaway for Descartes is thus: “I would have you consider light as nothing else, in bodies that we call luminous, than a certain movement or action, very rapid and lively, which passes toward our eyes through the medium of the air and other transparent bodies” (AT VI 84 / CSM 1 153 / O 67). In other words, light is nothing but motion—a mode of body transferred almost instantaneously through a medium. Put in context of the three elements, the analogy suggests that fire particles and small air particles function within the plenum as a type of network “passing”

29 rapid motion from one to another.38 Thus, the production of light is the production of motion, a motion transferred through contiguous particles.

The second analogy expands on the first. In it, Descartes asks that readers bring to mind wooden grape pressing tubs, and, in addition, prompts readers to imagine that grape juice flows through two holes located at the tubs’ bottom. Descartes wants readers to observe that, when the grapes are pressed, juice moves toward either of the holes in the manner of a straight line, even if the juice curves around imposing grapes. In other words, the juice tends toward linear motion with respect to the holes, although the actual path the juice follows may not trace out a straight line. Thus, contrasting the actual haphazard course or “movement” with the more abstract “action” of linear tendency, Descartes writes, “And in the same way considering that it is not so much the movement as the action of luminous bodies that must be taken for their light, you must judge that the rays of this light are nothing but the lines along which this action tends” (AT VI 88 / CSM 1 155

/ O 70). Translating his point into the vocabulary of elements, the analogy teaches that, although the motion of light actually moves non-linearly through, say, bundled air particles, the motion nonetheless moves in an overall linear tendency. Thus, an additional feature of light’s ontology emerges: light is a linearly tending rapid motion of particles.39

And so, for ease of explanation, I henceforth use “light particle” to reference particles moving with this tendency.

Finally, in the third analogy Descartes compares deflected light particles to macroscopic deflection. He claims that when light particles “meet certain other bodies

38 Throughout the Treatise on Light, Descartes treats both fire and air particles as responsible for conveying movement through the plenum. 39 Descartes concludes the second analogy by stating that one should conceive of an infinite number of light rays as emitting from luminous bodies in all directions. This point, although an important detail, does not conflict with any points I make. 30 they are liable to be deflected by them, or weakened, in the same way as the movement of a ball or of a rock thrown in the air is deflected by those bodies it encounters” (AT VI 88 –

89 / CSM 1 155 / O 70). He elaborates by appealing to a diagram,

Figure 4. Light Deflection

Thus, when many balls coming from the same direction meet a body whose surface is completely smooth and even, they are deflected uniformly, and in the same order, in such a way that if this surface is completely flat, they keep the same distance between them after having met it as they had beforehand; and if it is curved inward or outward, they approach or depart in the same order from each other, more or less, because of this curvature. You can see here that the balls A, B, C, after having met the surfaces of bodies D, E, F, are deflected toward G, H, I. And if these balls meet an uneven surface, such as L or M, they are deflected in different directions, each according to the position of the part of the surface it touches. And they change nothing but this in the manner of their movement, when the surface’s unevenness consists only in the fact that its parts are differently curved (AT VI 90 / CSM 1 156 / O 71).

As Figure 4 shows, light particles colliding with a smooth surface, D, deflect at identical angles of incidence, causing movement in parallel directions. But for convex, concave, or irregular surfaces (surfaces E, F, M, L, respectively) varying angles of incidence cause light particles to scatter in uniquely non-parallel directions. The general lesson is that deflected light particles form unique scattering and that, moreover, the shape of the deflecting surface determines scattering pattern. In other words, there is a one-to-one

31 correspondence between surface structures (made out of earth particles) and resulting scattering patterns (of light particles).

The First Discourse thus informs readers more about the specific ontology of light and, additionally, teaches that shapes of deflecting surfaces uniquely determines scattering pattern. So, then, where is the Cartesian intentional species and assimilation requirement in this?

Let’s begin by considering a Cartesian inspired illustration. The left side of Figure

5 depicts five tennis balls prior to being deflected by a sphere, whereas the right side depicts the tennis balls after deflection:

Figure 5. Directional Configurations

32

Figure 5 thus depicts tennis balls moving linearly toward a sphere and moving linearly away. The contrast I want readers to notice is that the tennis balls trace out different shapes in each side of the illustration: the tennis balls on the left trace out a straight line while those on the right trace out a curve. These “traced out shapes” are second-level geometrical properties—they are the property of structure.40 I propose that such structures are the items missing from the geometrical description in the Fifth Discourse, and I call these items “directional configurations.” Putting together the notion of directional configurations takes a bit of care, however, since I derive it principally from the three analogies, the first two of which stand in a problematic relation with the third. In particular, the third analogy—the tennis ball analogy—treats light as if it is a particle itself—not just the motion of particles. If the notion of directional configurations is to be of service, then it must smooth out this apparent tension.41

Putting the problem in a slightly different manner, the commitments that emerge from the analogies, and the ones that present a possible problem, are that (a) structure is a second-level property of particular groupings of particles and that (b) light transmission does not reduce to any one grouping of particles. The former, I take it, is a lesson of the third analogy and the second a lesson of the first two. But these dual commitments need conflict only if it is additionally supposed that structure is not transferable from one group

40 This higher-level geometrical structure is how I interpret Descartes’ comment in the Fifth Discourse about particles “keeping the same order” after deflection. In addition, John Sutton argues that, for Descartes’ brain physiology, these sorts of patterns are responsible for producing pineal images. Regarding Descartes, Sutton writes, “This key of the ‘pattern’ is essential for the neurophilosophy to get off the ground. ‘Pattern’ and the related term ‘disposition’ are something like second-order physical properties, properties which supervene on first-order physical properties like size, shape, rotation, and so on” (Sutton 1997, 89). In the next chapter, I expand the notion of directional configuration so as to include brain physiology, and so agree with Sutton. Relatedly, one can thereby take my introduction of directional configurations as providing the requisite groundwork for moving these patterns from without the body to within it. Finally, Sutton discusses some objections to these patterns (deriving mostly from issues in ) that some readers might find enlightening. See Sutton 1997, 89 – 90 for his responses to these objections. 41 I owe this observation of an apparent tension to Wolf-Devine, although she does not read Descartes as avoiding it. See Wolf-Devine 1993, 41. 33 of particles to another. This assumption, however, does not appear to be expressed by

Descartes, either implicitly or explicitly. Indeed, the contrary seems necessary if one hopes to charitably interpret Descartes’ theory of light transmission. Let’s summarize and slightly re-conceptualize Descartes’ theory to see why.

Light has to be capable of impacting a surface, and doing so in way that impresses shape. Being a mode of particles, light is capable of doing this, at least in . But, in contrast, light is not transmitted in virtue of belonging to an isolated group of particles.

Transference of motion requires a network of particles, each particle acting as a sort of

(extremely) temporary resting place for the motion of light. Light, then, is like the movement of waves in the ocean. The motion of a distant wave belongs to an entirely different set of water droplets than the motion eventually ending up at the shore, but, nonetheless, the water collectively manages to transfer a generally curved shape. The idea that Descartes seems to view the motion of light as akin the motion of waves helps one get a better grip on what Descartes ultimately appears committed to in his theory of light and, in turn, provides a stable footing for the notion of directional configurations.

The below image is taken from J.B. Zirker’s The Science of Ocean Waves, and depicts what happens underneath the ocean’s surface during wave propagation:

34

Figure 6. Wave Propagation

Zirker describes the picture’s import as follows,

Under the surface, a traveling water wave looks like the inside of a fine clock, filled with carefully synchronized “gears.” The gears are actually the vertical circular of small blobs of water (let’s just say the size of a blob is a small fraction of the wavelength). The orbits decrease in size the deeper one looks. Moreover, except for a very small drift in the forward direction, each remains in its place as the crest passes by (Zirker 2013, 16).

Zirker’s image and description help visualize what Descartes has in mind. Light, at least as Descartes understands it, is just like the sinuous line running throughout the top of each column: it is a motion transferred throughout a series of otherwise stationary particle groupings. Thus, to bring this lesson from ocean studies into contact with the analogies,

Descartes overall appears to claim that such groupings (like those in the lettered and numbered columns of Figure 6) take on the shape of a deflecting object’s surface and then transfer that shape outward into the plenum. However, the third analogy problematically 35 treats the particle grouping immediately contacting the deflecting object’s surface (what one can imagine as column A) as the only relevant bunch, a view that does not instantly cohere with Descartes’ official ontology of light. The trick to fixing this problem, however, is to realize that the batch of particles touching the deflecting surface is not the only relevant group, but rather that an entire network of groupings is required.

The group of particles immediately contacting the deflecting object’s surface forms a collective surface, a collective surface having the shape of the deflecting object’s surface impressed into it. This first grouping of particles, in turn, impresses the shape into the immediately adjacent group, and so on until the shape impresses upon retinas. The below image aims to provide a rough visualization of the process:

Figure 7. Shape Transmission

36

Fire particles—and, in turn, air particles—thus function as a series of de facto surfaces that instantaneously (or near to it) collide with one another in such a way that retains the shape of a deflecting body, a body like the earth particles in Figure 7. Therefore, although particular sets of particles do in fact take on the shape of an object’s surface, it is not any one group that single handedly transfers shape through the plenum. A series or network of particles is required, and each component (de facto surfaces) of the series interacts with one another merely by way of collision. As I read him, then, Descartes creates waves by impact.

The notion of directional configurations can now be spelled out more precisely. It is the geometrical structure impressed, near instantly, in a series of de facto surfaces, surfaces that consist of grouped particles.42 So, as a second-level property, directional configurations ought not to be classified as light strictly conceived. Light is directed motion, and nothing more. Directional configurations, on the other hand, are emergent properties attributable to particles bumping into one another in a way that, at least functionally, amounts to a network of interacting surfaces, surfaces that have one shape or another impressed into them.43 Let’s be clear, though, about what the notion of directional configurations does and does not do for Descartes’ theory of visual sensory perception.

First, it provides a way of reconciling some of Descartes’ seemingly disparate commitments. It unifies the idea that retinal images result from collision with the first

42 Gary Hatfield and William Epstein hint at such an entity, but do not attempt to discuss how it explains the strong resemblance between the retinal image and its object. See Hatfield and Epstein 1974, 374 – 375. 43 What is the dimensionality of directional configurations? Simply due to the fact that they are made up out of tiny bits of matter, they are obviously grounded in three dimensional properties. These bits of matter have width, depth, and breadth. However, since directional configurations are second-level properties, they do not have a dimensionality all of their own. Thus, in this second sense, they lack dimensionality. 37 and second analogies’ claim that motion is just rapid, linearly tending motion. Moreover, it gives consistency to the three analogies: shape is transmitted through the plenum (at near instantaneous speeds) although light is nothing more than the motion of particles.

Second, it interestingly links Descartes with his Scholastic predecessors—it is where one finds the disguised intentional species and the assimilation of a medium.

According to the late Scholastics examined earlier, the medium itself assimilates to the perceived object by taking on an intentional species (as an to the medium). The notion of directional configurations commits Descartes to the same vein of thought because, simply, groups of particles assimilate the shape of deflecting surfaces. One difference, of course, is that the Scholastics claimed that just air takes on properties of the perceived object, rather than, in addition, bunches of little fire particles slipping through air itself. But this is a minor detail that one can pass over with relative ease. However, what ought not to be passed over with such casualness is the relation between directional configurations and intentional species. For Descartes views intentional species as a philosophical blunder, but if one is not careful, directional configurations might seem uncomfortably familiar.

Such discomfort originates from Descartes officially barring “little images” from his theory of light transmission, making a quip early on in the Optics about “those little images flitting through the air, called 'intentional forms', which so exercise the imagination of the philosophers” (AT VI 85 / CSM 1 153 – 154 / O 68). Some prominent scholars read this passage and those like it as a straight denial of any and all imagistic entities moving about the plenum. Lilli Alanen, for example, claims that Descartes denies any “mechanical transmission of images or likenesses” (Alanen 2003, 133 en 27), and John 38

Yolton reads the Optics as asserting that visual processes “do not require any entities

(particles or images) to be transmitted from object to perceiver” (Yolton 1984, 29).44 I argue to the contrary, however, so some reconciliation is required on behalf of my reading.

Although I believe that Descartes commits to something like intentional species insofar as he posits imagistic assimilations moving about the plenum, I do not think my reading commits him to what he conceives of as the problematic features of intentional species. As I understand the matter, Descartes’ dissatisfaction with intentional species is born out of the need for a geometrically centered ontology. The general aim of the

Scholastics is to extend and defend Aristotle’s metaphysics, which committed them to explaining visual perception in terms of form, matter, accident, and so on. Descartes, on the other hand, adopted the teachings of an optical spanning from Alhazen, through , and culminating in Kepler, a tradition explicating the transmission of light in purely geometrical terms.45 Descartes incorporated this general attitude into his own theorizing by positing ontological items fully explicable in the of geometry, at least in principle. Thus, Descartes’ gripe with intentional species is a matter of ontology, not a matter of imagistic resemblance. He denounces intentional species because they are, in principle, geometrically inexplicable, the chief problem being their

44 Insofar as she explicitly agrees with Yolton, Wilson endorses this reading as well. See Wilson 1990, 18. 45 Alhazen (c. 965 – c. 1040) revolutionized optical theory by arguing that only light rays landing perpendicular to the eye inform visual perception, by comparing light rays to moving projectiles, and by introducing the “visual pyramid” (among other things). And although Alhazen discussed his theory in terms of “forms of light” entering the eye, these “forms” are not clear analogues of “forms” in Aristotle’s sense. See Lindberg 1976, 71 – 86. Roger Bacon (c. 1214 – 1292) adopted Alhazen’s geometry of vision, but attempted to synthesize it with Aristotelian visual theory. In particular, he states “But a species is not a body, nor is it moved as a whole from one place to another; but that which is produced [by an object] in the first part of the air is not separated from that part…rather, it produces a likeness to itself in the second part of the air, and so on” (qtd. in Lindberg 1976, 112). In this passage Bacon redefines intentional species to fit with Alhazen’s optical theory, but nonetheless posits an ontological difference between light rays and species. See Lindberg 1976, 107 – 116. Johannes Kepler (1571 – 1630) continued with the geometrical tradition, but argued against Alhazen by claiming that even light rays landing oblique to the eye inform visual perception, and a key feature his theory is that a reversed image of an object is impressed upon the retina. Kepler, however, was not interested in synthesizing Aristotelian metaphysics with his optical theory. See Lindberg 1976, 193 – 205. As noted above, Descartes’s Optics endorses Kepler’s optical theory. Finally, as Hatfield and Epstein note, Descartes did not differ from the tradition of Alhazen in terms of optical theory, but rather did so “in the ontology of physiological processes.” See Hatfield and Epstein 1979, 374. 39 status as less complete material accidents. But directional configurations, as I showed, pass the ontological bench test, for they are fully mechanistic items.46

Finally, although the notion of directional configurations helps tie together some loose ends in Descartes’ theorizing, it does not by itself have the resources to address more general difficulties regarding Descartes’ understanding of light transmission. For example, what is one to make of the fact that streams of fire particles undoubtedly interfere with each other? Does Descartes expect one to believe that linear tendency remains unaffected by collisions with particles moving in opposing directions?47

Moreover, how does particle diffusion affect one’s perception of light? If fire particles deflect from circular surfaces, for example, then the lines of motion originating from the object’s outer edges (relative to the perceiver) might be thought to expand beyond the perceiver’s visual range. What is to stop this from happening by Descartes’ lights? I do not know any satisfying answers to these questions and those like them, and so simply leave them as that may or may not be capable of resolution. But one can at least take these as difficulties for Descartes’ theory generally, rather than a whole new set of problems introduced by directional configurations.

Thus, overall, according to my reading, Descartes mechanizes the Scholastic theory of light transmission, at least when it comes to physical causes. Like his predecessors, Descartes that emissions from external objects assimilate a medium so as to, in turn, assimilate sensory organs by way of physical contact. But, as I argued,

Descartes’ distaste for geometrically unintelligible motivates him to disavow

46 For further elaboration on Descartes’ insistence that Aristotelian forms and accidents be understood in an entirely mechanistic manner see Garber 1992, 103 – 111. 47 Interestingly, Nicolas Malebranche, in his arguments against intentional species, raises these sorts of concerns, although he says nothing about how they might burden Descartes’ mechanics. See LO 220 – 221. 40 the notion of intentional species, replacing it with something cast in the language of geometry—directional configurations. In the next chapter I discuss how directional configurations pass into the brain, and in doing so introduce the presentation thesis.

41

Chapter 2: Looking at the Surface of the Mind

Descartes qua metaphysician supposed that one’s conscious awareness, beliefs, and desires are immaterial features of reality. They are features of the soul, and little else.

Descartes qua natural philosopher believed that the human body was quite the opposite.

The human body, for Descartes, was “just a statue or machine made of earth,” equally automated as “clocks, artificial fountains, mills, and other similar machines which, even though they are only made by men, have the power to move of their own accord in various ways” (AT XI 119 / CSM 1 99 / G 99). But Descartes posits a link between mind and machine, locating the link in a specific part of the human body: the pineal gland, a tiny, porous organ at the center of the brain.48 This chapter is about the pineal gland’s role in sensory perception.49 The first section discusses Descartes’ views on brain physiology, specifically focusing on how Descartes’ mechanics of brain physiology relate to his theory of light transmission and visual perception generally. During the course of discussion, I introduce the presentation thesis, a thesis central to my interpretation. The second section concentrates on showing that the presentation thesis appears to span the breadth of Descartes' philosophical career. In the third section, I argue that the presentation thesis makes better sense than competing interpretations of Descartes’ Anatomical

Argument, a key argument for identifying the gland as the “seat of the soul.” The fourth

48 As is commonly known, throughout his entire career Descartes identified the pineal gland as the “seat of ” (for example, see AT X 176 – 177 / CSM 1 106 / G 149) and the “principal seat of the soul” (for example, see AT III 19 / CSMK 143). 49 For a condensed but informed summary of Descartes’ views on the pineal gland throughout his writings (and even its relation to the occult and Blavatsky’s “third eye”), see Lokhorst 2016. 42 section refines and defends the notion of impressional causation (briefly introduced in

Chapter 1) so as to smooth out the relevant metaphysics of the presentation thesis. In the final section I show that impressional causation helps respond to objections confronting the presentation thesis.

Section 1

The presentation thesis claims that the direct intentional object of perceived shape is a figure on the pineal gland’s surface, thus locating the intentional object in a mode of body. The thesis is about what minds directly attend to—what they are immediately presented with—when sensing shape. Descartes’ first clear statement of the presentation thesis occurs in his Treatise on Man, a work published posthumously in 1662, but a relatively youthful work nonetheless, written sometime between 1629 and 1633. The work as a whole is devoted to explaining the physiology of the human body, and includes detailed descriptions of the mechanics involved in visual sensory experience. These mechanics are the present concern.

The pineal gland is labeled ' H' in Figure 8 below. 50

50 This diagram originates from the Treatise. See AT XI 175 / CSM 1 105 / G 148. 43

Figure 8. The Pineal Gland

The gland is the hub of the body’s arteries, and functions as a tiny hose within the brain that constantly emits “a very fine wind” of rarefied blood—the so called “animal spirits”— outward toward complex arrangements of ocular endings. Thinking in terms of

Figure 8, the lines between H and the numbered tubes (to the right of the gland) represent the movement of animal spirits ejected from the pineal gland toward the “inside surface of the brain.”51 Each ocular nerve (numbered tube) is saturated with animal spirits

(as is the “space” between the pineal gland and the ocular nerve endings) and terminates in a valve like construction. When sensory experience occurs, originating from the back of eye travels through the , causing the valve openings to adjust accordingly. In terms of Figure 8, light rays deflected from the arrow (object ABC) redistribute pressure on the back of the eye at 1, 3, 5, in turn adjusting the valves located at

2, 4, 6.

51 Descartes actually uses the phrase “inside surface of the brain” a bit earlier in the Treatise when talking explicitly about the movement of animal spirits. However, it is quite handy, so I use it here. See AT XI 173 / G 146 (note: the relevant text is abridged from CSM). 44

Shortly after completing his comments on the diagram, Descartes writes that,

“Thus, just as the figure corresponding to that of the object ABC [the arrow] is traced on the inside surface of the brain depending on the different ways in which tubes 2,4,6 are opened, so that figure is traced on the surface of the gland depending on the ways in which the spirits issue from points a,b, and c [on gland H].” Descartes asserts here that an imagistic resemblance results from this mechanical process. He is saying that resembling figures form on the inside surface of the brain and, more importantly, on the surface of the pineal gland. This feature of Descartes’ theory thus gives reason to revisit the notion of directional configurations.

Directional configurations, as readers might remember, are second-order emergent properties. They are geometrical structures impressed on de facto surfaces, surfaces constituted by individual fire particles. As argued in the previous chapter,

Descartes appears committed to directional configurations because his theory otherwise lacks a mechanical account of how resemblances move from external objects into the plenum. The same sort of concern arises for the mechanical affairs within the head as well, for in the passage at hand, Descartes asserts that resemblances transfer from retinal surfaces into the brain. Moreover, there are two resemblances to consider, one on the brain’s interior surface and one on the gland’s surface. Overall, then, the notion of directional configurations is pertinent to the internal mechanics of vision, but some conceptual adjustments are nonetheless required.

Two adjustments need be made, one for the image on the inside surface of the brain and another for the image on the pineal gland’s surface. The modifications are slight regarding the former. The central difference between the notion of directional 45 configurations as presented in the previous chapter and as they are understood in relation the brain’s inside surface is a matter of what constitutes de facto surfaces. In the plenum, fire particles constitute these surfaces, but Descartes nowhere relates his theory of three elements to the human body, so there is no clear warrant for thinking that fire particles participate in the mechanical processes within the ocular nerves. Nonetheless, one can think of ocular nerves as miniaturized versions of the plenum and the brain’s internal surface as very much like a retinal surface, for Descartes appears to give no alternative.

The resulting view is, then, that animal spirits within the bundles of ocular nerves function as de facto surfaces responsible for transferring resemblances from retinal surfaces to the inside surface of the brain.52 And swapping out fire particles for animal spirits seems to apply to the pineal gland image as well, for the image also results from animal spirits colliding with a surface. However, as stated, the relevant bunch of animal spirits come from within the pineal gland, a feature of Descartes’ physiological views that requires a bit of care to reconcile with the notion of directional configurations.

To help illustrate the process by which pineal images are formed, I direct readers to the photographs below.

52 As mentioned earlier, this is how Sutton conceives of figures in the brain. See Sutton 1997, 63. 46

Figure 9. Pin Art Toy Model

Start State End State (Side View) End State (Front View)

These are three pictures of a pin art toy. The pictures represent two states of the process forming pineal images, namely a start state and an end state. For the sake of clarity, the end state is represented twice, once from the side perspective and once from head-on perspective. Moreover, as the labeling indicates, the photographs mean to represent four components of the process: (a) pins represent animal spirits within the pineal gland

(marked as “animal spirits within the gland”), (b) the surface through which the pins move represents the gland’s surface (marked as “pineal gland surface”), (c) the Plexiglas encasing represents the brain’s inside surface (marked as “inside surface of the brain”), and (d) finally the arrow represents the direction of motion (marked “motion direction”).

The photographs help visualize changes occurring on the pineal gland’s surface during

47 sensory perception and, moreover, show that the relevant process is unlike the process resulting in images on the brain’s internal surface. For, as the photographs illustrate, pineal images are produced by animals spirits being “pulled” from within the gland rather than having images “pushed” into it.

I labor over this difference because, according to how I have spelled things out so far, it might seem that directional configurations produce surface images only by propelling particles toward a surface. However, directional configurations are directly relevant to the pineal image as well, for directional configurations are second-order properties, and, as such, are not prohibited from multiple instantiations at the same time in discrete locations (in virtue of distinct causal processes). There are many mundane examples of such a thing. Just think, for example, about the produced paper or screen from which you read at this very moment—it is but one instantiation of presumably many.53 Similarly, although differing in causal process, there is little reason, at least in principle, to believe that the process producing pineal images cannot thereby result in the same shape that appears on the retinas and the inside surface of the brain.54

Overall, then, there are three internal resemblances realized in sensory perception: the retinal image, the image on the brain’s internal surface, and the image on the pineal gland. Each one, as Descartes claims here in Treatise and elsewhere, resembles an object out in the world, although the causal story of the pineal image is a little different than that of the other two. Among the three, though, pineal images are of most interest to the

53 Admittedly, there are likely microscopic differences, but that fact does not interfere with the main point of the example. 54 Although not labored over in detail in the main body, I take it that directional configurations are also part of the mechanisms required in imagination and memory since, as we will see shortly, figures on the gland’s surface are relevant for them as well. The one caveat that comes to mind, however, is that such directional configurations ought to be thought of as originating in the body, a story which merits its own attention. Given the general concerns, though, I do not attempt to such an account. 48 present investigations, for they are the direct intentional objects of perceived shape. They are the “figures,” “images,” “traces,” or “impressions” that minds directly “look at” when sensing shape. Let’s now examine why I take this as Descartes’ considered view.

Section 2

After Descartes explains the mechanical processes resulting in pineal images, he goes on in the Treatise to write,

Now among these figures, it is not those imprinted on the external sense organs, or on the internal surface of the brain, which should be taken as ideas—but only those which are traced in the spirits on the surface of gland H (where the seat of the imagination and the ‘common sense’ is located). That is to say, it is only the latter figures which should be taken to be forms or images which the rational soul united to this machine [the human body] will consider directly when it imagines some object or perceives it by the senses (AT XI 176 - 177 / CSM 1 106 / G 149).55

This is the first clear expression of the presentation thesis in Descartes’ corpus.56

Descartes here clearly states that pineal images are what souls “consider directly” when sensing an object, which, when put in contemporary classification, is a claim about intentionality. It is to say that pineal images are direct intentional objects, and therefore that minds are immediately directed to a mode of body. But considering the lessons from the previous section’s excursion into physiology, one should read Descartes’ claim about intentionality here as limited to visual shape perception, for pineal images are strictly geometrical in nature (as is resemblance). And, since the previous section provides the physiological details of what constitutes the pineal image, we are in a position to state the thesis in its most particular sense:

55 I consider the gland’s role as the common sense and in imagination shortly. 56 Allusions to something like the thesis appear in the Rules. However, the comments there fail to be as explicit as the remarks here in the Treatise. See AT X 415 / CSM 1 42. 49

Presentation Thesis: the direct intentional object of perceived shape is a pattern created by particles emitted through the body of the pineal gland and onto the pineal gland’s surface, i.e., the direct intentional object of perceived shape is a figure on the pineal gland’s surface.

Thus, as I read Descartes, minds are immediately directed to a figure on the pineal gland’s surface insofar as minds visually perceive shape. I want to be clear, though, about the extent of claim, especially in light of the fact Descartes’ definition of ‘figure’ in the Treatise commits to more than what presentation thesis alone commits to.

The definition of ‘figure’ in the Treatise is as follows,

And note that by figure I mean not only things that somehow represent the position of the edges and surfaces of objects, but also anything which, as I said above, can give the soul occasion to sense movement, size, distance, colors, sounds, smells, and other such qualities; and even things that can make it sense pleasure, , hunger, thirst, joy, sadness, and other such passions (AT XI 176 / CSM 1 106 / G 149).

Notice that Descartes divides the meaning of ‘figure’ into “things that somehow represent the position of the edges and surfaces of objects” and events that “occasion” phenomenal colors, sounds, smells, and so on. Descartes thus divides out perceived primary qualities from perceived secondary ones, and does so in a way that carves out the intentional from the causal. On the one hand, a figure on the pineal gland “represents the position of the edges and surfaces of objects” by directly presenting geometrical resemblances to the mind.57 This is a claim about intentionality, and little else. On the other hand, regarding perceived secondary qualities, Descartes ascribes causal roles to figures on the gland’s surface. He claims that movements of animal spirits (i.e. the motion of particles constituting the figure) “occasion” perceived secondary qualities, and this use of

“occasion” is undoubtedly causal, but it is not unproblematic.58

57 Sutton similarly understands the passage. He writes, “Descartes talks of imprinting, of figures and shapes: but it is obvious that these are not resembling images of dubious ontological status. ‘Figures’ are (transient) patterns of openness of brain pores, and the ‘parts’ of particular figures are the specific tubules which are jointly involved…” (Sutton 1997, 63). 58 Sutton notes this distinction in the role of figures as well. See Sutton 1997, 105 – 106. 50

To those familiar with early , “occasion” might direct one’s thoughts to any variety of occasionalist interpretations of Descartes.59 To give these readings fair due, I remain uncommitted to any particular way of understanding the term, and even aim to keep my hands clean on whether or not the passage is meant to endorse any occasionalist view whatsoever. However, it is necessary to acknowledge that, for

Descartes, the motion of particles constituting a figure, in one way or another, causally produce perceived secondary qualities. Such a causal commitment, though, does not mean, in and of itself, that motions on the pineal gland are not somehow an additional intentional object, but nor, on the other hand, does it mean that they are. As far as I understand the matter at this point, Descartes is only committed to a claim about the physiological components yielding perceived secondary quality—but he has yet to say anything about how the causal contribution of a figure’s motion relates to its role as an intentional object.60 Nonetheless, a general point remains true: figures are intentional objects insofar as they have shape and causal insofar as they have motion.

Now, the passages from the Treatise discussed in this section clarify some important issues. They help articulate the mechanics involved in the intentionality of shape perception, they affirm that minds are immediately directed toward figures on the pineal gland’s surface, and even pin down the role figures have in producing secondary quality perception (although with room for debate). Despite all this, the passages are not

59 In general, occasionalist views deny that, as generally conceived, causes constitute a “real action” but assert, on the other hand, that there is some intermediary between an “occasional cause” and its effect. In the next section I explain this view in more detail. See Nadler 2010, 32 – 35 for further elaboration. Additionally, for distinguishing between Descartes as endorsing either “limited ” or “thoroughgoing occasionalism,” see Ott 2009, 64. Finally, for what it means to read him as endorsing “occasionalism” as opposed to “occasional causation,” see Nadler 2010, 34. 60 Particular interpretive strategies taken up later in this chapter, however, force my hand on the relation between the figure’s causal contribution and its intentional one, although it is not in virtue of what Descartes says here in the Treatise. 51 enough to believe that Descartes adhered to the presentation thesis throughout the course of his career. Let’s thus move to providing some assurance to this thought.

It needs first be noted that, as the Treatise claims, the mind is directed toward figures on the gland’s surface either when it “imagines some object or senses it” (AT XI 177

/ CSM 1 106 / G 149; emphasis added). This close alignment between Descartes’ views on sensory perception and his views on imagination aids in deciphering where he avows the presentation thesis in his later writings, especially in detecting it in his most read work, the Meditations. For, in order to motivate the “probable conjecture” that bodies exist,

Descartes contrasts the faculty of pure understanding with the faculty of imagination, writing in the Sixth Meditation,

And I can easily understand that, if there does exist some body to which the mind is so joined that it can apply itself to contemplate it, as it were, whenever it pleases, then it may possibly be this very body that enables me to imagine corporeal things. So the difference between this mode of thinking and pure understanding may simply be this: when the mind understands, it in some way turns towards itself and inspects one of the ideas which are within it; but when it imagines, it turns towards the body and looks at something in the body which conforms to an idea understood by the mind or perceived by the senses (AT VII 73 / CSM 2 51).

This passage thus ascribes the presentation thesis to imagination, which should not be surprising given the physiological link between sensation and imagination asserted in the

Treatise. However, not all commentators detect the presentation thesis in this passage.

Margaret Wilson, for example, understands the Sixth Meditation as falling among those texts in which Descartes avers that “even experiences of particular shapes are not traceable to an instantiation in the brain of those particular shapes” (Wilson 1991, 296).

More to the point at hand, though, Simmons explicitly dismisses the above passage from the Sixth Meditation as for views like the presentation thesis, rejecting such readings on two grounds. She writes,

52

There are some competing passages in which Descartes suggests that the mind inspects images in the brain, the most famous of which occurs in his reflections on imagination in Meditation 6 (AT VII 73). This particular passage does little to confirm that Descartes’ considered view is that the mind can literally inspect images in the brain, for not only does he qualify the claim by saying the mind “as it were” (veluti) inspects the brain, but he also offers this account of imagination only as a possible explanation for how it works, not as the account he endorses (Simmons 2003, 561 fn. 27).

I address these two objections at length, and do so not only in defense of my reading, but also in order to broadly motivate my contention that Descartes adhered to the presentation thesis within the Meditations (and its Replies).

To begin, the criticism that Descartes “offers this account of imagination only as a possible explanation for how it works, not as the account he endorses” misses the mark on three counts for why Descartes treats it as just a “probable conjecture.” First, the

Meditations is set within the dialectical context of Descartes’ famed methodical doubt, a method having three broad and related components: (a) identify all that is worthy of doubt, (b) discover what can be known with certainty, and (c) justify otherwise doubt worthy beliefs on grounds of what can be known with certainty. As Descartes informs readers in the First Meditation, natural philosophy does not fall among things known with certainty, for “physics, astronomy, , and all other disciplines which depend on the study of composite things, are doubtful” (AT VII 20 / CSM 2 14). Thus, since

Descartes’ account of imagination is embedded within his mechanical theorizing, it too is worthy of doubt, and thus ought not to be catalogued as more than a “probable conjecture” (at least at the beginning of the Sixth Meditation).

The second reason that Descartes describes his account as “mere conjecture” is related to this point. It derives from the fact that he has yet in the Meditations to prove on sufficient grounds that material bodies exist. Such an argument does not occur until later

53 in the Sixth Meditation, where Descartes famously argues that bodies exist because, as one knows with certainty, God is not a deceiver. 61 Thus, at this point in the Meditations’ dialectic, he should treat his account of imagination as a mere hypothesis.

Finally, understanding Descartes in the Sixth Meditation as giving just a “possible explanation” for imagination weakens his purported goal for introducing imagination in the first place. In the opening of the Sixth Meditation, he claims that

The conclusion that material things exist is also suggested by the faculty of imagination, which I am aware of using when I turn my mind to material things. For when I give more attentive consideration to what imagination is, it seems to be nothing else but an application of the cognitive faculty to a body which is intimately present to it, and which therefore exists (AT VII 71 – 72 / CSM 2 50).

But it would certainly not be in Descartes’ best interest if he “suggested” that bodies exist on the grounds of a view that he does not himself find tenable.

Simmons’ second reason for not taking the passage from the Sixth Meditations at face derives from Descartes’ insertion of ‘veluti,’ or ‘as it were’. The ‘veluti’, however, turns out to be of questionable significance. In addition to indicating a metaphorical qualification, ‘veluti’ can mean “to connect, by way of example, a single instance with an established general proposition, as, for instance, for example” (Lewis and Short 1907, 1966).

Thus, the sentence at hand might alternatively be translated as “And I can easily understand that, if there does exist some body to which the mind is so joined, it can, for example, apply itself to contemplate it whenever it pleases.” According to this translation,

‘veluti’ indicates a particular consequence among many that results from the mind-body union. Three distinct considerations make this translation plausible.

61 See AT VII 79 – 80 / CSM 2 55 – 56. 54

First, the original construction of Descartes’ Latin is “ut ad illud veluti inspiciendum pro arbitrio se applicet.” This is an “ut-clause,” a clause of purpose or result.

Notice that ‘veluti’ appears after ‘ut ad illud’ (“in order to that”) but before the clause’s content. Word order being more a matter of choice than grammatical significance in

Latin, the ‘veluti’ can then apply merely to ‘inspiciendum’ or range completely over

“inspiciendum pro arbitrio se applicet.” Thus, within the original Latin one has grammatical justification for an alternative translation as the one suggested above.

Nonetheless, this point only demonstrates the alternative translation’s grammatical plausibility. A point more directed at the sentence’s intended meaning comes from the

1647 French translation of the Meditations, a translation approved by Descartes himself.

The French translation of the Meditations expresses the sentence as follows: “Et je conçois facilement que, si quelque corps existe, auquel mon esprit soit conjoint et uni de telle sorte, qu'il se puisse appliquer à le considérer quand il lui plaît, il se peut faire que par ce moyen il imagine les choses corporelles” (AT IXa 58). The French here does not include any clear metaphorical qualifier, especially in the relevant clause, “qu'il se puisse appliquer

à le considérer quand il lui plait.” Thus, if Descartes intended ‘veluti’ to signify metaphor in the Latin version of the Meditations, he failed to carry it over to the authorized French translation. Finally, consider a relevant passage from the Conversations with Burman.

According to the 1648 transcript, Burman asks Descartes directly about the meaning of ‘inscpicio’ in the sentence of interest from Sixth Meditation. Burman inquires,

What does ‘contemplate it’ [inspicere] mean? Does it mean the same as ‘to understand it’? If so, why do you use a different expression? If not, then the mind is more than an understanding or thinking thing, and even

55 before it has a body it has this ability to contemplate a body. Or is this ability of the mind an effect of its union with the body (AT V 162 / CSMK 344)? 62

The transcription records Descartes as replying,

It is a special mode of thinking, which occurs as follows. When external objects act on my senses, they print on them an idea, or rather a figure [figuram], of themselves; and when the mind [mens] attends [adverit] to these images imprinted on the gland in this way [imagines quæ in glandula inde pinguntur], it is said to have sensory perception. When, on the other hand, the images on the gland are not imprinted by external objects but by the mind itself, which fashions and shapes them in the brain in the absence of external objects, then we have imagination. The difference between sense-perception and imagination is thus this, that in sense- perception the images are imprinted by external objects which are actually present, whilst in imagination the images are imprinted by the mind without any external objects, and with the windows shut, as it were [tanquam] (AT V 162 / CSMK 344 - 345).

Although Descartes uses metaphor here, he does so in a blatantly metaphorical manner and not in regards to the concern at hand. Indeed, regarding the mind’s “attending,” the reply shows no metaphorical leanings, and in fact leans toward a more literal rendering of his claim in the Sixth Meditation. For Descartes does not mince words here about what he takes minds to be directed toward in imagination and sensation, visibly stating that minds attend (advert0) to “images imprinted on the gland.” This is as plain faced an endorsement of the presentation thesis that one can hope to get (and therefore coincidently suggesting that Descartes in fact approves of the “probable conjecture” given in the beginning of the Sixth Meditation).

These three considerations provide convincing reasons to accept the alternative translation of this passage from the Sixth Meditation and, in turn, motivate one to see the presentation thesis as part of Descartes’ theorizing in the Meditations as a whole.63 But in

62 The Conversations with Burman is sometimes thought to be of less reliability than other of texts since it was not penned by Descartes, being instead Burman’s own transcript. Nonetheless, much of what Descartes is recorded as saying lines up with what he says elsewhere. 63 If the above considerations do not satisfy some readers, then consider these two further points about the Sixth Meditation. First, here is a bit of the relevant passage once again with choice selections from the original Latin:

56 order to give evidence that Descartes held the presentation thesis throughout the entirety of his middle period writings—the Meditations era—I briefly discuss where one detects the thesis in his Replies.

In the Second Replies, Descartes means to standardize his definition of ‘idea’, writing that “Thus, it is not only the images depicted in the imagination which I call

'ideas'. Indeed, in so far as these images are in the corporeal imagination, that is, are depicted in some part of the brain, I do not call them 'ideas' at all; I call them 'ideas' only in so far as they give form [informant] to the mind itself, when it is directed towards

So the difference between this mode of thinking and pure understanding may simply be this: when the mind understands, it in some way turns towards [convertat] itself and inspects [respiciat] one of the ideas which are within it; but when it imagines, it turns towards [convertat] the body and looks at [intueatur] something in the body which conforms to an idea understood by the mind or perceived by the senses (AT VII 73 / CSM 2 51).

I draw attention first to the two uses of ‘converto’. The Lewis and Short translation of ‘converto’ is “to turn or direct somewhere, to direct to or towards, to move or turn to, etc” (Lewis and Short 1907, 464), and so, presumably, ‘converto’ indicates an intentional relation. However, the fact that Descartes uses it to describe instances in which minds are directed toward themselves or body suggests that ‘converto’ points to an intentional relation simpliciter, leaving aside questions about the ontological status of the intentional object. But next notice Descartes’ uses of ‘respicio’ and ‘intueor’ after the respective uses of ‘converto’. In its more literal sense, ‘respicio’ means “to look back or behind, to look about, look; to see behind one; to look back upon, to look at or for anything, look to” (Lewis and Short 1907, 1581), while ‘intueor’, in its more literal sense, has an obvious contrast to its counterpart, being “to look at, upon, or towards” (Lewis and Short 1907, 991). By including ‘respicio’ and ‘intueor’, Descartes thus demarcates two different directions in which minds can turn; they can turn “back” on themselves or out “upon” something else. Thus, reading this passage from the Sixth Meditation as not alluding to the presentation thesis does injustice to Descartes’ careful word choice. For within this single passage, Descartes not only draws out the concept of intentionality generally considered, but employs language meant to specifically contrast the two types of objects to which minds can be directed—they can “look back” on the mind itself or “toward” something in the body. This contrast is simply lost if the presentation thesis is removed from the conversation. Second, the beginnings of the Sixth Mediation is puzzling in a certain respect. It opens by tying imagination to the body in virtue of a special “contemplation” (inspicio) and then moves to convince readers that this contemplation applies to imagined shapes. But then after making this conclusion, Descartes abruptly transitions,

But besides that corporeal nature which is the -matter of pure mathematics, there is much else that I habitually imagine, such as colours, sounds, tastes, pain and so on—though not so distinctly. Now I perceive these things much better by means of the senses, which is how, with the assistance of memory, they appear to have reached the imagination. So in order to deal with them more fully, I must pay equal attention to the senses, and see whether the things which are perceived by means of that mode of thinking which I call 'sensory perception' provide me with any sure argument for the existence of corporeal things (AT VII 73 / CSM 2 51).

Astute readers of the Meditations might have some concern about this transition, for Descartes now discusses sensation proper, and is thus only talking about perceived secondary qualities. Why, then, has Descartes made a claim about intentionality in imagined perceived shape yet remained silent about intentionality in perceived sensory shape? Since neither the Sixth Meditation nor the Meditations as a whole has little else to say about the intentionality of sensory shape perception, it appears as if Descartes has ignored a crucial theoretical component. However, if one believes the Conversations and the Treatise, this absence turns out to be a dialectical oversight rather than philosophical one. That is, since imaginary perceptions are but sensory perceptions “with the windows shut,” Descartes does not owe readers much more than what he says at the Sixth Meditation’s outset.

57

[conversam] that part of the brain” (AT VII 160 - 161 / CSM 2 113). In the passage from the

Sixth Mediation just discussed, ‘converto’ is Descartes’ Latin word of choice for an intentional relation broadly conceived, a word meaning straightforwardly “to turn or direct somewhere, to direct to or towards, to move or turn to, etc” (Lewis and Short 1907,

464). As indicated, Descartes uses the very same word here, and is as explicit as he is in the Conversations about the object to which minds are directed. He claims that minds are directed to the “corporeal imagination,” yet another name for the pineal gland.64

In the Fifth Replies Descartes mentions the pineal gland’s relation to memory.

Descartes writes that “So long as the mind is joined to the body, then in order for it to remember thoughts which it had in the past, it is necessary for some traces of them to be imprinted on the brain; it is by turning to these [convertndo], or applying itself to them that the mind remembers” (AT VII 356 - 357 / CSM 2 247). Here again Descartes uses

‘converto’, and again directs minds to the brain itself. Moreover, this reference to the pineal gland’s role in memory is but a carry-over of the Treatise’s physiology. For soon after claiming in the Treatise that minds “consider” figures on the gland’s surface,

Descartes informs readers that brain lobes “store” such figures, and then writes,

That is why these figures are no longer so easily erased, and why they are preserved in such a way that the ideas which were previously on the gland can be formed again long afterwards without requiring the presence of the objects to which they correspond. And this is what memory consist in (AT XI 178 / CSM 1 107 / G 150).

The presentation thesis thus not only applies to sensory and imaginary perception—it applies to any visual-like shape perception, whether it be sensed, imagined, or

64 To my knowledge, Descartes never explicitly defines the corporeal imagination as the pineal gland. However, for Descartes, the corporeal imagination is that part of the body responsible for unifying sensory impressions—it is the commons sense—and thus must be the pineal gland. For his comments on the corporeal imagination, see, for example, AT X 414 / CSM 1 41 and AT XI 174 – 178 / CSM 1 105 – 106 / G 146 – 150. In addition, for those wondering about how the pineal gland might “form” thought, components of my interpretation from the fourth section can be thought to make sense of this. 58 remembered.65 Descartes even relates figures on the gland’s surface to one’s affective life, as is seen in the final pieces of textual evidence demonstrating the thesis’s longevity.

Descartes died three months after the publication of his . The work departs in many ways from his usual topics, focusing as it does on the affective dynamics of human life.66 Descartes is a systematizer par excellence, however, and so his thoughts on such matters are grounded in his mechanical physiology. When distinguishing between imaginary perceptions that “depend on the nerves” and those depending on “the fortuitous course of the spirits,” he writes in the Passions,

It remains to be noted that everything the soul perceives by means of the nerves may also be represented to it through the fortuitous course of the spirits. The sole difference is that the impressions which come into the brain through the nerves are normally more lively and more definite than those produced there by the spirits—a fact that led me to say in article 21 that the latter are, as it were, a shadow or picture of the former (AT XI 348 / CSM 1 338).

Notice Descartes’ claim that imaginary perceptions are just “a shadow or picture” of sensory ones, such “pictures” being synonymous with “impressions which come into the brain.” Thus, the figures of the Treatise are here in the Passions as well, but this time under the heading of “impressions.” But most worth attention for the present purposes is

Descartes’ use of ‘represent’ in the passage, for this word is found in those passages in the

Treatise from which the presentation thesis derives. As one might remember, Descartes wrote there that figures on the gland are things “that somehow represent the position of the edges and surfaces of objects,” suggesting, then, that here in the Passions he also claims that images in the brain “represent” objects to the mind in the same way.67 And

65 For a detailed discussion of Descartes’ views on the physiology of memory, see Sutton 1997, ch. 3. 66 One might conceive of ’s popular Descartes’ Error as a contemporary continuation of this line of thought. For Damasio’s discussion of how Descartes’ dualism might be seen to fit with relatively recent findings in , see Damasio 1994, 247 – 252. 67 See AT XI 176 / CSM 1 106 / G 149. 59 such imaginings can occasion joyfulness, as Descartes goes on to say in one of his most curious allusions to the presentation thesis.

Here is how Descartes conceives of joy in the Passions,

Joy is a pleasant which the soul has when it enjoys a good which impressions in the brain represent to it as its own....I add that the good is one which impressions in the brain represent as the soul's own, so as not to confuse this joy, which is a passion, with the purely intellectual joy that arises in the soul through an action of the soul alone... For as soon as our intellect perceives that we possess some good, even one so different from anything belonging to the body as to be wholly unimaginable, the imagination cannot fail immediately to form some impression in the brain, from which there ensues the movement of the spirits which produces the passion of joy (AT XI 396 - 397 / CSM 1 360 - 361).

Impressions in the brain are not the immediate cause of joy—that part belongs to the

“movement of the spirits.” Rather, impressions function as a sort of imagistic signifier,

“representing” a good in two ways. On the one hand, these impressions directly re-present some image or other just as they do in normal imaginings, yet, on the other hand, they signify a particular sort of ownership conducive to feeling joy. And so, even though the passages import is somewhat murky, it is a suggestive indication that the presentation thesis is alive in Descartes’ final writing, for he appears to rely on a presentational aspect of brain-impressions in these comments on imagination.68

The presentation thesis thus is not a mere youthful quirk. As I hoped to have shown, it is Descartes’ considered view, and seems to be at work in the background of the

Mediations and the Passions. And, although not my focus in the subsequent section, the thesis’ longevity will again be attested, for, as I argue, there is yet another place in the

Passions that is best read as alluding to the thesis. Indeed, this critical argument from the

Passions seems to make little sense without it.

68 I derive this reading of the passage from Wilson. See Wilson (1991), 307. 60

Section 3

In her “Descartes’ Pineal Gland Reconsidered,” Lisa Shapiro identifies two recurring types of arguments throughout Descartes’ corpus for his (in-)famous claims about the pineal gland. She labels one the “Anatomical Argument” and the other the

“Analogical Argument.” I focus on the former, and give attention exclusively to the version found in the Passions.69 I make this restriction for two reasons. First, considering that the Passions was penned within a year of Descartes’ , it serves as his final word on a central piece of reasoning. Second, the version from the Passions relies on examples pertinent to visual perception, and is thereby pertinent to the current investigations. I argue in this section that the presentation thesis contextualizes and therefore helps possibly render the Passions’ Anatomical Argument more intelligible.

Here, then, is the Anatomical Argument from the Passions:

Apart from this gland, there cannot be any other place in the whole body where the soul directly exercises its functions. I am convinced of this by the observation that all the other parts of our brain are double, as also are all the organs of our external senses—eyes, hands, ears and so on. But insofar as we have only one simple thought about a given object at any one time, there must necessarily be some place where the two images coming through the two eyes, or two impressions coming from a single object through the double organs of any other sense, can come together in a single image or impression before reaching the soul, so that they do not present to it two objects instead of one. We can easily understand that these images or other impressions are unified in this gland by means of the spirits which fill the cavities of the brain. But they cannot exist united in this way in any other place in the body except as a result of their being united in this gland (AT XI 353 / CSM 1 340).

The argument can be broken down in the following way:70

(1) Each retina has an image impressed on it.

(2) There are two retinas.

69 The argument presented in the Passions is but one of two species of the Anatomical Argument. See Shapiro 2011, 262. For earlier iterations of the relevant version of the Anatomical Argument see AT XI, 176 - 177 / CSM 1 105 - 106; AT III 18 - 19 / CSMK 143; AT VI 129 / O 100; and AT VII 86 / CSM 2 59 - 60. 70 For Shapiro’s rendering, see Shapiro 2011, 263. 61

(3) Hence, there are two images impressed upon the visual sense organs.

(4) But only a single visual image is perceived.

(5) Therefore, a bodily organ (in the brain) unifies images impressed on the retinas.

(6) The organ consolidating the images cannot be doubled.

(7) The pineal gland is the only brain organ not doubled.

(8) Therefore, the pineal gland unifies the two images impressed on the retinas.

The central issue I examine in the following section derives from the steps in premises (3)

– (5) of my reconstruction, that is, I examine the reasons why Descartes thinks an unpalatable consequence follows were impressions not unified in the brain. Stephen Voss has wondered about this too:

I admit that I find it hard to feel the force of this argument, because it is hard to make sense of the untoward consequence that Descartes fears if double impressions were to be transmitted unfused to the soul. Would the soul have two identical sensory images to consider? Would two copies of an identical proposition seek acceptance? A plausible reading of the argument would help answer the vexed question of the nature of sensory thoughts in Descartes, but unfortunately none seems forthcoming (Voss 1993, 134).

Voss is right in identifying the “untoward” consequence as he does: Descartes certainly appears to believe that souls would experience two identical (or at least extremely similar) imagistic perceptions were impressions not unified in the gland. But what puzzles me, and presumably Voss as well, is why Descartes is so casual about it. The “untoward” consequence certainly does not seem an obvious result.

In a footnote to her construction of the Anatomical Argument, Shapiro speculates about an unstated assumption that Descartes seems to incorporate within his reasoning:

Descartes thus seems to be operating under the basic premise that the soul itself has no power to combine the sensory impressions we receive from our different sense organs. All the synthesis of the multiple impressions from, say, the eyes, he presumes occurs within the body prior to any thought on the part of the soul (Shapiro 2011, 262 fn 12).

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This surely seems to be the principle at work in the argument. Unfortunately, however,

Shapiro restrains all mention of the principle to the footnote, leaving readers to wonder what reasons Descartes might have for this otherwise under motivated assumption. So, to make the goal of the next few pages a bit more precise, I ask: why does Descartes think that the brain rather than the soul unifies images? If there is not a good answer to the question, then responses like Voss’ seem warranted: the principle motivating the

Anatomical Argument deserves suspicion. But if sensible underlying reasons are found, then some sanity might be restored to the oft ridiculed Anatomical Argument. I begin thinking about this topic in, perhaps, an uncommon way, by identifying why some

Cartesian commentators appear committed to inserting this otherwise under motivated assumption into the Anatomical Argument. This requires a brief word about causation first.

Steven Nadler distinguishes between two causal views (among others) attributable to Descartes. The two worth noting for purposes here are “direct causation” and

“occasional causation.”71 To borrow Nadler’s description, direct causation is as such: “To say that A is the immediate and direct cause of B is to say that no thing exists or no event takes place between the cause and effect and serves as a causal intermediary between the two” (Nadler 2011, 31). Moreover, direct causation requires genuine transmission (or

“influx”) of some property given from the cause to the effect (one can think of the heat transmitted to their hand from a warm coffee cup). The contrast of direct causation is

“occasional causation,” and it lacks genuine transmission but nonetheless posits an intermediary event. Nadler broadly characterizes it as: “the term denotes the entire

71 Nadler calls the former “transeunt efficient causation.” In order to avoid introducing unnecessary terminology, however, I simply refer to it as “direct causation.” See Nadler 2011, 30. 63 process whereby one thing, A, occasions or elicits another thing, B, to cause e” (Nadler

2011, 33). The cause, A, does not transmit any property to B, but nonetheless triggers B to bring about some effect e.72 As readings of Descartes, however, these two views are unified in terms of their restrictions on the nature of causes in body-to-mind interaction.

Nadler describes the general causal relation (as opposed to direct or occasional causation specifically) in Descartes’ construal of body-to-mind causation as follows:

These motions [communicated by external bodies], after striking the sense organs, are in turn communicated through the nerves via the animal spirits to the brain and the pineal gland. The motions in the pineal gland are then followed by certain ideas and sensations. This correlation between brain motions and ideas is constant, lawlike, and involuntary (Nadler 2011, 38).

The two readings of Descartes on causation, then, are brought together by the fact that physical causes are limited to non-resembling causes. It is not in virtue of a figure’s shape that the pineal gland (in part) causes sensory perception, but rather simply in virtue of the motions of particles emitted from the gland.

These two styles of reading Descartes’ casual theory roughly covers the full breadth, and it is often thought that all Descartes has to say about body-to-mind interaction comes merely in causal terms (as opposed to being intentional as well). 73

Marleen Rozemond, for example, claims that Descartes’ view is “…that the union of the mind and body merely consists in their interaction, and that sensation is simply a mode of mind. On this view the role of the body is confined to causing occurrences of sensation”

(Rozemond 1998, 203). But if all physical causes are non-resembling, and body-to-mind

72 Nadler is careful to point out a few common misconceptions about occasional causation, one being that occasionalism (the view that God is the only true cause) is a particular form of occasional causation and that early moderns understood occasional causation to be as real as what I call “direct causation.” See Nadler 2011, 33 – 37. 73 For no accidental reason, the list commentators endorsing this view overlaps with those putting the “wedge” of sensory perception in the mind. I thus repeat it here. See Atherton 1990, 19 – 22; Kenny 1968, 222; Hatfield 1992, 354; Hatfield and Epstein 1979, 377; Maull 1978, 260; Machamer and McGuire 2009, 214 – 215; Schmaltz 2008, 159 – 160; Rozemond 1998, 173 – 174; Rorty 1992, 371 – 374; Simmons 2003 A and B, 556 – 559 and 420 en 8, respectively ; Wilson 1978, 1990, and 1999, 104, 8, and 23 respectively; and Wolf-Devine 1993 and 2000, 3 and 558, respectively. 64 interaction merely causal, then Descartes’ assumption in the Anatomical Argument that minds themselves cannot unify two impressions should appear under motivated. For, under these readings, the Anatomical Argument appears to commit Descartes to saying that, despite the soul’s power to convert mere motions into phenomenal qualities, the soul lacks an ability to convert doubled impressions into unified perceptions. But why should this be so, especially if the soul has other sorts of “black box” powers to change quantities into qualities? In other words, reading body-to-mind interaction as merely causal in conjunction with restricting physical causes to non-resembling ones does not sufficiently accommodate a key function that Descartes assigns to the pineal gland in his Anatomical

Argument.74 Since there appear no obvious restrictions on the mind’s powers of converting the physical into the mental, there is no clear reason for why Descartes attributes the power of unification to the body rather than the soul. One then cannot help but baffle over why this assumption occurs in the Anatomical Argument.

However, the reason Descartes assumes that brains (but not minds) unify impressions, I contend, derives from the fact that body-to-mind interaction is more than the process of non-resembling physical causes bringing about effects in the mind. Body- to-mind interaction also includes an intentional component, it requires that brains serve as an intentional object of sensory perception. One could, then, inject premise (4a) into the argument, it being “minds are directed toward their brain.” This premise thus happily

74 “Function” cannot be understood here as dependent upon . In keeping with Descartes’ prohibition on final causes, I do not intend “function” to be synonymous with some explanatory meaningful “purpose.” Descartes is no Aristotelian on this matter. So, my use of the term comes packaged with Cartesian trappings, namely that, when applied to the human body, talk of “function,” “use,” “purpose” and so on is nothing but a convenient way of speaking about a series of causal among particles. The pineal gland “functions,” then, in the same way as a clock’s hands show time—the function of “showing time”, like the function of “creating an image” on the pineal gland, is nothing more than one chapter in a narrative about particles in motion. Two further points are worth mentioning. First, I am not concerned with pinning down the precise notion of function at here. If the minimal understanding at hand, say, allows an explosion in the amount of bodily functions, so be it. Second, whether or not it is plausible for Descartes to eschew teleology in bodily interactions is a matter I do not seek to address. For comments on this topic, see, for example, Des Chene 2001, ch. 4. 65 leads to an additional conclusion: (9) the pineal gland is the intentional object of sensory perception. Accepting (4a) thus also gives reason for why Descartes identifies the gland as an intentional object in the first place: it is the only part of the brain that unifies impressions (and this, after all, is part of what it means for it to be the “common sense”).

One problem with this response, of course, is that 4a appears just as unmotivated as the assumption that minds do not unify impressions, and it should, as it just the other side of the coin. But seeing the other side of the coin at least helps one recognize textual precedence. Although Descartes does not explicitly provide independent grounds

(anywhere in his works to my knowledge) for the intentional relation between minds and their brains, it is at least something he commits to elsewhere in his writings. Thus, by highlighting this hidden assumption within the Anatomical Argument, yet additional evidence in favor of the presentation thesis emerges. Descartes assumes that minds do not unify impressions because he needs to front-load, so to speak, the brain with this function, and he needs to front-load the brain because the intentional object in sensory perception is the brain itself. So, in addition to passages we have already considered, there appears to be some less direct—but nonetheless enlightening—evidence that the presentation thesis is at work in Descartes’ last piece of academic writing.

Nonetheless, there is yet another obvious objection to my reading of the

Anatomical Argument. It might be thought that I have restored sanity by it in the bizarre. Some influential scholars think that the presentation thesis is plainly wrongheaded. Wilson encapsulates this sentiment when she writes,

The oddities of the presentational model are obvious. The model suggests that the mind perceives external bodies by virtue of perceiving, or otherwise recognizing, something else: traces or motions in the brain. But it neither explains how it is possible for the mind to do this, nor tell us why the question of how the mind does

66 this is not as legitimate as the original question about how perception of external things takes place (Wilson 1991, 308).

Wilson is no doubt correct on one count: explaining how minds “recognize” the gland is as important as explaining how perception works in general. But it is misguided to suggest that there is little one can do in order to develop a plausible and interesting account of how minds inspect the gland. I turn now to this critical concern.

Section 4

In the previous chapter I introduced the notion of impressional causation. The notion, one might remember, contains four claims about the causal relation between bodily surfaces:

(1) the affected thing and the affecting thing are bodily surfaces,

(2) both the cause and effect are geometrical configurations,

(3) the cause and effect resemble one another, and

(4) the relevant causal mechanism is contact (of sufficient motion) between bodily surfaces.

The notion was motivated by Descartes’ wax and seal example in Rule 12, the relevant passage being: “It should not be thought that I have a mere analogy in mind here: we must think of the external shape of the sentient body as being really changed by the object in exactly the same way as the shape of the surface of the wax is altered by the seal” (AT X

412 / CSM 1 40). In this section I expand on this notion, arguing that it applies not just to body-body interaction, but to body-to-mind interaction as well. I begin by returning to the Rules.

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The notion of impressional causation is grounded by Descartes’ claim that the wax and seal example is no “mere analogy.” The creations of retinal and pineal images are literally like the wax and seal: they are created by shapes impressing upon surfaces.75

However, later in Rule 12 Descartes transitions into using the wax and seal in a forthrightly analogical manner:

Fifthly, and lastly, the power through which we know things in the strict sense is purely spiritual, and is no less distinct from the whole body than blood is distinct from bone, or the hand from the eye. It is one single power, whether it receives figures from the 'common' sense at the same time as does the corporeal imagination, or applies itself to those which are preserved in the memory, or forms new ones which so preoccupy the imagination....In all these functions the cognitive power is sometimes passive, sometimes active; sometimes resembling the seal, sometimes the wax. But this should be understood merely as an analogy, for nothing quite like this power is to be found in corporeal things. It is one and the same power: when applying itself along with imagination to the 'common' sense, it is said to see, touch etc.; when addressing itself to the imagination alone, in so far as the latter is invested with various figures, it is said to remember; when applying itself to the imagination in order to form new figures, it is said to imagine or conceive; and lastly, when it acts on its own, it is said to understand ( AT X 415 - 416 / CSM 1 42 / all emphases mine).

Referring to the soul as the “cognitive power,” Descartes claims that it is “sometimes passive; sometimes active; sometimes resembling the seal, sometimes the wax,” and crucially adds that “this should be understood merely as an analogy.” But if the wax and seal example is not doing the explanatory work it did at the start of the discussion, then why is Descartes once again relying on it?

One disanalogy is clear: minds do not have bodily surfaces, so minds do not actually take on bodily impressions. This is why “nothing quite like this power is to be found in corporeal things.” And some sense of similarity is pellucid too: treating souls as if they receive bodily impressions gives some pull to the thought that perceived primary qualities resemble their causes. But I believe there is more to the analogy. I believe that

Descartes sticks with the wax and seal at this point in Rule 12 because he anticipates that the similarity should be understood a bit more literally. He suspects that he is committed

75 As noted in the previous section, in regards to pineal images the seal presses from within rather than without, so to speak. 68 to understanding body-to-mind interaction as involving a special form of impressional causation. And Princess Elisabeth is the one who finally brings this view and its consequences out of him.

In her May 1643 letter, Princess Elisabeth famously presses Descartes on mind- body interaction.76 She writes,

I ask you to tell me how the human soul can determine the bodily spirits to make voluntary actions (it being only a thinking thing). For it seems that all determination of motion takes place by the moved object being pushed, by the way in which it is pushed by what moves it, or by the qualification and shape of the surface of the latter. Touch is required for the first two conditions, extension for the third. You entirely exclude the latter from your notion of the soul, and the former seems to be incompatible with an immaterial thing (AT III 661).77

Elisabeth intends her criticisms to address mind-to-body interaction, but the specific problems she raises apply were she to inquire about how bodily motions interact with the soul because, being immaterial, the soul lacks the capacity to be touched or affected by the “qualification and shape” of moving particles. In his 21 May 1643 reply, Descartes hopes to address Elisabeth’s point by introducing “primitive notions,”

First I consider that there are in us certain primitive notions which are as it were patterns on the basis of which we form all our other conceptions. There are very few such notions. First, there are the most general— those of being, number, duration, etc.—which apply to everything we can conceive. Then, as regards body in particular, we have only the notion of extension, which entails the notions of shape and motion; and as regards the soul on its own, we have only the notion of thought, which includes the perceptions of the intellect and the inclinations of the will. Lastly, as regards the soul and body together, we have only the notion of their union, on which depends our notion of the soul’s power to move the body, and body’s power to act and cause its sensations and passions (AT III 665 / CSMK 218).

By positing primitive notions, Descartes acknowledges Elisabeth’s claim that neither the concept of body nor the concept of thought alone sufficiently illuminate body-mind interaction. Instead, Descartes says, the conceptual grounds for one’s understanding of

76 Shapiro argues that a philosophy of Elisabeth’s own can be worked out from her correspondences with Descartes. According to Shapiro, “In her view, the mind is autonomous—we are agents in our thinking and determine our own thoughts. Nonetheless, to be autonomous in this way, the mind depends on the good health of the body” (Shapiro 1999, 516). The general thought that mental independence and metaphysical dependency are consistent is one that, in regards to Descartes’ philosophy, I find inviting, especially given further developments in my reading. See Shapiro 1999 for further thoughts on how the two claims fit with one another. 77 Translated by Schmaltz. See Schmaltz 2008, 132. 69 body-mind interaction derives from the primitive notion of the mind-body “union,” a notion unique to itself. But in her 20 June 1643 letter, Elisabeth says that she finds this unhelpful, writing that, “I have to admit that it would be easier for me to attribute matter and extension to the soul than to attribute to an immaterial thing the capacity to move and be moved by a body” (AT III 685 / CSMK 220 fn 1). In his reply to this statement, I believe, Descartes acknowledges what was perhaps lurking in the back of his mind when writing the Rules.

He states in his 28 June 1643 correspondence with Elisabeth,

Your Highness observes that it is easier to attribute matter and extension to the soul than to attribute to it the capacity to move and be moved by the body without having such matter and extension. I beg her to feel free to attribute this matter and extension to the soul because that is simply to conceive it as united to the body. And once she has formed a proper conception of this and experienced it in herself, it will be easy for her to consider that the matter she has attributed to the thought is not thought itself, and that the extension of this matter is of a different nature from the extension of the thought, because the former has a determinate location, such that it thereby excludes all other bodily extension, which is not the case with the latter (AT III 694 - 695 / CSMK 228).

At first pass, Descartes appears to have entwined himself in contradiction: matter and extension now belong to the soul, and this mental matter is neither solid nor located in space. This apparent conundrum is worth pausing over.

First, there is an issue of whether or not Descartes adequately assuages Elisabeth’s concerns. Superficially, Descartes’ admission might settle things insofar as he posits a commonality between mind and body that, presumably, does away with the

“incompatibility” that vexes the princess. But were Elisabeth to press Descartes further

(which unfortunately she does not), she would no doubt point out that his admission does little to explain what happens when mind and body interact. Most obviously: what does it mean for an immaterial thing to be extended? Moreover, how can intangible, non- spatially located extension interact with physical stuff? Second, Descartes notes that 70 knowledge of this special form of extension derives from the primitive notion of the mind- body union. This is puzzling. For even if one sets aside questions about why this notion alone has this epistemic entitlement, there remain metaphysical perplexities. Is Descartes making a claim about what constitutes the mind-body union? And if so, what is the relation between the soul’s extension and bodily extension, and how might this relation account for the union?

There are good answers to these questions, but before getting to them, let’s clarify what Descartes cannot mean when attributing extension to the soul. In his 5 February

1649 letter, Descartes responds to Henry More’s worry that the definition of extension overgeneralizes, More’s particular worry being that the definition lumps God and angels among extended things. Descartes replies by writing,

It is not my custom to argue about words, and so if someone wants to say that God is in a sense extended, since he is everywhere, I have no objection. But I deny that true extension as commonly conceived is to be found in God or in angels or in our mind or in any substance which is not a body...Again, we easily understand that the human mind and God and several angels can be at the same time in one and the same place. So we clearly conclude that no incorporeal substances are in any strict sense extended. I conceive them as sorts of powers or , which although they can act upon extended things, are not themselves extended—just as fire is in white-hot iron without itself being iron ( AT V 269 - 270 / CSMK 361).

This passage offers forth fruit of temptation. It seems that Descartes reduces his meaning of mental extension to the commonplace thesis that immaterial things count as extended insofar as they have powers to affect or be affected by material bodies. But one should turn away from such temptation. On the one hand, Descartes is referring here to extension “as commonly conceived,” whereas his remarks to Elisabeth appeals to the primitive notion of the mind-body union, a different concept altogether. On the other hand, in his letter to

Elisabeth, Descartes suggests that, at least for created minds, the very powers at hand derive from the mind-body union. Thus, the very features appealed to in order to explain

71 away More’s worries are metaphysically grounded in the soul’s extension, at least if one is to believe what he wrote to Elisabeth.

So, then, what does it mean for minds to be extended? My first move in answering this question is controversial, yet especially fruitful. It is: minds are extended insofar as they have surfaces capable of being affected by impressions on the pineal gland’s surface.

I thus read Descartes as endorsing a special form of impressional causation exclusive to body-to-mind causation, and it is characterized in much the same way as its mundane counterpart:

(1) the affected thing and the affecting thing are surfaces,

(2) the cause and effect are geometrical configurations ( “impressions,” “figures,” “shapes,”

“images”, etc.),

(3) the cause and effect resemble one another, and

(4) the relevant causal mechanism is contact (of sufficient motion) between surfaces.

To begin making sense of how impressional causation applies to body-to-mind causation I now discuss Descartes’ views on bodily contact.

The notion of contact between bodily surfaces is, in my , one of the most intriguing components of Descartes’ philosophy (and that says a lot). For when one bodily surface contacts another, the two surfaces form a common boundary, and common boundaries have an incredibly peculiar ontology for Descartes. In his distinction between external and internal place from the Principles, Descartes writes the following about common boundaries:

Now internal place is exactly the same as space; but external place may be taken as being the surface immediately surrounding what is in the place. It should be noted that ‘surface’ here does not mean any part of the surrounding body but merely the boundary between the surrounding and surrounded bodies, which is no more than a mode. Or rather what is meant is simply the common surface, which is not a part of one body rather than the other but is always reckoned to be the same, provided it keeps the same size and shape (AT VIIA 48 / CSM 1 229). 72

Invoking the plenum, Descartes asks readers to imagine a saturation of particles in which every particle touches some other particle, and so there is always some “surrounding bodies” and “surrounded bodies.” As Descartes understands it, the boundary between these bodies is “not part of one body rather than the other but is always reckoned to be the same.” That is to say, there is a numerical between the common surface (or boundary) of body A and body B when the surfaces contact, a point which Descartes innovatively exploits in his debates on the nature of .

In his 9 February 1645 letter to Mesland, Descartes more explicitly carves out the ontology of common boundaries in hopes of reconciling his philosophy with Catholic . He writes,

In discussing the Blessed Sacrament I speak of the surface which is intermediate between two bodies, that is to say between the bread (or the body of Jesus Christ after the consecration) and the air surrounding it. By ‘surface’ I do not mean any substance or real nature which could be destroyed by the omnipotence of God, but only a mode or manner of being, which cannot be changed without a change in that which or through which it exists; just as it involves a contradiction for the square shape of a piece of wax to be taken away from it without any of the parts of the wax changing their place. This surface intermediate between the air and the bread does not differ in reality from the surface of the bread, or from the surface of the air touching the bread; these three surfaces are in fact a single thing and differ only in relation to our thought (AT IV 163 - 164 / CSMK 242).

As was the case in the Principles, common surfaces are catalogued as a mode of body that conjointly belongs to two individual bodies but belongs to neither one singularly. Thus, when bodies A and B are in contact, it is not as if there are three separate items—a surface of body A, a surface of body B, and a surface shared between A and B. Rather, there is one mode and it is common to both A and B.

Descartes continues in the letter by providing an account of what grounds the fact that shared boundaries form a numerically identical mode,

73

For if the body of Jesus Christ is put in place of the bread, and other air comes in place of that which surrounded the bread, the surface which is between that air and the body of Jesus Christ is still numerically the same as that which was previously between the other air and the bread, because its numerical identity does not depend on the identity of the bodies between which it exists, but only on the identity or similarity of the . Similarly, we can say that the Loire is the same river as it was ten years ago, although it is no longer the same water, and perhaps there is no longer a single part of the earth which then surrounded that water (AT IV 164 - 165 / CSMK 242).

It is not individual particles that make the Loire the same river it was years ago. Rather, the Loire’s identity is constituted by its “dimensions,” by the shape fashioned of its water and banks. By grounding the mode of bodily boundary (or common surface) in dimensionality instead of concrete particles, Descartes hopes to satisfy the Council of

Trent’s doctrinal formulation. As he writes to Arnauld in the Fourth Replies,

Now the teaching of the Church in the Council of Trent session 13, canons 2 and 4 is that 'the whole substance of the bread is changed into the substance of the body of Our Lord Christ while the form of the bread remains unaltered'. Here I do not see what can be meant by the 'form' of the bread if not the surface that is common to the individual particles of the bread and the bodies which surround them (AT VII 251 / CSM 2 175).

Descartes now takes himself capable of explaining why no outward change occurs in the

Host’s appearance despite an internal change: the surface of the bread just is the common boundary formed by the bread’s “surface” and the “surface” of surrounding air particles, and it matters not whether the particles “filling in” the Host are of the mundane or divine variety.78

As intriguing as it is, it is of little consequence whether or not this is a tenable fusion of Cartesian natural philosophy and Catholic . What is instead important for the purposes here is that this peculiar ontology of bodily boundary has striking ramifications for how one might understand the specifics of body-to-mind interaction in visual shape perception. On grounds of his letters to Elisabeth, I asserted that minds are

78 For further clarification on Descartes’ account of transubstantiation, see Bourg 2001 and Nadler 1988. 74 extended in a special way. Moreover, if one draws out the wax and seal analogy in Rule 12 a little further, this special type of extension seems to be that of having a surface— impressions need surfaces to impress upon after all. But if impressions impress upon minds, then the impression and mind share a common boundary. Thus, given that common boundaries are a numerically identical mode of two otherwise distinct things, one might conclude that the body and mind share a mode. This is a startling conclusion, so let’s pause here in the chain of reasoning to address some concerns.

One immediate objection to this line of reasoning is that it grounds a claim about the relation between body and mind in Descartes’ claims about the relation between body and body. My argument might then be thought to overgeneralize Descartes’ views. Since

Descartes nowhere explicitly says that what is true of bodily boundaries is also true of the boundary between mind and body, the objection holds some weight. However, I contend that applying Descartes’ comments on body-body modes to mind and body interaction has rewarding payoffs.

The application is fruitful on two counts. First and foremost, the thing achieved by positing a numerically identical, common boundary between mind and body is a more exacting explanation of how minds and bodies interact. The explanation, in a broad sense, is an ontological one. Two distinct kinds of substance are capable of interaction, at least in sensory perception, because they share an ontological item binding them together.

Thus, a puzzle about mind-body interaction receives some clarity because one is no longer left wondering how two separate substances can interact. However, this of explanation raises worries about whether or not the two substances remain distinct in kind if they share an instance of a particular mode. To address this worry, I bring 75 attention to another thing Descartes says in his comments on transubstantiation in the

Sixth Replies.

Descartes writes,

I do admit that one substance can be attributed to another substance; yet when this happens it is not the substance itself which has the form of an accident, but only the mode of attribution. Thus when clothing is the attribute of a man, it is not the clothing itself which is the accident, but merely ‘being clothed’ (AT VII 435 / CSM 2 293).

The special mode does not come about just in virtue of a substance being a mind or just in virtue of a substance being a body; one will not find this mode in disembodied minds or in un-minded bodies. The mode is the relation between mind and body, just as the mode of

“being clothed” consists in a spatial relation between clothes and one’s body. Thus, just as the man and his clothes remain truly distinct when he wears them throughout the day, the mind and body remain genuinely distinct when they are related to one another, at least by Descartes’ lights.

The second count of fruitfulness derives from the fact that positing this mode brings together some textual loose ends. In particular, positing a numerically identical common surface ties together the following strands of Descartes’ thought:

(1) Rule 12 suggests that impressional causation might have deep significance for understanding

the relation between minds and impressions on the surface of the gland,

(2) Descartes ascribes non-spatial, non-solid extension to souls, and

(3) the capacity of minds to be affected by bodily impressions derives

from the mind-body union.

It addresses (1) by introducing surfaces into the ontology of mind, thereby making impressional causation relevant to mind-body interaction. Consequently, (1) and (2) are tied together because, by giving minds a surface, one is also giving fuller meaning to the

76 notion of extended minds. Finally, (3) is linked to (1) and (2) since, at least for sensory perception, the mind-body union is constituted, in part, by the common boundary between mind and body.

Nonetheless, there remains a salient question confronting the idea that mind and body share a numerically identical mode: does this imply that a single mode is simultaneously material and immaterial? The immediate worry for thinking that something is both material and immaterial is that it straightforwardly violates the indiscernibility of identities, the logical principle that for any x and y, if x is identical to y, then x and y have all the same properties. Since, presumably, immateriality and materiality are mutually exclusive classifications, then it follows that the mode in question is not identical to itself. This is a real problem. However, I contend that Descartes can avoid it.

Descartes is not committed to claiming that the common boundary between mind and body is both material and immaterial. The reason Descartes avoids this problematic conjunction stems from the fact that, for physical bodies, common boundaries do not belong alone to either of the bodies forming the boundary. A point suggesting, as I take, that common boundaries do not necessarily inherit every property of the mutual bodies to which they belong. In the case of transubstantiation, for example, God might remove a batch of mundane square particles within the Host and replace them with divine smooth particles while simultaneously replacing, say, batches of triangle particles outside the Host with rhombus particles, all the while not making any change whatsoever to the common boundary between the Host and its surrounding particles.

77

But this example does not go far enough, for particles within the Host and particles without the Host are at least same in kind—they are both bodily in nature—and, thus, all the example shows is that a common boundary does not inherit every mode of the bodies it conjoins. Thus, what really needs assurance is that common boundaries do not necessarily inherit the essence or principal attribute of things they bring together.

However, I think assurance of this claim is yet another lesson derived from the man and his clothes. Central to Descartes’ example of the clothed man is the thought that the man does not actually become his clothes and that the clothes do not actually become the man.

Thus, when two substances are “attributed” to one another, they do not become one another. And so, at least by Descartes’ reckoning, one need not think that positing a numerically identical mode implies that the material becomes immaterial or vice versa.

But, one last question. If mind and body do not become one another, how can they share a numerically identical mode? This is a difficult and murky issue. However, it is more Descartes’ issue than mine. Descartes is straightforwardly committed to the notion that two things sharing a numerically identical mode do not—overall— form one thing, for his account of transubstantiation is lost without it. I thus leave this worry in

Descartes’ hands, hoping that an intelligible explanation lies hidden somewhere within his writings.

Now, I am not the first to read Descartes as positing a mode shared between mind and body. Paul Hoffman does as well, and he names such items “straddling modes.”79 I happily borrow this general description, but take care to note that, although Hoffman believes that Descartes posits modes straddling mind and body, he does not specify that

79 See Hoffman 2009, 108. John Cottingham also reads Descartes as endorsing this sort of mode. However, I use Hoffman here because his account is more pertinent to issues at hand. See Cottingham 1985, 229. 78 such modes are surfaces. Despite this discrepancy with my reading, though, much in

Hoffman’s work helps smooth out my interpretation. On the one hand, postulating straddling modes engenders a potential minefield of objections stemming from standard readings of Cartesian dualism. Although I addressed a few such objections above, I nonetheless refer readers to Hoffman, who more thoroughly addresses these worries than space allots here.80 But, on the other hand, Hoffman says some pertinent things about how one should conceive of straddling modes, and these points are well within the present scope.

Hoffman construes the unique ontological status of straddling modes as having conceptually distinct aspects, and he conceives of aspects in four different ways, each meant to make sense of why sensations (and imaginings, passions, etc.) qualify as modes of mind in certain respects despite belonging to a shared mode. He favors his third construal, and I do as well, for it resolves some worries to come. I quote it in full,

The third account is that a straddling mode is complex in another way, in being in two subjects at once. We might characterize its complexity as that of “having sides” like the concave and convex sides of a single surface. On such an understanding, it seems perfectly reasonable to say of a passion that even it is a straddling mode, in referring to that mode as a passion, we are picking out a certain aspect—that it exists in the patient. Similarly, even though an action is a straddling mode, in referring to it as an action, we are picking out another aspect—that it exists in the agent. And if this is acceptable—in other words, if it is acceptable to say that insofar as a straddling mode exists in the agent it is only an action and insofar as it exist in the patient it is only a passion—then it should be equally acceptable to say that a mode straddling mind and body is only a mode of thought on the mind’s side and only a mode of extension on the body’s side. Therefore, even taking a sensation itself to be a straddling mode presents no barrier to saying, as Descartes says in the Second Meditation, that sensing is nothing other than thinking, since that straddling mode is a sensation only on the mind’s side (Hoffman 2009, 114).

The general thought is that aspects are mere conceptualizations, mere manners of describing a single thing from different vantage points. To use Hoffman’s example, there exists only one curved glass, but it is describable as concave from one perspective and

80 For example, see Hoffman 2009, 101 – 124. 79 convex from another. Regarding my reading, then, the mind’s perception of figures on the gland’s surface count as a mode of mind insofar as it is the mind’s “side” of the straddling mode. On the other hand, figures impressed into the straddling mode’s surface qualify as bodily modes from the bodily “side” of things. Thus, in the end, the ontological status of sensory perception turns out, as a matter of fact, to be ontologically unique, and so ascriptions of it being either “bodily” or “mental” but handy ways of talking about one

“side” or other of the mode. And I want to be clear about why these aspects cannot be anything other than linguistic descriptions.

In and of themselves, minds do not have surfaces, just as particular bodies, in and of themselves, do not have common boundaries. Common boundaries, in their very nature, are ontological items constituted by x standing in a particular relation to y. Taking away the relation takes away the boundary. Nonetheless, common boundaries are ontologically robust items, not mere relational descriptions; they are as genuine as the motion of particles and one’s idea about the Pythagorean Theorem. And what gives warrant to posit such an ontologically committing relational mode on behalf of Descartes is the fact that a straddling mode is a common surface, and so exist just as much as its fully material counterpart.81 Strictly speaking, then, the only thing having a surface when it comes to the relation between mind and body is the mode grounded in and constituted by a particular mind related to a particular body in an appropriate way. Descartes’ appeal to the mind’s extension in his letters to Elisabeth, then, is not an appeal to a mode of mind simpliciter; he is not referencing anything like a thought. Rather, Descartes appeals to an

81 In criticizing Cottingham’s reading, David Yandell claims that “What he [Cottingham] does not take adequate note of is that the attribute in question—that of union—is a relation between two substances, not a third non-relational attribute resting in some mysterious way on the other two” (Yandell 1999, 207). This objection faces my reading as well. However, in response, Yandell appears to build this argument on the assumption that relational attributes are not real in any sense. But Descartes’ comments on common boundaries dismisses this assumption, I believe. 80 ontological item emerging from God’s action of relating this mind to that body, and this mode is describable from a bodily aspect or mental one, just as a bodily boundary can be described from the vantage of the body on the left or the body on the right. But, nonetheless, since the straddling mode does not fall out of minds or bodies alone, it can only be an ontological fact constituted by and understood through the union of mind and body. When speaking from an ontological standpoint, then, a straddling mode has two distinct aspects but not two distinct .

The straddling mode can also be considered from a causal standpoint, a standpoint that introduces two further aspects of straddling modes. As Hoffman recognizes,

Descartes maintains an identification of action and passion, a view Descartes states at the outset of the Passions,

In the first place, I note that whatever takes place or occurs is generally called by philosophers a ‘passion’ with regard to the subject to which it happens and an ‘action’ with regard to that which makes it happen. Thus, although an agent and patient are often quite different, an action and passion must always be a single thing which has two names on account of the two different subjects to which it may be related (AT XI 328 / CSM 1 328; emphasis added).82

When Descartes asserts here that “we should recognize that what is a passion in the soul is usually an action in the body,” he uses the “is” of identification—the pineal gland’s action on the mind just is the mind being affected. In the Passions, Descartes thereby conceives of causation not as a relation between two distinct events, but rather a single event that has two descriptions or aspects. Straddling modes thus have an aspect of being a cause and an aspect of being an effect.

Understanding straddling modes as causes, at least in regards to sensory perception, brings the mechanical particulars of the pineal gland back into the discussion.

82 Hoffman understands this feature of Descartes’ philosophy as integrating an Aristotelian view of causation. See Hoffman (2009), 106 - 107. 81

As explained earlier, particles moving through the gland’s surface produce a figure, and this figure, I claimed, is the direct intentional object of perceived shape. In the strictest sense, however, the direct intentional object is actually the figure as impressed into the straddling mode’s surface and, in turn, as “impressed” into the mind. In this manner, straddling modes can be thought of as the stopping point of directional configurations; they are the final impressed and impressing surface. On the other hand, the effect of this action is the mind’s perception of or attending to shape. And, as Descartes’ identification of action and passion dictates, the mind’s perception is one and the same as the action of the straddling mode, for there is but one event, an event that can be conceived (but merely so) as having a distinct cause and a distinct effect. Finally, there is yet one more

“effect” that straddling modes concomitantly produce: the effect of perceived color.83 Like perceived shape, perceived color is produced by a straddling mode’s impression.

However, the direct cause of perceived color is not the impression’s shape. Rather, as the

Optics teaches, the cause is a particular motion of those particles constituting the impressed figure. The surface of a straddling mode thus also takes on motion and, in turn, converts that motion into perceived color in such a way that the figure appears as colored.84

83 One benefit of making perceived color a direct effect of the straddling mode is that some sense can be made of Descartes’ claim (written to Elisabeth) that one knows the mind-body union through sensation, for to experience color is thus to directly experience the straddling mode. However, there is a notable problem with this claim in light of Descartes’ views on the epistemic status of sensation (proper). I owe this idea and its Cartesian criticism to Schmaltz. See Schmaltz 1992, 298 for his presentation of this idea. 84 Working out the precise account of how perceived color “maps” onto perceived shape is complex, and requires much more discussion of Descartes on color than can be allotted here. However, because I think it difficult to conceive of color as an “additional” intentional (and therefore ontological) item to which minds attend in shape perception, I lean toward an adverbialist or eliminativist reading of perceived color. For whether or not adverbialism makes sense within a Cartesian context see Ott 2014. For an eliminativist reading of Descartes on perceived color, see Pessin 2009. MacKenzie’s distinction between “intentional presence” and “phenomenal presence” is also worth considering in relation to this point. See MacKenzie 1989, 181 – 187 82

Overall, then, the presentation thesis is but one way (of many) of conceiving of straddling modes. It is the conception of straddling modes from the standpoint of causation and, more specifically, from the aspect of an effect, an effect which presents the figure on the pineal gland’s surface to the mind. This is what it means for minds to “look at” the gland in the most refined sense.

“ end somewhere” (PI 1), as Wittgenstein wrote in his Philosophical

Investigations. Here, I believe, is where the explanation ends. We have arrived at the bedrock of Cartesian mind-body interaction in visual shape perception. Nothing remains to be told about how the pineal gland interacts with the mind, and so we have reached a brute fact. But this fact can be spoken about in a number of ways, and these ways of speaking have some broad ramifications.

Section 5

The presentation thesis is often ridiculed in light of its apparent mysteriousness.

Wilson, as I noted, suggests that Descartes offers little in order to explain how minds can possibly recognize traces in the brain. I hope to have dismissed this worry by way of what

I said in the previous section. And I hope, more generally, that readers can see why the presentation thesis is more nuanced than first appearances let on. On my reading, it remains true that minds directly attend to figures, but these figures now belong to a straddling mode, not the gland in and of itself. Thus, the language of “looking at,”

“considering,” and “turning toward” that Descartes so often employs when asserting the thesis turns out to be facon de parler in a certain sense. These ascriptions make it sound 83 as if Descartes’ theory of visual perception postulates that souls look out upon an ontological item entirely different in kind from the mental. This is not true in a technical sense, at least according to my reading. For although minds directly apprehend impressions, they apprehend them by standing atop the bridge between mind and body, and so do not come into direct contact with the brain itself. Nonetheless, I will continue to speak as Descartes does, as if straddling modes are taken for granted and as if minds peer directly upon the brain.

Moreover, the introduction of straddling modes, as one might gather, has some important ramifications. Most notably, it suggests that Descartes’ dualism should be reconsidered on at least two counts. First, minds and bodies should not be thought of as isolated metaphysical hemispheres. For the two are connected in an ontologically significant way: they share a mode with one another. Thus, second, the thought that, in general, modes must belong exclusively to bodies or exclusively to minds deserves reconsideration. For if one accepts my reading, then positing a mode common to both substances is a viable means of accounting for the intentional relation between mind and body and, more broadly, accounting for how minds are aware of a reality outside the mind.

In addition, my reading avoids yet another common objection to the presentation thesis, namely the objection that the thesis commits a version of the homunculus .

Anthony Kenny first coined this particular flawed way of thinking and describes it as such,

“I shall call the reckless application of human-being predicates to insufficiently human- like objects the homunculus fallacy, since its most naïve form is tantamount to the postulation of a little man within a man to explain human experience and behavior” 84

(Kenny 1968, 65 - 66). Putting a tiny man in the mind as an explanation of visual perception has two closely related flaws. The first flaw is that it is a vacuous and circular explanation: to posit yet another perceiver as an explanation for perception grounds the explanans in the explanandum. The second flaw is that it generates an infinite regress: if positing a tiny man in the mind is the endgame strategy, then one need posit a tinier man within the tiny man so as to explain the initial tiny man’s perception, and so on ad infinitum. But by identifying causation with intentionality I avoid circularity and infinite regress. The identification of the two avoids circularity because it is not attempting to explain a perceptual act by appealing to yet another perceptual act. Rather, visual perception is explained in terms of causation: to visually perceive shape just is to be directly acted on by a figure, and so the explanandum is distinct from the explanans. And this blocks the regress as well, for, since visual perception no longer explains itself, one need not make the initial step into infinity.

Finally, it is worth noting that, as I understand my reading, Descartes is not committed to . He is not adding the substance of the mind-body union to his list of substances.85 My reading fails to fall among trialist readings because I do not claim that straddling modes are capable of independent existence. As I conceive of them, straddling modes are indeed just modes: a modification that depends on substance for its existence.

Such modes are certainly unique insofar as they require two modes for their existence, but

85 For an overview of different conceptions of trialism and the particular claims to which they might be committed, see Zaldiver 2011, 395. 85 this fact alone is not enough to make it metaphysically independent in the relevant way.86

If my view is a trialist one, then it must be so in virtue of features I do not consider here.

In this chapter I explained the textual motivations for and conceptual machinery of the presentation thesis. However, I did not address one of the thesis’ most discussed hurdles, the contention that Descartes outright denies it. I now turn to this problem.

86 My reading thus falls in line with John Cottingham’s, who commits to mixed modes but not three substances. See Cottingham 1985, 229. 86

Chapter 3: Combating the Eyes in our Brain

Descartes begins the Sixth Discourse with,

Now although this picture, in being so transmitted into our head, always retains some resemblance to the objects from which it proceeds, nevertheless, as I have already shown, we must not hold that it is by means of this resemblance that the picture causes us to perceive the objects, as if there were yet other eyes in our brain with which we could apprehend it; but rather, that it is the movement of which the picture is composed which, acting immediately on our mind inasmuch as it is united to the body, are so established by nature as to make it have such perceptions; and I would like to explain this to you in more detail (AT VI 130 / CSM 1 167 / O 101).87

Contemporary responses to this passage are fairly consistent. Descartes is read as plainly rejecting views like the presentation thesis when he writes that it is not “as if there were yet other eyes in our brain with which we could apprehend” the picture “transmitted into our head.” Margaret Wilson, for example, states,

In this important text, Descartes himself makes fun of the idea that there are “other eyes in our brain” with which we perceive the images that form there. In this passage, the rejection of the conception of perception in terms of transmission of pictures or replicas extends, it seems, to a general rejection of the presentation model (Wilson 1991, 310).88

And Tad Schmaltz similarly claims,

In this earlier text [the Optics], appended to the 1637 Discourse, he argues that we do not perceive an object by viewing pictures of it in the brain, “as if there are other eyes in our brain with which we could perceive it.” The concern here is to argue that the mind does not come to have the perception by viewing pictures composed of motions in the brain (Schmaltz 2008, 156).89

87 Since it will be of some concern in this chapter, unless explicitly noted, I use Olscamp’s translation of the Optics. 88 While it is true that Wilson only claims that “it seems” that Descartes rejects the presentation model, she does not go on to explain why one should not read the passage as such. 89 For a small sample of others who endorse this reading see, Arbini 1983, 326, fn 14; Alanen 2003, 142 – 143, en 16; Machamer and McGuire 2009, 212; MacKenzie 1990, 133; Maull 1978, 258, fn 17; Simmons 2003A, 561; and Wolf-Devine 2002A, 509. 87

Nonetheless, I contend that this is one place where first appearances are misleading. The reason is three-fold. First, what Descartes has “already shown” in previous sections of the

Optics is consistent with the presentation thesis. Second, the original French rendering suggests that an important distinction resides in the passage itself that, in turn, recommends an alternative interpretation. Finally, what Descartes explains “in more detail” within the remainder of the Optics is also consistent with the presentation thesis, and, indeed, some passages are rendered more intelligible by it.

Accordingly, in this chapter I argue that the Optics does not yield sufficient textual evidence for supposing that Descartes means to reject the presentation thesis in his comment about “eyes in our brain,” and that more generally he is not attempting to replace the Treatise’s account of shape perception with a natural model (the particulars of which will be explained shortly). Nonetheless, as I show, the Optics enriches the theory given in the Treatise by positing additional mechanisms accounting for the physiological basis of intellectual evaluations about visual content. I conclude this chapter by discussing how Descartes’ introduction of the three grades of sensation in the

Sixth Replies fits with his overall views of sensory perception. Contrary to popular interpretations, I argue that the Sixth Replies is not meant to explain how sensory experiences are produced, but rather, just as it was in the Optics, Descartes’ interest is to explain the role sensory experiences play in intellectual evaluations.

88

Section 1

Descartes’ claim that it is not “as if there were yet other eyes in our brain” is a problem for my reading. It seems as if he is simply denies the presentation thesis.90 But this is only a problem, I contend, if one can locate a specific argument for why he denies it in what precedes the passage or what comes after it. In this section I discuss what precedes it, aiming to show that what Descartes has “already shown” in the Optics is not at odds with the thesis. Since the Fourth and Fifth Discourses are the only two previous chapters within the Optics to have mentioned anything about the pineal gland, I restrict the discussion to them. Let’s thus examine them accordingly.

In the Fourth Discourse, Descartes writes that,

… it is necessary to beware of assuming that in order to sense, the mind needs to perceive certain [quelques] images transmitted by the objects to the brain, as our philosophers commonly suppose; or, at least, the nature of these images must be conceived quite otherwise as they do. For, inasmuch as the philosophers do not consider anything about these images except that they must resemble the objects they represent, it is impossible for them to show us how they can be formed by these objects, received by the external sense organs, and transmitted by the nerves to the brain (AT VI 112 / CSM 1 165 / O 89).

In cautioning the reader against the view that “the mind needs to perceive certain images,” it might appear that this is the prior denial. However, notice that Descartes is not denying—full stop—that minds perceive images transmitted into the brain. He instead claims that minds need not perceive “certain [quelques] images…as our philosophers commonly suppose.” There is little reason not to believe that the “philosophers” he refers to are none other than the Scholastics meaning, consequently, that the “certain images”

90 One might think that this statement is not the most direct way of denying the presentation thesis since Descartes says that we do not have “eyes in our brains” rather than “eyes in our minds.” I endorse this thought, but set it aside because commentators often understand the former as, more or less, meaning the latter. 89 are none other than “those small images flitting through the air, called intentional species”

(AT VI 85 / CSM 1 154 / O 68 ). Descartes’ gripe in this passage, then, does not apply to just any theory supposing that minds are directed toward brain states. Its specific target is the Scholastic model, a model supposing that minds directly attend to quasi-material things that are constitutionally imagistic.91 And Descartes finds such a theory unpalatable because he finds it “impossible” for the Scholastics to explain how “certain” images are

“transmitted by the nerves to the brain.” That is, he opposes any sort of (supposed) picture model of perception that conjointly posits little non-mechanical, irreducible images flitting about. Such a view is not the presentation thesis.

Descartes goes on in the Fourth Discourse to criticize the Scholastics in a way that might be interpreted as more forcibly opposed to my reading. He states,

And they have had no other reason for positing them [images transferred into the brain] except that, observing that a picture can easily stimulate our minds to conceive the object painted there, it seemed to them that in the same way, the mind should be stimulated by little pictures which form in our head to conceive of those objects that touch our senses; instead, we should consider that there are many other things besides pictures [autres choses que des images] which can stimulate our thought, such as, for example, and words, which do not in any way resemble the things which they signify (AT VI 112 / CSM 1 165 / O 89).

This passage is likely the one Descartes had in mind when referring to what he had

“already shown” prior to the Sixth Discourse, for he is directly concerned with views claiming that “the mind should be stimulated by little pictures which form in our head.”

However, there are some things that get in the way of reading this as a denial of the presentation thesis.

91 See Chapter 1 for a more thorough discussion of the ontology of intentional species. Also, it is worth noting that Anthony Crifasi has done some interesting work regarding the parallel between Descartes’ comments in the First and Fourth Discourse. See Crifasi 2011, 142. 90

On one count, Descartes seems most interested here in dismantling theories that model visual perception as if it were just a matter of looking at resembling images or pictures. For instead of buying into the picture model of the Scholastics, Descartes avers that one should “consider that there are many other things besides pictures [autres choses que des images] which can stimulate our thought, such as, for example, signs and words, which do not in any way resemble the things which they signify.” Descartes’ claim that there are “things besides pictures” is important because it indicates that something more than resembling pictures is relevant to visual perception, which, of course, does not jointly dictate the stronger claim that pictures in the brain have no role in producing sensory experience whatsoever. In other words, Descartes’ emphasis suggests that the physical causes of visual perception include in addition non-resembling causes, not merely non- resembling ones. This point is further evidenced by Descartes’ use of the “words and signs” analogy in the passage.

One of the earliest uses of the analogy is found in the Treatise on Light, written two years before the publication of the Optics. As Descartes ponders early in the work,

Now if words, which signify something only through human , are sufficient to make us think of things to which they bear no resemblance, why could not Nature also have established some which would make us have a sensation of light, even if that sign had in it nothing that resembled this sensation (AT X 4 / CSM 1 81 / G 3)?

Descartes claims here that the sensation of light is just like the sensations of color, pain, and sound. Descartes thus refers here to “sensation” in the technical sense (described in the Introduction), that is, as non-resembling perceived secondary qualities, or what I call

“sensation proper.” For, as Descartes says in the Principles, where he once again employs the analogy, 91

It can also be proved that the nature of our mind is such that the mere occurrence of certain motions in the body can stimulate it to have all manner of thoughts which have no likeness to the movements in question. This is especially true of the confused thoughts we call sensations or feelings. For we see that spoken or written words excite all sorts of thoughts and in our minds...A sword strikes our body and cuts it; but the ensuing pain is completely different from the local motion of the sword or of the body that is cut—as different as colour or sound or smell or . We clearly see, then, that the sensation of pain is excited in us merely by the local motion of some parts of our body in contact with another body; so we may conclude that the nature of our mind is such that it can be subject to all the other sensations merely as a result of other local motions (AT VIIIA 320 - 321 / CSM 1 197).

Thus, when Descartes rejects in the Fourth Discourse the notion that minds are

“stimulated by little pictures” in the brain, he does not obviously reject the view that one finds in the Treatise on Man, Meditations, and the Passions, for he does not specifically disavow an intentional relation between minds and body when it comes to perceived shape. Rather, he ridicules the notion that visual perception is merely produced by resembling causes. Thus, one may suppose that Descartes is saying that the Scholastic picture model is not the full story because such a model does not account for perceived secondary qualities.

After the “words and signs” analogy, the narrative of the Fourth Discourse makes a curious turn. For, after directing the reader’s attention to non-resemblance by introducing the words and sign analogy, Descartes returns to the issue of resemblance, writing “And if, in order to depart as little as possible from currently accepted beliefs, we prefer to avow that the objects which we perceive truly transmit their images to the inside of our brain, we must at least observe that there are no images that must resemble in every respect the objects they represent” (AT 112 - 113 / CSM 1 165 / O 89 - 90).92 This transition is worth noting for two reasons. First, it suggests some reservation about entirely barring resembling images in the brain, and, indeed, as one sees at the conclusion

92 Nancy Maull finds this transition “puzzling” because, as she reads the Optics, Descartes has completely done away with the presentation thesis. This puzzle no longer persists if my reading is endorsed. See Maull 1978, 261. 92 of the Fifth Discourse, Descartes appears inclined to carry over the Treatise on Man’s mechanistic account of internal resemblances.93 So, if the Fourth Discourse is read as doing away with the presentation thesis, then one is stuck with a physiology designed for mental inspection yet with no mental inspection to be had, a rather uncharitable position to put Descartes in.

The second reason the transition should arouse attention is that it indicates a modification of Descartes’ positive views on the nature of resemblance. The point of returning to resemblance, Descartes says, is to make readers aware that images within the brain “resemble the objects in but a few ways, and even that their perfection frequently depends on their not resembling them as much as they might” (AT VI 112 – 113 / CSM 1 165

/ O 89 – 90), a claim appearing to depart from the Treatise’s official view that pineal images “correspond exactly to the shape” of their objects. So, then, to what degree is

Descartes revising his position?

The answer is found within the engraving analogy,

For example, you can see that engravings, being made of nothing but a little ink placed here and there on the paper, represent to us forests, towns, men, and even battles and storms, even though, among an infinity of diverse qualities which they make us conceive in these objects, only in shape is there actually any resemblance. And even this resemblance is a very imperfect one, seeing that, on a completely flat surface, they represent to us bodies which are of different heights and distances, and even that following the rules of perspective, circles are often better represented by ovals than by other circles; and squares by diamonds rather than by other squares; and so for all other shapes. So that often, in order to be more perfect as images and to represent an object better, they must not resemble it (AT VI 113 / CSM 1 165 - 166 / O 90).

As one can see, there is a clear point of contact between this analogy and the physiology

Descartes posits in the Treatise: resemblances between images in one’s head and their objects are resemblances in shape. But one gathers from the engraving analogy that

93 See AT VI 129 / 0 100. This particular passage mentioning the common sense is not included in CSM. However, CSM does include the Fifth Discourse in abbreviated form. See CSM 1 166 - 167. 93

Descartes now wants these images to be “very imperfect” so as to “represent an object better”; that is, he conceives of this resemblance as now containing perspectival . Thus, resemblances in the brain and, mutatis mutandis, resemblances in the eye resemble from some vantage point. It is easy to see why Descartes eagerly makes this modification.

The account of directional configurations I laid out in the first chapter ascribes the origin of a configuration’s shape to an object’s surface structure, a claim still true here.

However, the proffered account fails to consider that a perceiver's spatial relation with the perceived object also contributes to the shape of impressions. For example, the retinas of someone looking head on at the rim of a teacup from an observational angle of, say, fifteen degrees will receive a more elliptical impression than when they perceive it head on from the same distance but from an observational angle of forty-five degrees, seeing the teacup’s rim as more circular this time. In short, the angle from which one perceives an object affects the shape ultimately impressed on the retinas and, in turn, affects the shape impressed on the gland. Thus, directional configurations encode perspectival information, but such information depends on the angular relation between perceiver and the perceived object.

In effect, the overall purpose of the resemblance talk in the Fourth Discourse is not to reject views like the presentation thesis.94 It is to show, on the one hand, that resemblance is not the sole cause of visual perception, a doctrine that Descartes already committed to in the Treatise, claiming there that figures on the gland’s surface also “give

94 So as to avoid being accused of ignoring an important sentence, it should be noted that Descartes opens the Fifth Discourse by writing “Thus you can clearly see that in order to perceive, the mind need not contemplate any images resembling the things that it senses” (AT VI 113 / CSM 1 166 / O 91). I address this passage in the next section. 94 the soul occasion to sense movement, size, distance, colors, sounds, smells, and other such qualities” (AT XI 176 / CSM 1 106 / G 149). On the other hand, the purpose of the

Fourth Discourse is to modify the Treatise’s account of resemblance so as to mechanize perspectival information, a move enriching rather than supplanting Descartes’ earlier work.95 Nonetheless, there does appear to be a transition between the Treatise and the

Optics in how Descartes conceives of the gland’s role in visual sensory experience.

As one sees in the passage from the Treatise cited in the previous paragraph,

Descartes seems to give the gland sole responsibility of things like distance and size perception.96 As I argue later in this chapter, the Optics appears to continue to attribute these perceptual qualities to the gland insofar as they are phenomenal characteristics.

Nonetheless, Descartes’ views on these perceptual features—especially distance and size perception—undergoes some refinement, for he wants to show that the gland is not responsible for everything, particularly one’s judgments about visual phenomenal qualities. One can, then, understand why the presentation thesis is neither entirely present nor entirely absent from Descartes’ theorizing in the Fourth Discourse by observing that gland’s contribution to visual sensory perception is not the primary topic of discussion. In section 3 I work through Descartes’ refinements of distance and size perception (among other things) to help show this. However, before doing so, I closely examine the wording in the French edition of the Optics in order to show that the “eyes in our brain” passage might be saying something slightly different than its standard translations reveal.

95 This modification, however, does alter our definition of “resemblance,” for I defined it as mere geometrical similarity, but it now appears to be a broader geometrical relation. Since it has little bearing on the topics at hand, though, I leave the issue aside. 96 I owe this point to Ott. See Ott 2017, 100. 95

Section 2

In its original French, the clause of interest is, “que ce soit par le moyen de cette ressemblance qu'elle fasse que les sentons” (AT VI 130). Olscamp translates it as meaning that one cannot “hold that it is by means of this resemblance that the picture causes us to perceive the objects,” and Cottingham-Stoothoff-Murdoch (CSM) translate is as saying that one cannot “think that it is by means of this resemblance that the picture causes our sensory perception of these objects.” The specific word I am interested in from this passage is the one translated as “perceived” by Olscamp and “sensory perception” by

CSM, translations derived from ‘sentons’, the first person plural indicative active of ‘sentir’.

The most literal English rendering of ‘sentir’ is “to feel” (Manchon 1951, 639), but it is clear that when Descartes uses the term in the Optics he means something roughly along the lines as CSM translates it, as “sensory perception.” It is especially important to emphasize

“sensory” here because I believe that Descartes uses ‘sentir’ often in the sense of sensations proper, that is, when talking about perceived secondary qualities. There are two textual considerations that help substantiate this claim, the first having to do with textual cohesion and the second with contrastive use.

Descartes begins the Fifth Discourse by writing (in French) that, “Vous voyez donc assez que, pour sentir, l'âme n'a pas besoin de contempler aucunes images qui soient semblables aux choses qu'elle sent” (AT VI 114; emphasis added). This passage is translated by Olscamp as “Thus you can clearly see that in order to perceive, the mind need not

96 contemplate any images resembling the things that make it sense” (O 91; emphasis added), and where Olscamp has “to perceive” CSM puts “have sensory perceptions” (CSM 1

166). But these translations, arguably, bring some confusion to the opening line of the

Fifth Discourse, in which Descartes takes himself to summarize the lessons of the Fourth

Discourse.

First, as we saw, the arguments of the Fourth Discourse do not in fact dismiss the general notion that minds attend to brain states and, moreover, Descartes even goes out of his way to remind readers that pineal images do resemble their objects to some degree.

Thus, at a general level, Descartes would be guilty of overcommitting were he to mean as strong a claim as standard translations have it. Second, and perhaps more pointedly, the final few of the Fourth Discourse do not appear to suggest such a sweeping claim either. For after wrapping up with the engraving analogy, Descartes immediately moves to say (using CSM this time):

Now we must think of the images formed in our brain in just the same way, and note that the problem is to know simply how they can enable the soul to have sensory perceptions [sentir] of all the various qualities of the objects to which they correspond—not to know how they can resemble these objects. For instance, when our blind man touches bodies with his stick, they certainly do not transmit anything to him except in so far as they cause his stick to move in different ways according to the different qualities in them, thus likewise setting in motion the nerves in his hand, and then the regions of his brain where these nerves originate. This is what occasions his soul to have sensory perception [sentir] of just as many different qualities in these bodies as there are differences in the movements caused by them in his brain (AT VI 113 - 114 / CSM 1 166 / O 90).

Nowhere in this passage is Descartes outright denying that resemblances in the brain are causes. Rather, he is saying that it is left to be explained how “they [images in the brain] can enable the soul to have sensory perception [sentir].” Descartes is keen to point out, then, that brain images do not account for “sensory perception” in virtue of resemblance,

97 but rather do so through the diverse “movements” within the brain (or, more particularly, movements of particles composing brain images). Thus, were one to read the opening of the Fifth Discourse as standardly translated, Descartes would appear to oversell his case once again. He would be denying that resemblances qua resemblances factor into visual perception, when he is merely entitled to the claim that resemblance are not the only type of physical cause. However, if one understands ‘sentir’ and its conjugates as referring to perceived secondary qualities, then the apparent textual infelicity disappears. Indeed, the

Fourth Discourse gives reason to “clearly see that in order sentir [referring to sensation proper], the mind need not contemplate any images resembling the things that make it sense (O 91),” since perceived secondary qualities are produced by motions alone.

The second reason for taking ‘sentir’ as a reference dedicated primarily to secondary quality perception comes from the very passage that seems to outright deny my reading: the “eyes in our brain” passage. Here is the whole passage in French, with two important emphases:

Or, encore que cette peinture, en passant ainsi jusqu'au dedans de notre tête, retienne toujours quelque chose de la ressemblance des objets dont elle procède, il ne se faut point toutefois persuader, ainsi que je vous ai déjà tantôt assez fait entendre, que ce soit par le moyen de cette ressemblance qu'elle fasse que nous les sentons, comme s'il y avait derechef d'autres yeux en notre cerveau, avec lesquels nous la pussions apercevoi (AT VI 130; emphases added).

In addition, here again is the Olscamp translation of the relevant part: “we must not hold that it is by means of this resemblance that the picture causes us to perceive [sentons] the objects, as if there were yet other eyes in our brain with which we could apprehend

[apercevoir] it.” Note Descartes’ shift from ‘sentir’ to ‘apercevoir’ in the clause. This shift is interesting because there is only a single place before the Sixth Discourse where

98

‘apercevoir’ or one of its conjugates shows up, but within the Sixth Discourse alone the term and its conjugates appears six times.97 I contend that this shift should not be understood as mere expressive variety.

Joseph Hwang has pointed out that Descartes’ use of ‘apercevoir’ and ‘sentir’ appears to track a Scholastic distinction in which the latter falls under the former, or as

Hwang states it, the two “are related with the one being a mode of the other” (Hwang 2011,

119). Indeed, Descartes does in fact seem to use ‘apercevoir’ in a way that aligns with perception generally considered rather than sensation proper. For, as I hope to make manifest in the next section, the broad goal of the Sixth Discourse is to provide mechanistic explanations of not just phenomenal qualities, but also one’s ability to make evaluations or judgments about those qualities. Thus, it makes sense to introduce a new term at the beginning of the Sixth Discourse, a term that refers more globally.

Moreover, Descartes does not drop ‘sentir’ from his lexicon in the Sixth Discourse, but continues to use it as what is best thought of as a reference to perceived secondary qualities. For example, late in the Sixth Discourse, Descartes discusses how intermediary surfaces affect one’s color attribution, conjecturing that, perhaps, someone looking at the white cloth of a camera obscura might mistakenly take the color of the object to which the image refers as, say, black when the object is in fact blue. Thus, using the Olscamp translation, Descartes writes,

Moreover, because we are accustomed to judge that the impressions which move our sight come from places toward which we must look in order to sense [sentir] them, when it happens that they come from some other place, we can easily be fooled; thus those whose eyes are infected by jaundice, or those who are looking

97 The word appears in the First Discourse when Descartes discusses the wine vat analogy, where he seems to have the most generic use of it in mind. See Chapter 1 for a discussion of the wine vat analogy. 99 through a yellow glass...attribute this color to all the bodies at which they look (AT VI 142 / CSM 1 173 / O 108 - 110).

As was the case in the previous discourses, ‘sentir’ is used here to point out secondary quality perception specifically rather than perception generally, suggesting, in turn, that

Descartes is sensitive to the distinction between perception broadly construed and sensation proper within the Sixth Discourse itself.

With this distinction in mind, then, what does Descartes mean when he writes that “we must not hold that it is by means of this resemblance that the picture causes us to sense [sentir] the objects, as if there were yet other eyes in our brain with which we could perceive [apercevoir] it?” He is getting at the fact that just as secondary quality perception does not depend on “looking at” resemblances, perception generally considered is not just a matter of minds inspecting some image or other, for perception— like sensation proper—also relies on non-resembling causes. Thus, the shift in vocabulary turns out to be a shift in topic, the topic now being those features of visual perception broadly considered and the non-resembling, physical causes that bring it about. Such causes are the focus of the next section.

Section 3

Descartes begins his discussion of visual perception broadly considered by listing

“six principal qualities,” writing that, “All the qualities that we perceive [apercevons] in the objects of sight can be reduced to six principal ones, which are: light, color, location,

100 distance, size, and shape” (AT VI 130 / CSM 1 167 / O 101). He then states that the first two—light and color—“alone belong properly to the sense of sight,” thus mirroring the

Scholastic distinction between proper and common sensibles, or the distinction between sensible qualities capable of being perceived by merely one sense modality and those capable of being perceived by more, respectively. In this section, I discuss how Descartes relates his mechanical theories to each of these qualities in order to show that none of the theories give clear evidence that Descartes rejects the presentation in the Sixth Discourse.

My reason for highlighting this feature of the Sixth Discourse is motivated by the fact that if Descartes meant to reject the presentation thesis here, then he would have provided a replacement for it. Thus, by showing that he does not provide a replacement—and that his mechanical theories are indeed consistent with the presentation thesis—I also hope to dismiss the notion that a central project of the Optics is to provide an account of body-to- mind interaction grounded merely in non-resembling physical causes.98 I begin by discussing the proper sensibles, as Descartes does.

Descartes lumps together his discussion of light and color, on the one hand, because both are proper to vision and, on the other hand, because motion physically causes the two. Descartes writes,

And first of all, regarding light and color, which alone properly belong to the sense of sight, it is necessary to think that the nature of our mind is such that the force of the movements in the areas of the brain where the small fibers of the optic nerves originate cause it to perceive light; and the character of these movements cause it to have the perception of color…yet in all this, there need be no resemblance between the ideas that the mind conceives and the movements which cause these ideas (AT VI 130 – 131 / CSM 1 167 / O 101).

98 It is fairly common to read the Optics as replacing the view of the Treatise. Schmaltz reads Descartes in this way, for example, writing that, “The concern throughout [the Optics] is to provide a replacement for the view that the mind senses objects by viewing resembling images of them in the brain” (Schmaltz 2007, 157). In addition, Simmons, citing the Fourth Discourse as evidence, writes that “Descartes presents the institution of Nature as a wholesale explanatory replacement for resemblance in the theory of perception” (Simmons 2003A, 557). 101

The physical causes of perceived light—what is more properly thought of as brightness—is the linear speed or “force” of particles emitted from the pineal gland, while the physical cause of perceived color is the spin or “character” attached to those particles, and both types of causes have been “established by nature” to produce the relevant phenomenal characteristics.99 As a note on vocabulary, Descartes often talks about causes “established by nature” and the like, and this manner of speech has lead commentators to read

Descartes as committed to a “natural institution model” of causation. Broadly understood, this terminology refers to non-resembling causation, the type of causation captured in the notions of direct causation and occasionalist causation discussed in the previous chapter

(although it does not, in and of itself, disqualify the presentation thesis). I use the term according to this broad rendering.

Now, for the purposes here, the question is whether or not there is evidence for reading Descartes as claiming that the sensory perception produced by spin is a phenomenal experience of color plus extension. If he does claim this, then the presentation thesis of the Treatise has been replaced by a theory of body-to-mind interaction merely positing non-resembling causes, an interpretation that some find persuasive.100 At first pass, the clarifications Descartes provides when articulating the physiology relevant to perceived color might push one toward this replacement reading.

For example, Descartes says,

You will readily believe this if you note that it seems to those who receive some injury in the eye that they see an infinity of fireworks and lightning flashes before them, even though they shut their eyes or else are in a very

99 The physical cause of color perception is introduced in the First Discourse, where Descartes likens the production of particle spin or “character” to tennis players grazing a ball. And so, presumably, there are as many perceivable colors as there are possible manners of spin. See AT VI 90 / O 73 [the relevant portion is removed in CSM]. 100 This appears to be how Simmons’ understands the significance of Descartes’ comments on color in the Sixth Discourse. For example, see claims that “sensations of colors, as Descartes describes them, are sensations of color patches, not sensations of color points” Simmons 2003, 557. I say more about Simmons’ thought on this issue in the next section. 102 dark place…And this is also confirmed by the fact that if you sometimes force your eyes to look at the sun, or some other very strong light, they retain its impression for a short time afterwards, in such a manner that, even if you keep them shut, you seem to see various colors which change and pass from one to the other as they grow weaker (AT VI 131 / CSM 1 167 – 168 / O 101 – 102).

Simple reflection upon one’s own sensory experience shows that the “fireworks and lightning flashes” or the “various colors” appealed to in these examples are perceived as simultaneously extended, and so one might think the production of perceived color brings along perceived shape. Nonetheless, there is plenty room to doubt that Descartes means to say here that particle spin yields these two phenomenal qualities conjointly.

First, note that Descartes carefully identifies specific motions of particles as those responsible for producing perceived color and light, namely the spin and force, respectively. However, nowhere in the physiological details relevant to color and light perception does one find a physiological process that correlates with perceived shape— there is no explanation of how spin or force concomitantly produces perceived shape alongside perceived color and light, respectively. The mere fact, then, that the example appeals to extended color patches is not enough to show that Descartes intends his physiological account of color to explain perceived shape as well. The oblique reference to perceived shape is a mere artifact of the example—not what is being clarified by it.

Second, Descartes knowingly follows the Scholastic distinction between common and proper sensibles, and takes care to list color under the latter. However, shape is a common sensible (since it can be determined by sight and touch), and so it would be strange for him to include visual shape perception in a passage that is explicitly devoted to proper sensibles. Which leads us to yet another consideration, namely, that shape is listed individually among the six principal qualities, and so, if a replacement has occurred, one

103 would expect some overlap in the physiological mechanisms relevant to perceived color and perceived shape. However, as I show shortly, there is no overlap. There thus seems little substantial evidence suggesting that perceived shape comes out of particle spin.

Now, as we just saw, in his discussion of the two proper sensibles Descartes appeals to the institution of nature. His account of the remaining four principal qualities keeps in theme, often appealing to natural institution, but now adds one critical component. In addition to the physiological details (of which there are many), Descartes adds actions of the mind to the story. These actions are not of robust kind, however, since minds do not engage in them at a conscious, transparent level. They are rather actions of which one is largely unaware, being more or less automatic mental responses to physical going-ons in the brain. Descartes thus invokes a dual-effort process—one involving mind and body—when explaining the remaining four perceived qualities, the common sensibles.

However, the rendering of common sensibles in the Sixth Discourse are not what one would normally think of as phenomenal characteristics, those perceptual features like phenomenal color or phenomenal shape. Instead, the perceptual features that Descartes addresses when talking about location, distance, size, and shape are evaluative or recognitional in kind (as opposed to phenomenal in kind). They are subconscious but nonetheless fully intellectual evaluative acts. For this reason, Descartes often expresses his points in the remainder of the Sixth Discourse by using words like ‘knowledge’

(‘connaissance’), ‘judge’ (‘juger’), or ‘opinion’ (‘opinion’).101 This is among the central

101 Both Wolf-Devine and Ott see Descartes as obfuscating his meaning by switching to this terminology in the Sixth Discourse. I think this can only be the case if one reads him as giving an account of mere phenomenal awareness, a claim with which I disagree. See Wolf-Devine 1993, 73, and Ott 2017, 109 - 110. 104 reasons I argue that the Optics does not aim to dethrone the presentation thesis. For, as I read it, Descartes’ comments on the common sensibles are not meant to account for the production of any phenomenal characteristics whatsoever, and thus his remarks on them cannot but fail to replace the presentation thesis. In order to establish this important claim, let’s now move to Descartes’ comments on position.

Regarding position, Descartes writes,

As to position, that is to say the direction in which each part of the object lies with respect to our body, we perceive [nous ne l'apercevons] this with our eyes in the same way as we would with our hands; and this knowledge [connaissance] does not depend on any image, nor on any action which proceeds from the object, but only on the position of the small points of the brain whence the nerves originate (AT VI 134 / CSM 1 169 / O 104).

Descartes posits naturally instituted correlations between brain states and mental states, as he did with color and light. He claims that the locations of optical nerve endings relative to one another determine one’s awareness of bodily position relative to surrounding objects. Thus, Descartes wants readers to recognize that specifying spatial location is just a matter of the mind interpreting the relative location of nerve endings.

This is why Descartes later adds an appeal to the “blind man of whom we have already spoken” about in the First Discourse, for blind men can figure out their location despite an inability to visually perceive any image whatsoever.102 And the reason he says that this

“knowledge” does not require an image has nothing to do with the presentation thesis.

Minds may very well “look at” the brain yet merely rely on entirely distinct physiological features to evaluate bodily spatial location.

102 See AT VI 135 / CSM 1 169 / O 104 - 105. As an additional note, if one is to understand the blind man analogy in its full import, then it has to be assumed that the mechanisms related to tactile sensation inform nerve endings in the brain in the same way that these nerve endings are informed by light particles. 105

Distance perception is next on the list, and Descartes claims that there are three distinct physiological accounts of it.103 The first is a follows:

The seeing [vision] of distance depends on no more than does the seeing of location upon any images emitted from objects; but in the first place upon the shape of the body of the eye. For as we have said, for us to see that which is close to our eyes, to see what is farther away, this shape has to be slightly different. And as we change it in order to adjust the eye to the distance of objects, we also change a certain part of our brain, in a way established by nature to allow our mind to perceive [apercevoir] that distance (AT VI 137 / CSM 1 170 / O 105 – 106).

There is a depth to this passage that will come to be of significance in the next section, and so I alert readers to certain features now in order to motivate what I claim later.

Accordingly, in the account here Descartes appears to reference two distinct processes, one responsible for the phenomenal characteristic of distance and another for the judgment or evaluation of distance.

The process that Descartes references as occurring “in the first place” is that of squinting, which one naturally does to help something appear closer or father away.

Descartes explains the physiology relevant to squinting in the Third Discourse by invoking the liquid humor located between the pupil and the eye’s external surface. He describes this humor “to be like a small muscle which can contract and enlarge as we look at objects that are nearer and farther, or more or less lighted, or else when we wish to see them more or less distinctly” (AT VI 107 / O 85).104 But the Treatise describes the humor more suggestively, for there Descartes writes,

The change of shape that occurs in the crystalline humour allows objects lying at different distances to paint their images distinctly on the back of the eye…So that in order to represent point x distinctly, the whole shape of humour LN has to be changed and become slightly flatter, like that marked I; and to represent point T it has to become slightly more arched, like that marked F (AT XI 155 – 156 / G 128).105

103 The tenor of Descartes’ comments on distance perception suggests that these three processes are independently sufficient but not jointly necessary. 104 The Thirds Discourse is absent in CSM. 105 The relevant passage is abridged from CSM. 106

Without laboring over the illustration to which Descartes appeals, his general point is that the crystalline humors must either flatten or expand in order to make one part of the retinal image “represent” something as closer or farther. This an important phrasing to note because, if read plainly, Descartes suggests that retinal images themselves capture the appearance of something as further or nearer; that is, Descartes appears to claim that, in virtue of the humor’s shape, perceived distance is rendered within the retinal image and, so, within the pineal image as well. This is worth keeping in mind for later.

Moving on, as the passage from the Sixth Discourse indicates, squinting produces some consequent “change [in] a certain part of our brain” that, in turn, is “established by nature to allow our mind to perceive [apercevoir] that distance.” Thus, the passage is not claiming that squinting alone causes one to perceive distance (in the sense of

“apercevoir”). It is rather some (unspecified) physiological effect of squinting conveyed to the brain by the optical nerves that, in turn, signals the mind to judge accordingly. And the type of perception related to this change “in a certain part of brain” is one of intellectual evaluation, as is made clear in Descartes’ second account of distance perception.

The second account can be thought of as mental triangulation, and Descartes again appeals to the blind man to elaborate. Just as the blind man estimates the point at which two guiding sticks intersect by evaluating the relative distance between his two hands and the angles at which he holds the stick, a sighted person too evaluates something’s distance “as if by natural geometry.” According to Descartes, the subconscious mind of a sighted person judges the distance between their eyes relative to the observational angles at which an object stands in relation to them. Descartes likens 107 the judgment to the efforts of a land-surveying team, saying that it “...happens by an action of thought which, although it is only a simple act of imagination, nevertheless implicitly contains a reasoning quite similar to that used by surveyors, when, by means of two different stations, they measure inaccessible places” (AT VI 138 / CSM 1 1 170 / O

106).106 When stripped of all the physiological details, the central claim here is simply that minds calculate distance in virtue of certain physiological features, a claim quite removed from the presentation thesis’ concerns.

Descartes summarizes his third account of distance perception by stating that “We have yet another way of perceiving distance, which is through the distinctness or indistinctness of the shape seen, together with the strength or weakness of the light” (AT

VI 138 / CSM 1 170 / O 106), and articulates it as follows:

And, looking at a mountain exposed to the sun beyond a forest covered with shade, it is only the position of this forest which makes us judge [juger] it the nearer; and looking at two ships on the sea, one of which is smaller than the other but proportionality closer, so that they appear equal in size, we will be able to judge [juger] which is farther away by the difference in their shapes and colors and in the light which they send toward us (AT VI 140 / CSM 1 172 / O107). 107

Based on the positions, locations, and shapes of phenomenal characteristics, one’s mind approximates an object’s distance. And lest one be persuaded by the appeal to perceived shape into thinking that Descartes is explaining how phenomenal shape is produced, it just need be reminded that this puts the cart before the horse. For the account here presupposes perceived shape, and so, were Descartes meaning to explain how perceived shape comes about, he would be reasoning in a circle.

106 The “act of imagination” that Descartes refers to is that of imagining lines extending from the eye to the relevant object. See AT VI 137 – 138 / CSM 1 170 / O 106. Moreover, one might demand of Descartes here an account of how the mind knows the distance between the eyes. Although Descartes does not provide an answer, one could easily imagine him responding in a way that appeals to the determination of distance, namely by claiming that the movement of the optic nerves informs the mind of the relevant distance. 107 In explaining the physiological details, Descartes repeats his account of light transmission and perceived brightness. See AT VI 138 – 140/ CSM 1 170 – 172 / O 106. 108

The final two common sensibles are treated together in a relatively brief paragraph because Descartes understands them as parasitic on distance and position perception.

Nonetheless, I separate the two since Descartes’ comments on shape perception, at least as a topic, has the most relevance to defending the presentation thesis. Accordingly, about size perception, Descartes writes,

As to the manner in which we see [nous voyons] the size and shape of objects, I need not say anything in particular, inasmuch as it is all included in the manner in which we see the distance and the position of their parts. Thus, their size is estimated [estime] according to the knowledge [connaissance], or the opinion [opinion], that we have of their distance, compared with the size of the images that they imprint on the back of the eye; and not absolutely by the size of these images, as is obvious enough from this: while the images may be, for example, one hundred times larger when the objects are quite close to us than when they are ten times farther away, they do not make us see [voir] the objects as one hundred times larger because of this, but as almost equal in size, at least if their distance does not deceive us (AT VI 140 / CSM 1 172 / O 107).

Descartes draws readers’ attention to the fact that retinal images and their analogues are not all there is to size determination. In order to determine relative size, it is not as if one merely looks down upon the pineal image that has, mutatis mutandis, been transferred from the retinas. Were that all one does, then there would be no way of explaining about size constancy of faraway objects. So, as Descartes explains, something more is going on, something that requires a knowledge of distance “compared” with retinal images.

But what precisely this “comparison” amounts to is mysterious, at least if the presentation thesis is pushed aside.108 For if size estimation is just a matter of the mind decoding non-resembling brain messages, it is difficult to understand why Descartes is talking about retinal images in the first place. The above passage obviously suggests that retinal images play some part in one’s reckoning of size, but if Descartes means to replace the presentation thesis with mere non-resembling causes, then retinal images qua

108 Ronald Arbini notes this difficulty, although he does not resolve it in the way I do. He denies the presentation thesis, and so understands the pineal image as a mere “theoretical posit.” See Arbini 1983, 326 – 328. 109 resemblances cannot have a part. So the best way to read Descartes here, by my lights, is to see him as presupposing the presentation thesis. He is claiming that shapes impressed on retinal images—and consequently shapes impressed on the gland—do not alone explain estimations of size. Evaluating size requires an unconscious recognition of distance in addition to one’s direct inspection of the pineal image. I believe the same sort of story applies to his comment on shape perception as well.

On shape perception, Descartes writes,

And it is also obvious that shape is judged [se juge] by the knowledge [connaissance], or opinion [opinion], that we have on the position of various parts of the objects, and not by the resemblance of the pictures in the eye; for these pictures usually contain only ovals and diamond shapes, yet they cause us to see [voir] circles and squares (AT VI 140 / CSM 1 172 / O 107).

In saying that retinal images “contain only ovals and diamond shapes” although they

“cause us to see circles and squares,” Descartes makes direct reference to the engraving analogy, in which he claimed that retinal and pineal images are perspectival renderings.

Descartes thus points out that the retinal and pineal images cannot entirely account for judgments of shape since they are just images of how objects appear from such-and-such vantage. Thus, to correct one’s understanding of what appearances present (if needed), minds apply knowledge about the relative positions of an image’s parts (i.e. the relative distance of the image’s boundaries), and thereby cause one to realize that, say, an elliptical impression represents an object that is actually circular.

The Sixth Discourse does not end with comments on shape perception, however.

After wrapping up the discussion about the six principal qualities, Descartes hopes to further persuade readers of his conclusions by considering how visual perception

“occasionally deceives us.” The dialectical purpose, I take it, is to give more evidence for

110 believing that visual perception generally understood (in the sense of ‘apercevoir’) is not simply a matter of resembling causes. In pursuit of this end, Descartes includes more physiological hypotheses, often times accompanying them with diagrams of similar complexity to those we examined previously. I do not think it necessary to engage these explanations at length or with the diagrams at all, however, because what I want to note about the remaining passages has only to do with the fact that the explanations continue to treat corporeal images—both on the retinas and the gland—as pertinent to the explanations at hand, and the central theme again appears to be that corporeal images cannot explain everything (although they do explain some things).

Descartes begins his comments on the “occasional” deceptions of visual perception by writing, “First, it is the soul which sees, and not the eye; and it does not see directly, but only by means of the brain” (AT VI 141 / CSM 1 172 / O 108; note: this is the CSM translation). This passage, of course, fails to choose sides, seeing as it fits with either my reading or those against it. But when Descartes then moves to talk about mistaken judgements about position, he thinks it relevant to bring up the pineal gland, writing that,

“Also, because the impressions which come from without pass to the common sense by way of the nerves, if the position of these nerves is constrained by some extraordinary cause, it can make us see objects in places other than where they are” (AT VI 141 / CSM 1

172 - 173 / O 108). Sudden anomalies in the ocular nerves can interrupt and shake up, as it were, an image passing from the eyes to the pineal gland in such a way that causes aberrations in positional encoding. Thus, as with his accounts of perceived size and shape, images appear relevant to the overall account, for the claim simply seems to be that

111 the perceived position of what is represented on the pineal gland is consequent upon features of the ocular nerves.109

Descartes continues to assign importance to images impressed on the gland when discussing misjudgments about the comparative sizes of the sun and moon. In what appears as a lapse into his earlier practice of calling corporeal images “ideas,” Descartes writes that,

As a consequence, even our ‘common sense’ seems incapable of receiving itself the idea of a distance greater than approximately one or two hundred feet. This can be verified in the case of the moon and the sun. Although they are among the most distant bodies that we can see, and their diameters are to their distances roughly as one to a hundred, they normally appear to us at most only one or two feet in diameter—although we know very well by reason that they are extremely large and extremely far away (AT VI 144 / CSM 1 173 / O 110 - 111; note: this is the CSM translation).

There is little room to doubt that Descartes is speaking directly about images impressed upon the gland in this passage, the key claim being that impressions of objects at astronomical distances fail to contain adequate information about their relative sizes.

The final set of visual deceptions that Descartes showcases in the Sixth Discourse are mistaken judgments about the sizes of extremely bright objects. As Descartes clearly states, impressed images play a part in misperceptions here too, “And the reason why these white or luminous bodies appear larger consists not only in the fact that the estimate we make of their size depends on that of their distance, but also on the fact that they impress bigger images on the back of the eye” (AT VI 145 – 146 / CSM 1 174 / O 112).

Brighter objects appear larger due to imagistic glitches in the retinal image (in a manner of speaking), and such glitches carry over to the pineal gland.

109 It is worth noting that the passage cited in the previous section in which Descartes comments on the effects of intermediary surfaces on color attribution comes from this section of the Sixth Discourse and that there, as well, he seems to assign a role to imagistic impressions. I leave it out of the main text for the sake of brevity. 112

I highlight these explanations in the final parts of the Sixth Discourse in order to show that Descartes still takes corporeal images—and therefore resembling causes—as a central component of visual perception. Of course, this fact alone does not mean that the presentation thesis is part of the Optics’ official view. Nonetheless, when put in light of the fact that the Sixth Discourse and the Optics in general lack any detail about the physiological causes of perceived shape, the significance that Descartes gives to corporeal images in the Sixth Discourse goes a long way toward motivating the conclusion that the presentation thesis is somewhere in the background. It also shows that reading Descartes as replacing the thesis with a purely non-resembling causal story misses the mark. On the one hand, such a reading presupposes an account of perceived shape when the text in fact offers none (e.g. in Descartes’ physiology of perceived color). On the other hand, these readings also make the mistake of confusing a physiology of evaluative capacities for a physiology of the phenomenological.

As a final note, although I contend that the presentation thesis is not denied in the

Optics, this certainly is not grounds for believing that it is endorsed in the work. Why, then, is Descartes not forthright about his commitments? Questions such as this cannot help but be speculative. However, I do agree with Ott that, in a certain respect,

“Descartes’ views are very much in flux in this middle period” (Ott 2017, 111). But I do not think the transitions have to do with swapping out the presentation thesis for a mere natural institution model. They rather have to do with Descartes confronting the varied characteristics of visual perception. For he seems to have realized the limitations of the presentation thesis, and therefore endeavored to explain the precise roles of non- resembling causes in the production of visual perception more broadly. He indeed 113 overemphasized this goal in the Optics, but, as I hope to have demonstrated, his overemphasis does not amount to a denial of the presentation thesis. The story of visual perception is not completed in the Optics, though. Descartes has one more piece to add, and it comes during the era of the Meditations.

Section 4

In the Sixth Replies, Descartes responds to an unknown objector’s worry about the

First Meditation’s claim that “…we ought to mistrust the operations of the senses and that the reliability of the intellect is much greater than that of the senses” (AT VII 418 / CSM 2

282 – 283). The reply has received attention in contemporary literature in large part because it is thought to heavily modify Descartes’ view of sensory perception. In what follows I argue that although Descartes’ view does undergo some changes in the Sixth

Replies, these changes are not as dramatic as some commentators contend. In particular, I argue that the change is but a slight addition to the roles that Descartes assigns to the intellect in the Sixth Discourse of the Optics. To see why, let’s now turn attention to the three grades of sensation introduced by Descartes in the Sixth Replies, examining each in turn to determine whether or not they pose problems for my reading.

Descartes describes the first grade in this way: “The first is limited to the immediate stimulation of the bodily organs by external objects; this can consist in nothing but the motion of the particles of the organs, and any change of shape and position resulting from this motion” (AT VII 436 / CSM 2 294). At first pass, the first grade might

114 seem limited to things physically interacting with one’s sensory organs, thus seeming to only include things such as directional configurations and fire particles. But one should add the straddling mode to list as well, for the first grade also includes “any change of shape and position resulting from this motion.” What, then, are we to make of this fact?

A straddling mode cannot, in and of itself, belong to the first grade because it is not fully material (if material at all). But, keeping in mind that figures on the pineal gland’s surface directly produce impressions within a straddling mode’s surface, the straddling mode can be thought to fall among the first grade in a particular sense. For a change on the straddling mode’s surface is a “change of shape” brought about by changes in the sensory organs. Yet more interesting, when considered as the direct intentional object, the surface of a straddling mode still falls among the first grade, for the causal agent by which the intentional relation occurs is shape, and the straddling mode’s shape is a direct result of the sensory organs interacting with the external world. Nonetheless, it should be remembered that this classification does not adequately capture the unique ontological status of straddling modes since the classification cannot amount to more than helpful ways of speaking.

Descartes thinks of the second grade as follows,

The second grade comprises all the immediate effects produced in the mind as a result of its being united with a bodily organ which is affected in this way. Such effects include the perceptions of pain, pleasure, thirst, hunger, colours, sound, taste, smell, heat, cold and the like, which arise from the union and as it were intermingling of mind and body, as explained in the Sixth Meditation (AT VII 437 / CSM 2 294).

Descartes is obviously assigning phenomenal characteristics to the second grade, and as his list indicates, he is thinking specifically about perceived secondary qualities.110 In the

110 The fact that Descartes references the Sixth Meditation here is interesting. For, as I noted in Chapter 2, the Sixth 115 previous chapter I argued that perceived color—the most relevant of the bunch—is one of two concomitant effects produced by the action of a straddling mode, although it is not a figure per se that produces perceived color, but rather the motions of particles constituting a figure. Moreover, I claimed that figures on the gland—in virtue of motion—appear as colored. Thus, when considered as the mind’s aspect of a straddling mode, perceived color is decidedly mental.

It is worth pausing at this juncture to consider a competing reading. According to my view, the intentional object of perceived shape falls within the first grade, an interpretation that is as rare as those who endorse the presentation thesis. In contrast to my reading, though, Simmons influentially argues that the intentional object of perceived shape belongs to the second grade. She writes that “Second grade sensations of color, as

Descartes describes them, are sensations of color patches, not sensations of color points”

(Simmons 2003A, 557), and rather pointedly concludes that “In sum, both primary and secondary qualities are represented to some extent at the purely sensory second grade of sensory perception” (Simmons 2003A, 563).111 The bulk of Simmons’ evidence for this claim comes not from the Sixth Replies, but from the Treatise and the Optics, and I quickly address these before moving on to the third grade.

Accordingly, Simmons appeals to Descartes’ claim from the Treatise that stimulation of the pineal gland “can give the soul occasion to sense movement, size, distance, colours, sounds, smells, and other such qualities; and even makes it sense

Meditation seems only to speculate on the physical causes of perceived secondary qualities, and Descartes here in the Sixth Replies appears to knowingly keep this restriction in mind. This thus acts as additional evidence that Descartes’ discussion of non-resembling causes in the Meditations is meant to only account for perceived secondary qualities. 111 Hatfield and Epstein also understand the second grade as having spatial content, and like Simmons they pull much of their evidence from the Treatise and Optics. I focus exclusively on Simmons’ reading, however, because her comments fit better with the concerns here. See Hatfield and Epstein 1979, 374 - 378. 116 pleasure, pain, hunger, thirst, joy, sadness, and other such passions” (AT XI 176 / CSM 1

106 / G 149).112 The fact that Descartes lumps primary and secondary qualities together in this passage indicates, for Simmons, that perception of both types of qualities derives solely from the institution of nature, thereby putting the intentional object of perceived shape in the mind. But as we can gather from Chapter 2, this passage ought not to be read alone, since Descartes shortly thereafter goes on to make one of the clearest avowals of the presentation thesis, stating that the soul “will directly consider” figures on the gland. Moreover, from the Optics Simmons refers to the Sixth Discourse, emphasizing the

“eyes in our brain” passage and other passages from Descartes’s comments on distance perception.113 But my view on such passages should be fresh in mind: the Optics gives us no clear commitments on the production and intentionality of perceived shape. Thus, appealing to it does not help locating the intentional object, whether it be in the mind or the body.

Returning now to the three grades, the interpretive debate surrounding the Sixth

Replies’ account of sensory perception revolves around what Descartes means to be doing with the third grade. Fortunately, Walter Ott identifies the two main points of debate,

We can isolate two areas of controversy. First, there is a debate over just how, and in what sense, the third grade is intellectual: some commentators take it to be a matter of a priori reasoning, or of the deployment of the innate idea of extension, or the development of justified beliefs. Second, there is the question of where to put the mind’s awareness of geometrical properties: is it confined to the third grade, or is it already present at the second (Ott 2017, 115)? 114

112 See Simmons 2003A, 557. 113 See Simmons 2003A, 556 – 559. 114 In regards to the first debate, Ott attributes these views, in order of appearance, to: Maull 1978; Secada 2000, 132; and Atherton 1990, 30. He also notes his indebtedness to Simmons’ classification of these readings in Simmons 2003A, 555, a classification to which I am also indebted. See Ott 2017, 115 fn 6. 117

As one can surmise, I engage in the latter debate, for I just argued that, contra Simmons and others, the intentional object of perceived shape does not belong to the second grade and, moreover, I committed my view to locating it in the first grade (a view which Ott ignores because he holds a replacement reading of the Optics). I thus now move to argue that the object of which one is immediately aware when perceiving shape does not belong to the third grade either.

Here, then, is how Descartes introduces the third grade: “The third grade includes all the judgments [judicia] about things outside us which we have been accustomed to make from our earliest years—judgments which are occasioned by the movements of these bodily organs” (AT VII 437 / CSM 2 295). At first pass, this definition seems fairly innocent, seeming little more than a gesture towards his conclusions from the Sixth

Discourse, particularly in light of the fact that Descartes uses the Latin ‘judicium’. But, of course, there would be little debate if this were all he had to say.

The debate sparks from the way in which he tries to distinguish the grades from one another. Descartes starts his explanation with a description of how, at certain times, the intellect provides a better guide to the physical world than sensory experience. He writes,

For example, when I see a stick, it should not be supposed that certain ‘intentional forms’ fly off the stick towards the eye, but simply that rays of light are reflected off the stick and set up certain movements in the optic nerve and, via the optic nerve, in the brain as I have explained at some length in the Optics. This movement in the brain, which is common to us and the brutes, is the first grade of sensory response. This leads to the second grade, which extends to the mere [ad solum] perception [perceptionem] of color and light reflected from the stick; it arises from the fact that the mind is so intimately conjoined with the body that it is affected by the movements which occur in it. Nothing more than this should be referred to the sensory faculty, if we wish to distinguish it from the intellect (AT VII 437 / CSM 2 295).

Descartes’ claim that the second grade does not extend beyond the “mere perception of color and light” is an important point for the purposes here. First, Descartes appears to 118 understand himself here (as he will later) as merely rehearsing the lessons of the Optics, implying that the physiology of color in the Sixth Discourse is meant to account for this

“mere perception” as well. We see him, then, acknowledging more explicitly in the Sixth

Replies what was but a buried implication in the Optics: considered in and of itself, the causal process of perceived color does not bring perceived shape along with it. Second, this talk of “mere perception” counts as yet another reason against locating the object of perceived shape in the second grade, and so what one’s aware of when perceiving shape should either be bumped down to the first grade or moved up to the third.

Descartes continues by writing,

But suppose that, as a result of being affected by this sensation of color, I judge that a stick, located outside me, is coloured; and suppose that on the basis of the extension of the colour and its boundaries together with its position in relation to the parts of the brain, I make a rational calculation about the size, shape, and distance of the stick: although such reasoning is commonly assigned to the senses (which is why I have here referred it to the third grade of sensory response), it is clear that it depends solely on the intellect. I demonstrated in the Optics how size, distance and shape can be perceived by reasoning alone, which works out any one feature from the other features (AT VII 437 – 438 / CSM 2 295).

This passage vexes many a commentator, and does so largely in virtue of three seemingly problematic claims. First, despite saying right beforehand that second grade sensations are merely perceived secondary qualities, it seems that perceived extension (of color) now belongs to the second grade as well, suggesting to some commentators that Descartes was misleading in what he wrote just a few sentences prior.115 Second, Descartes claims that the boundaries of perceived extension have some sort of positional “relation to the parts of the brain,” an obvious reference to like the presentation thesis that has given other interpreters reason to take Descartes as being careless again.116 Finally, Descartes writes that it is “on the basis” of these two features—perceived extension and its “relation”

115 See Simmons 2003A, 556. 116 See Hatfield 1992, 354. 119 to the brain—that some “rational calculation about size, shape, and distance” is made, leaving yet another commentator to view Descartes as committed to an internal and intractable philosophical problem.117 But none of this has to be attributed to Descartes if the presentation thesis is an option.

The two allegations that Descartes misspoke are simply artifacts of believing that the presentation thesis is a thing of the past. Regarding the first, Descartes’ claim that second grade sensations are merely secondary qualities need not be passed over in light of what he writes about the “extension of color” because, according to my reading, the extension of perceived color in fact does not belong to the second grade—it belongs to the first. Moreover, one need not think of Descartes’ talk about the “relation” between perceived extension and “parts of the brain” as a brief lapse into youthful theorizing since,

I maintain, the presentation thesis is a background assumption in this period of writing.

According to my reading, then, the “relation” between the extension of perceived color and “parts of the brain” to which Descartes gestures is a feature of a straddling mode.

Indeed, as an additional point worth considering, one should not be surprised to see the presentation thesis at work here in the Sixth Replies since Descartes forthrightly appeals to the thesis in both the Second Replies and Fifth Replies.118 Finally, and importantly, some corroboration for the idea that the presentation thesis is presumed in the Optics as well is garnered from this passage. For, as Descartes claims in the passage, he is merely recounting what he has already “demonstrated in the Optics,” and in this passage the presentation thesis indeed seems presumed.

117 See Ott 2017, 121. 118 See Chapter 2. 120

Thus, so far, there are some good reasons for believing that, here in the Sixth

Replies, Descartes is committed to putting the object of perceived shape among first grade sensations. However, the evidence has been largely gathered from what he says about second grade sensations. I thus now move to arguing that additional evidence can be found within his remarks on the third grade, and I produce this evidence by showing how the presentation thesis along with the straddling modes interpretation helps remove an apparent problem in the Sixth Replies’ account of sensory perception.

The problem is raised by Ott, and some background assumptions need be recognized in order to understand its force. First, Ott believes that second grade sensations are just perceived secondary qualities, which is grounded in the text, as we saw earlier. This means, then, that the extension of perceived color is not an artifact of the second grade. But, for Ott, this extension is not attributable to the first grade either because he reads Descartes as abandoning (or at least as extremely doubtful about) any notion of directly inspecting the brain.

Accordingly, for Ott there is no other place from which to generate perceived extension than the third grade. Ott’s construal of the third grade thus involves a process in which, “we as it were paint a region of the mind-independent extension with colors,” a procedure that he likens to “throwing a sheet over an invisible couch: by using something foreign to the object, one is able to determine its outline” (Ott 2017, 118). And such a reading, I believe, is where one ought to land if one endorses a replacement reading of the

Optics and then takes Descartes at his word in the Sixth Replies. But it is not quite where one wants to be, for minds cannot help but stumble about when trying to find the

“invisible couch.” Speaking more directly about this concern, Ott writes, 121

The sensations [at the second grade] on their own are not sensations of anything; they need to be projected in judgment. But what guidance is there for this projection [at the third grade]? It’s not enough for the mind to judge that something is outside of me is causing this sensation. The mind has to judge that this thing, which begins here and ends there, is responsible for the sensation. To see what makes the problem intractable, given Descartes’s set-up, consider the following dilemma: do we have awareness of the region of extension that constitutes the stick independently of our awareness of color, or not? If we do, then color is otiose: we would be able simply to judge that there is a determinate region of extension we’re calling ‘the stick’ without undergoing any sensations. Clearly, that is not Descartes’s view. But if our only visual awareness of extension comes through color, then there is nothing to guide us when it comes to judge where to apply it. Being told to paint-by- is an intelligible command only if there are outlines within which we are supposed to apply the colors (Ott 2017, 121).

This is an illuminating dilemma that goes to show how one’s view of Descartes’ theory of sensory perception as a whole affects one’s reading of the Sixth Replies.

On the first horn of the dilemma (which is Ott’s second horn), if one buys into the standard replacment reading of the Optics in conjunction with sticking to the letter of

Sixth Replies, then one is left with the stumbling minds’ ordeal, for, on such a reading, minds lack any sort of navigational tools to help discover the requisite shape. But, as one might rightly suspect, the presentation thesis aids in avoiding this debacle, for accepting the presentation thesis avoids assigning a projective function to minds. On the reading I offer, perceived color comes prepackaged with perceived extension. Nonetheless, the presentation thesis alone does not immediately dismiss the other horn of Ott’s dilemma.

If one wants to circumvent the stumbling minds problem by locating the object of perceived extension in the bodily realm—and therefore in the first grade—then perceived color comes across as a theoretical excess. One’s judgment that such-and-such bit of extension is of such-and-such shape could, so to speak, reach right out to the physical world, bypassing any need for perceived color, a curious problem indeed for the presentation thesis considered in isolation. But this is where straddling modes come in handy. According to my understanding of body-to-mind interaction, images on the pineal gland are not seen as they are in and of themselves. They are instead seen as colored, and 122 inextricably so because perceived color is a byproduct of attending to pineal images, a byproduct produced by motion. Thus, according to my reading, one’s judgments of shape cannot reach out to the invisible world of bodies due to the very ontological composition of the mind-body interaction; it is simply a brute fact that the mind’s surface appears as colored.

Thus, in the end, if perceived shape belongs to the third grade (and one sticks to the letter of the text), then Ott is correct: there is a big problem. Perceived shape, then, should not be attributed to the third grade or the second grade either. It should be put in the first grade, the most worry free of the three.

In all this, however, I have yet to say what actually happens at the third grade of sensation. My answer: nothing new. Descartes, as he claims, really is just repeating the lessons of the Optics, but emphasizing here that evaluations of distance, size, shape, and so on, require mental actions in response to mechanical going-ons in the brain. Descartes introduced the three grades in order to explain to his critics why “the reliability of the intellect is much greater than that of senses.” To this end, he develops the three grades, I contend, not to modify the theory of the Optics, but to remind readers of the fact that one is not a mere machine. One is rather a body-soul composite capable of determining whether or not sensory information rightly reflects the world. The bent-stick example is then but an innocuous one, alerting readers to the fact that sometimes sensory input does not get things quite right. Nonetheless, something novel is found within Descartes’ three grades, but it is not a claim about the production of phenomenal sensory experience. It is a claim about the growth of reflective capacities.

After wrapping up his explanation of the three grades, Descartes writes, 123

It is clear from this that when we say ‘The reliability of the intellect is much greater than that of the senses’, this means merely that when we are grown up the judgments which we make as a result of various new are more reliable than those which we formed without any reflection in our early childhood; and this is undoubtedly true. It is clear that we are not dealing with the first and second grades of sensory response, because no falsity can occur in them. Hence when people say that a stick in water ‘appears bent because of refraction’, this is the same as saying that it appears to us in a way which would lead a child to judge that it was bent—and which may even lead us to the same judgments, following the preconceived opinions which we have become accustomed to accept from our earliest years (AT VII 438 / CSM 2 295 - 296).

Experience deepens one’s ability to reflect upon the raw data of sensory experience, allowing one to incorporate past judgments as one grows older so as to correct potentially deceptive appearances. The of this capacity is what Descartes rightly adds to his theory of the Optics, for there he treated evaluative capacities in abstract, only but hinting at the contingent capacity for reflective growth (in his concluding discussions on visual deceptions). So, in the end, the “reliability” that Descartes addresses is not one about the causal processes leading up to sensory phenomenal experiences, but instead one about the ability to discern the truth or falsity of sensory content delivered to the mind by these very processes.

Overall, the Sixth Replies does not appear to conflict with the Optics or the presentation thesis if one is careful to note the language within the Optics itself and the actual conclusions to which Descartes is licensed. However, the three grades are often read in in a less than literal sense so as to provide for what might otherwise be a deficiency in Descartes’ theory of sense perception. I now consider such issues.

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Section 5

Hatfield and Epstein put Descartes’ theory of sensory perception among medieval and early modern thinkers who embrace the notion of a “sensory core,” the sensory core being that which “provides the raw material from which the mind generates the three dimensional visual world” (Hatfield and Epstein 1979, 369). According to their reading, the Sixth Replies foregrounds this aspect of Descartes’ theory. They write,

It should now be apparent that Descartes’ distinction between the second and third grades of sense corresponds to the distinction between the sensory core and the visual world. The second grade of sensation is a of the retinal image; the third grade is the ostensibly direct experience of solid objects at a distance, which actually results from unnoticed judgmental processes performed upon the unnoticed sensory core (Hatfield and Epstein 1979, 377).

Setting aside my disagreement about the grade to which the “representation of the retinal image” belongs, my reading finds common ground with theirs in the thought that there is a bit of phenomenal “raw material” upon which third grade judgments go to work.

However, my reading does not contend that third grade judgments produce any phenomenal characteristics whatsoever, and the same is true for my understanding of the

Optics. My interpretation of Descartes is thus notably deficient: it has yet to account for how pineal images are rendered phenomenally three-dimensional.

There are reasons other than the strictures of my interpretation for not wanting to locate the source of perceived three-dimensionality in the third grade or the mind in general, however. For one, putting this function in the third grade seems to ignore an important facet of what Descartes says in the Sixth Replies. In the passage just examined,

Descartes suggests that whatever a mind does at the third grade is under one’s control, at

125 least in a minimal sense. Only once a person grows accustomed to the ways in which the world deceives can one form a basis of judgment, and upon such experiential grounds someone voluntarily (however minimal it might be) recognizes that they are being fooled upon first sight of the bent stick. But, contra Hatfield and Epstein, if third grade sensations were meant to explain the production of phenomenal three-dimensionality, then third grade sensations turn out to be much more akin to the child’s perception, one not open to voluntary revision.

For another, Descartes writes that no “falsity can occur in” first and second grade sensations, the implication being that falsity can occur at the third grade. But if the third grade constructs the phenomenal characteristic of perceived three-dimensionality, then one seems to commit a simple category mistake, for falsity does not belong to phenomenal qualities themselves. It belongs to the beliefs or about those qualities. One does not judge that ‘the stick appears bent’ is wrong, but judges rather, say, that ‘the stick’s bent appearance rightly corresponds to world’ is wrong.119 Thus, Descartes suggests, according to my reading, that first and second grade sensations provide minds with everything they need to attribute truth or falsity to some phenomenal characteristic or other, and I believe this includes perceived three-dimensionality as well.

Overall, then, my reading resists the idea that Descartes means to explain how the material world comes to appear three-dimensional on three grounds. Doing most

119 Simmons addresses such a concern in her work on the topic. Like Hatfield and Epstein, she attributes perceived three- dimensionality to the mind’s action in what she calls “constructive judgments,” contrasting constructive judgments to “projective judgments,” the latter of which are attributions of truth-value. Accordingly, she writes, “Nor does the intellect’s constructive judgments make spatial perception epistemically reliable at the third grade of sensory perception. I mention above that Descartes routinely insists that projective judgments of both primary and secondary qualities lead to false beliefs. He similarly points out that constructive judgments involved in spatial perception are “very uncertain” and often lead to misperception (Dioptrics, AT VII 144; see also 147).” But I do not see clear evidence of Descartes committing to constructive judgments in the Sixth Replies or the Optics, so I cannot agree with her reading. See Simmons 2003A, 574 - 575. 126 resisting is my contention that the Optics’ account of common sensibles is not concerned with explaining how phenomenal characteristics are produced. It is rather interested in providing the mechanical affairs involved in evaluating the content of visual perception after phenomenal qualities are produced. The second reason comes from Descartes’ suggestion in the Sixth Replies that third grade sensations are voluntary in some sense, which misaligns with the plain fact that perceived three-dimensionality is out of one’s control. Finally, viewing the third grade as producing phenomenal three-dimensionality seems to confuse the grounds of truth-evaluation with truth-evaluation itself. But, then, where is the appearance of the third- according to my view?

The perceived third-dimension is in the retinal image. We saw earlier that the

Treatise includes distance among phenomenal features “occasioned” by the pineal gland. I think, however, that Descartes uses “occasion” here loosely, at least in regards to the gland’s “occasioning” of distance perception.120 For, as we saw in the previous section, the

Treatise claims forthrightly that humors “allows objects lying at different distances to paint their images distinctly on the back of the eye” and, in addition, claims that retinal images “represent” an object as closer or further away. Thus, at least in the Treatise, it appears that retinal images—and consequently pineal images—directly present distance and, therefore, three-dimensionality to minds. Moreover, the engraving analogy, as I read it, claims that pineal images encode perspectival information. The coffee cup’s rim appears elliptical instead of round because my retinas are impressed by a directional configuration originating from such-and-such angel rather than so-and-so angel, and, so,

120 I do not intend this statement to belie my claim in the previous chapter about Descartes’ use of ‘occasion’ in this passage from the Treatise. For his use of it surely references mere causal relations between motions in the pineal gland and some phenomenal characteristics, namely perceived color, smell, and so on. 127 in the Optics we also find some suggestion that Descartes put phenomenal three- dimensionality in physical images.

This might be an unsatisfying reading for some, especially since readers are sorely lacking the details of how a two-dimensional image can possibly present the richness of three-dimensions. However, two points are worth noting in response. First, my appeals to Descartes’ physiological descriptions in the Treatise and Optics are but the top layering of my reading. The foundational reasons, at least to my mind, for thinking that Descartes ascribes perceived three-dimensionality to pineal images are (a) Descartes’ language of evaluation within the Sixth Discourse and (b) his claim that third grade sensations are somehow voluntary (and thus involve acts of truth-evaluation). The alternative option, then, is that physical qualities are solely responsible, and Descartes’ comments on distance perception in the Treatise and the engraving analogy provide some evidence for such a claim.

Second, locating the source of perceived three-dimensionality in minds appears guilty of ascribing to Descartes a “dustbin” in regards to a perceived quality that need not be assigned to the dustbin. The dustbin theory is characterized (and endorsed) by Nicolas Jolley as follows: “Descartes subscribed to what might be called a dustbin or grab bag conception of mind. The items that fall under the umbrella of the mental, for Descartes, are whatever is left from the picture of the world once matter is defined in purely geometrical terms” (Jolley 2000, 57). For the purposes here, this criticism of Descartes (which originates with Nicolas Malebranche) accuses Descartes of sweeping into minds whatever features of visual perception he could not intelligibly

128 mechanize. But one ought to avoid reading Descartes as a dustbin theorist, at least in regards to perceived three-dimensionality. Not only is the interpretation uncharitable, but, moreover, Descartes, at least in principle, could mechanize perceived three- dimensionality because the physical world is in fact three-dimensional. Thus, if minds project the third-dimension, then Descartes throws something into the dustbin which, by his own principles, he should not. Exactly how Descartes thought to mechanize perceived three-dimensionality is no doubt mysterious, but it is no less mysterious than treating it as a product of the mind

Defending the presentation thesis as Descartes’ own view thus takes a bit of work, as readers can tell. However, in the next chapter, I show that one of Descartes’ most notable followers adopts parts of the view as well. Let’s now turn to Nicolas

Malebranche’s version of Cartesianism in order to see what he values about the presentation thesis and why he endorses parts of it for his own view.

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Chapter 4: the Divine Pineal Gland

Nicolas Malebranche’s philosophy is one of the early modern period’s more (if not most) radical adaptations of Cartesianism. This standing is achieved largely in virtue of his views on causation and sensory perception. In regards to causation, Malebranche endorses occasionalism, a view denying genuine causal power to created minds and, conjointly, ascribing any and all causal powers to God alone. In regards to sensory perception, Malebranche (arguably) posits that the direct intentional object of perceived shape is an idea in God but, nonetheless, locates perceived color in minds. This second component of Malebranche’s philosophy, called the “vision in God” doctrine, has an obvious structural similarity to my reading of Descartes. It bifurcates the ontology of visual shape perception in two, locating the object of perceived shape in something external to the mind yet locating perceived color within the mind itself. In this chapter I discuss possible motivations for Malebranche’s adherence to the structure of Descartes’ theory of sensory perception.

My discussion falls into three parts. In the first, I review notions specific to the vision in God doctrine and discuss the doctrine’s textual sources. In the second section I argue that Malebranche recognizes and rejects the physiological commitments of the presentation thesis. In the final section I argue that one evident and plausible reason for

Malebranche’s endorsement of Descartes’ structure of sensory perception—but rejection

130 of its details—derives from the epistemic reliability that both he and Descartes assign to resembling causes.

Section 1

Malebranche introduces the vision in God doctrine by writing that, “When we perceive something sensible, two things are found: sensation and pure idea” (LO 234). As has arrested interpreters ranging as far back as Locke and Berkeley, Malebranche’s ontology of “pure ideas” dramatically departs from Cartesian orthodoxy.121 He writes,

As for the idea found in conjunction with the sensation, it is in God, and we see it because it pleases God to reveal it to us. God joins the sensation to the idea when objects are present so that we may believe them to be present and that we may have all the feelings and passions that we should have in relation to them (LO 234).

Traditionally, Malebranche’s doctrine is read as partitioning the ontology of visual sensory perception in a way broadly similar to my reading of Descartes: when perceiving secondary qualities the soul perceives something in itself (what I call “sensation proper”), but when perceiving primary qualities minds are directed to something extra-mental.122 I adopt this traditional understanding in the following pages with little critical defense, but nonetheless hope that the examined passages clearly demonstrate the interpretation’s plausibility.

121 Locke in fact penned a lengthy essay in response to Malebranche’s vision in God doctrine, while Berkeley’s notebooks contain numerous references to Malebranche. See Locke 1823 and Berkley 1947. 122 For examples of the traditional reading within the last century, see Church 1931, 228 – 230; Hobart 1982, 86 – 87; McCracken 1983, 70 – 72; Nadler 1989, 66 –67; Peppers-Bates 2009, 20 – 21; Pyle, 61 – 66; and Radner 90 – 94. However, this interpretation has received some notable challenges within the last thirty years. In his Malebranche and Ideas, argues that the vision in God doctrine makes no claims about the intentional object of visual sensory perception, but is instead meant only to establish the ontological status of clear ideas. See, for example, Nadler 1992, 7. Tad Schmaltz, as well, challenges the centrality of visual intentionality to the doctrine, suggesting that, overall, it is rather a doctrine about causation. See Schmaltz 2000, 80 – 81 David Scott has endorsed Nadler’s reading, seeing it as “obvious.” See Scott 2001, 67 - 68. For a brief overview of the debate, see Pessin 2006. Finally, at least to my knowledge, scholarship on the matter has not suggested that Malebranche adopted the structure of Descartes’ theory of sense perception. This is to be expected, though, considering the reputation of the presentation thesis within Descartes scholarship. 131

Accordingly, in the Elucidations to the Search after Truth Malebranche responds to an objection put forth by Arnauld.123 Malebranche summarizes the objection in this way:

Nothing in God can be moved, nothing in Him can have figure. If there is a sun in the intelligible world, this sun is always equal to itself. The visible sun appears greater when it is near the horizon than when it is at a great distance from the horizon. Therefore, it is not this intelligible sun that we see. The same holds true for other creatures. Therefore, we do not see God’s works in Him (LO 626).

In form, Arnauld’s objection is a straightforward modus tollens:

(1) If the visible sun is God’s idea, then the visible sun’s apparent size is immutable.

(2) The visible sun’s apparent size is not immutable.

(3) Therefore, the visible sun is not God’s idea.

Arnauld’s objection is motivated by an apparent conflict between God’s immutability and the vicissitudes of visual appearance. As the argument goes, God’s ideas are unchangeable, and so if the perceived borders of the visual sun are a feature of God’s ideas, then the sun should not appear larger in morning than it does in the afternoon.

Malebranche replies to the objection by claiming that a misunderstanding motivates

Arnauld. According to Malebranche, Arnauld mistakenly assumes that the ideas relevant to visual sensation are static, cookie-cutter like entities, that they are discrete and particular bits of divine extension. But, for Malebranche, this assumption is at odds with the truth.124

As Malebranche states in his response, there is a single idea to which minds are

123 Malebranche’s first and most important work is the Search after Truth, first published in 1674. The Elucidations to the Search after Truth was published alongside the Search’s third printing in 1677. The Elucidations are Malebranche’s public responses to criticisms put forth by various objectors. 124 It is worth noting that this is not Malebranche’s only option. One way for Malebranche to undo the worry is by digging in his heels and claiming that God has a different idea for every possible combination of extended size and shape. Nonetheless, this would have gotten him into further difficulty, for the worrisome implication now appears to be that God’s knowledge is of particulars, despite the common supposition that God’s knowledge is of universals. For more on this difficulty in Malebranche see Pyle 2003, 61 - 62. 132 directed when perceiving apparent shape—not an overpopulated menagerie of ideas.125

This idea, called “intelligible extension,” is infinite in “intelligible” dimensionality, and therefore has no particular boundaries in and of itself. Apparent changes in size or shape are thus just a matter of how much and in what way God reveals intelligible extension.

God’s ideas, then, do not change, but rather the mind's relation to God’s idea change. For

“…the mind can perceive a part of this intelligible extension that God contains, [and so] it surely can perceive in God all figures; for all finite intelligible extension is necessarily an intelligible figure, since figure is nothing but the boundary of extension” (LO 626). The apparent change of the sun’s size throughout the day, then, is actually a series of changes in the perceived circumference of some portion of intelligible extension. Moreover,

Malebranche packages an account of perceived change in shape (alongside size) when introducing intelligible extension, since, as he writes, intelligible extension can“...serve to represent the sun, or a horse, or a tree (LO 627),” or any figure whatsoever.

God, then, does for Malebranche what the pineal gland does for Descartes. God is that to which minds are directed when perceiving figures or shapes. Now, part of

Malebranche’s motivation for locating intentionality in God, no doubt, comes from his general aspiration to develop a thoroughly theocentric form of Cartesianism. However, if one seeks philosophical rather than theological reasons for his ontology of visual perception, then certainly more should be said. First, why is the intentional object of perceived shape in God? Why does Malebranche not locate it in finite minds, or even in the brain as Descartes does? Second, why is the intentional object of perceived shape in

God? Why does Malebranche ontologically isolate this one feature of visual perception in

125 Whether or not, as Malebranche claims, the notion of intelligible extension was presumed in the first two printings of the Search is questionable. However, little hangs on this and exploring it takes us too far astray. 133 much the same way that Descartes did in his presentation thesis?

My contention is that Malebranche’s central motivation for endorsing Descartes’ structure of intentionality is rooted in two conflicting commitments. On the one hand,

Malebranche endorses the broadly Cartesian thesis that resembling causes are genuine and reliable sources of knowledge, but, on the other hand, denies that bodies produce knowledge. In the next section I discuss Malebranche’s reasons for the latter claim, and in doing so show that Malebranche specifically rejects the physiology of the presentation thesis.

Section 2

Malebranche’s denial that bodily substances produce knowledge is a straightforward consequence of his occasionalism: bodies are not genuine causes and, therefore, bodies do not cause knowledge. However, before discussing Malebranche’s arguments for occasionalism and how they fit with his epistemic views, I attend first to an interesting passage from the Search after Truth in which Malebranche argues against positions similar to the presentation thesis (which, in turn, leads us to occasionalism).

In Book II of the Search, Malebranche discusses the faculty of imagination, which, following standard Cartesianism, he claims is tied closely to the faculty of sensation.

Considered as mental faculties, both imagination and sensation are imagistic capacities

(among other things), while from a physiological perspective, both faculties depend on the

134 motion of animal spirits within the “principal part of the brain.”126 Thus, as was the case for Descartes, Malebranche’s comments on the relation between minds and the brain in imagination have bearing on views like the presentation thesis.

Accordingly, in Book II, Part I, Chapter IV of the Search, Malebranche considers ways in which brain traces (or images) might be relevant to mind-body interaction. He writes,

As soon as the soul receives some new ideas, new traces are imprinted in the brain; and as soon as objects produce new traces, the soul receives new ideas. It is not that it considers these traces [considere ces traces], since it has no knowledge of them; nor that these traces include these ideas, for they have no relation to them; nor, finally, that the soul receives its ideas from these traces: for, as we shall explain in the third book, it is inconceivable that the mind receive anything from the body and become more enlightened by turning toward it, as these philosophers claim who would have it that by transformation to fantasms, or brain traces, per conversionem ad phantasmata, that the mind perceives all things. But that all takes place according to the general of the union of soul and body, which I shall also explain in the third book. (LO 102). 127

In saying that the “soul receives new ideas” because “new traces are imprinted in the brain,” Malebranche roughly commits to Cartesian physiology. He accepts the notion that

“traces,” “figures,” or “images” factor into the general causal history of an idea.128

Moreover, the passage posits and, in turn, rejects three different ways of thinking about how brain traces might function in mind-body interaction: (a) minds might “consider” brain traces, (b) brain traces might “include” ideas, and (c) minds might “receive” ideas from brain traces. The first is of most interest, for it gestures toward the presentation thesis.

As one might remember, Descartes’ earliest mention of the presentation thesis occurs in the Treatise, and its precise vocabulary is a point of convergence with

126 This is not the only difference between the two. Both Descartes and Malebranche believe that voluntariness serves as a benchmark distinction as well. In addition, it is worth noting that Malebranche is not as pro-pineal gland as Descartes, and therefore openly considers competing views on the “principal part of the brain.” See LO 89. 127 Malebranche claimss here that minds are not “enlightened” by the body and, so, denies that bodies cause knowledge. I arrive at his reasoning for this claim shortly. 128 The context makes clear that Malebranche is using “idea” here in its broad sense, namely as a way of referring to an immediate object of perception, whether immaterial or not. See LO 217 for Malebranche’s understanding of ‘idea’. 135

Malebranche’s, for in the Treatise Descartes writes,

That is to say, it is only the latter figures [i.e. images on the pineal gland] which should be taken to be the forms or images which the rational soul united to this machine [i.e. the human body] will consider [considérera] directly when it imagines some object or perceives it by the senses (AT XI 177 / CSM 2 106 / G 149).

Thus, when Malebranche writes that “It is not that it [the mind] considers these traces

[considere ces traces],” he denies that minds “look at” brains, that is, he denies views like the presentation thesis.129 Thus, let’s plausibly conjecture that Malebranche is simultaneously stating his awareness and rejection of something like the presentation thesis here in his comments on imagination, for, as I now demonstrate, doing so yields interesting results.

As a simple reconstruction of the “brain traces” argument shows, Malebranche puts heavy stock in “knowledge” for determining whether or not minds “consider” brain traces:

(1) If minds “consider” brain traces, then they must have “knowledge” of those traces.

(2) Minds do not have “knowledge” of those traces.

(3) Therefore, minds do not “consider” brain traces.

In general, the first premise assumes that if minds “consider” x, then minds must have some “knowledge” about x. But the motivation for this principle is obscure, at least at first pass. Thus, aiming to illuminate his reasoning, Malebranche shortly thereafter compares the “brain traces” argument to his views on causation,

129 As some , the Treatise on Man was Malebranche’s first encounter with Descartes’ work, so one might find it of little surprise that he uses the Treatise’s own terminology to zero in on the thesis he aims to reject. See Nadler 2000, 3. In addition, it should be noted that this “brain traces” passage from the Search does not suggest that he actually read Descartes as endorsing the presentation thesis, but that he is rather, perhaps, aware of those understanding Descartes in such a way or is aware of other philosophers saying as much. 136

Likewise as soon as the soul wills that the arm be moved, it is moved, even though the soul does not know what it must do in order to move it; and as soon as the animal spirits are agitated, the soul is affected, even though it might not even know whether there are animal spirits in its body (LO 102).

Following Malebranche’s suggestion, then, I now turn to his views on causation—and thereby his arguments for occasionalism—so as to clarify why he rejects views like the presentation thesis.

Malebranche provides at least four distinct arguments for occasionalism. Some arguments ramify over all causal interaction, while others just extend over a single causal direction.130 The latter type is significant here, and, in what follows, I consider arguments against both causal directions; that is, I consider both Malebranche’s argument against mind-to-body causation and his argument against body-to-mind causation. Following

Sukjae Lee, I call the former the No Knowledge Argument and the latter the Passive

Natures Argument. 131 I attend first to the former.

Although Malebranche gives a version of the No Knowledge Argument in the

Search, it is but a quick passing compared to argument’s fuller elaboration in Elucidation

XV, and so I give attention to the latter. Accordingly, Malebranche writes in the

Elucidations,

But I deny that my will is the true cause of my arm’s movement, of my mind’s ideas, and of other things accompanying my volitions, for I see no relation whatever between such different things. I even see clearly that there can be no relation between the volition I have to move my arm and the agitation of the animal spirits, i.e., of certain tiny bodies whose motion and figure I do not know and which choose certain nerve canals from a million others I do not know in order to cause in me the motion I desire through an infinity of movements I do not desire (LO 669).

As was the case in the “brain traces” argument, Malebranche appeals to “knowledge” here.

130 Malebranche’s appeal to continuous creation, for example, is commonly understood to ramify generally. See JS 115 - 116 for his continuous creation argument. 131 See Lee 2016. 137

However, the principle motivating the appeal to “knowledge” in the present passage is comparatively more lucid. For in this passage Malebranche plainly appeals to what I call the “Knowledge Principle,” the claim that, in order to count as a cause, minds must know in the fullest terms possible how to bring about an effect.132 Thus, the reason that

Malebranche denies mind-to-body causation boils down to the fact that one does not grasp the minutiae and particularities of those mechanical interactions required to move even one particle, let alone those required to move an arm!

What makes the Knowledge Principle plausible for Malebranche is the denial of blind . Malebranche, like many of his contemporaries, believes that in order for an agent’s willing to be efficacious, the willing’s content must adequately describe the intended effect.133 According to a thin construal of the notion, the action of moving one’s arm is caused, in part, by one’s willing to ‘move my arm’ (or some synonymous description). But, as one can tell, Malebranche has no thin construal in mind. He posits that the content of one’s willing has to contain the full-list of mechanical requirements to move one’s arm. Thus, Malebranche’s strict notion of agency (contained within the

Knowledge Principle) eliminates the possibility of attributing causal powers to woefully under-informed finite minds. What role, then, is this Knowledge Principle playing in the

“brain traces” argument?

In the No Knowledge Argument Malebranche appeals to one’s inability to discern the mechanical details required to bring about physical change. But this does not appear to be the point Malebranche relies on in the “brain traces” argument. In the scenario relevant to the “brain traces” argument, minds are not trying to move anything, but rather

132 Again, I follow Lee’s construal (but not his precise formulation). 133 For Malebranche’s concession to the denial of blind agency see LO 5. 138 attempting to be aware of something. Thus, one might offer, as a first pass, the following more specific construal of the first premise in the “brain traces” argument: if minds

“consider” brain traces, then minds must be aware of brain traces. However, such a construal fails to track the stringency of the Knowledge Principle. One can be aware of something without knowing everything about it, just as one can move their arm without knowing precisely how one’s body does it (at least in a non-Malebranchean reality). Thus, since Malebranche certainly does not think created minds genuinely cause their body’s movement, he probably does not think that basic awareness does the trick either. Thus, being sensitive to such a concern, Malebranche’s first premise in the “brain traces” argument should look more like this: if minds “consider” brain traces, then minds are aware of everything about those brain traces. The argument, then, in its most specific form is:

(1) If minds are directed toward brain traces, then they must be aware of everything about

those brain traces.

(2) Minds are not aware of everything about those brains.

(3) Therefore, minds are not directed toward brain traces.

In the end, Malebranche denies views like the presentation thesis because he has as strict restrictions on what it means to be aware of something as he does on what takes to move something.

The argument succeeds at getting Malebranche his conclusion. For even if one were to maintain that they are aware of the fact that they are aware of brain traces, one could not plausibly go on to claim that they are aware of everything about those brain traces. However, in some ways the demands of the first premise play against

Malebranche’s own commitments. Malebranche, after all, argues that minds are 139 immediately directed toward God, and there are few people aware that they are aware of

God, and even fewer who are aware of everything about God (a claim likely to involve one in heresy). Perhaps there are resources that help Malebranche avoid this tension, but, if so, they are not pursued here. Rather, it is more pertinent to note how one feature of the

“brain traces” argument turns out to be of aid in replying to an objection lodged against the presentation thesis.

It is sometimes thought that the presentation thesis belies Descartes’ commitment to the transparency of . Wilson, for example, says this about the matter:

Apart from its intrinsic strangeness, the presentation conception seems to conflict with a fundamental Cartesian doctrine about the mind. The Cartesian mind is, after all, supposed to be conscious of its perceptions. Yet it seems that we, as minds, are not conscious of these brain state perceptions or of “receiving” signs from the brain, but only of cups and saucers, tables and chairs, other human bodies, and the like (Wilson 1991, 308).

But I think that Wilson is making Descartes out to be more Malebranchean than he is, for one general lesson of the “brain traces” argument is that awareness comes in degrees. One could be aware that they are aware of shape, or they could be aware that the shape of which they are aware is a shape on the pineal gland, and so on. But where to locate

Descartes’ view of transparency on the scale of awareness is tricky, at least in regards to sensory perception. In the previous chapters, we have seen Descartes claim, among other things, that one is not initially aware that sensations proper fail to resemble their causes, that young children and fools are not conscious of the fact that partially submerged sticks are not bent, and, most importantly, that minds are directed toward the pineal gland

(even though one might not be aware that they are). Thus, although Descartes posits some degree of transparency, it is clear that he is no Malebranchean on the matter. I contend, then, that the issue of transparency in regards to sensory perception be 140 determined not from the top, but instead from the bottom, by noting specific cases in which Descartes suggests that minds are not aware. And doing so—as we have in previous chapters—suggests that Descartes takes consciousness to be much less transparent than

Malebranche does.

In recognizing how the “brain traces” argument helps respond to this objection, however, one realizes that Malebranche’s argument actually fails as an argument against the presentation thesis. Malebranche’s argument faults the mind for its inability to attend to the pineal gland, but according to the presentation thesis, minds are not responsible for bringing about the intentional relation in the first place. Rather, powers of the gland itself bring about the relation. Thus, in order for Malebranche’s argument to succeed against the presentation thesis, he needs to argue against it on the grounds of body-to-mind interaction. To my knowledge, Malebranche does not provide a direct argument against views like the presentation thesis based on the appropriate causal direction.134

Nonetheless, Malebranche’s general argument against body-to-mind causation succeeds at doing the job. Thus, let’s now turn attention to the Passive Argument.

The Search includes a kernel of the Passive Natures Argument:

We have only two sorts of ideas, ideas of minds and ideas of bodies; and as we should speak only of what we conceive, we should only reason according to these two kinds of ideas. Thus, since the idea we have of all bodies makes us aware that they cannot move themselves, it must be concluded that it is minds which move them (LO 448).

By thinking upon one’s clear and distinct idea of matter, one immediately realizes that bodies lack the power to produce or communicate motive force. However, this form of

134 Nadler provocatively suggests that Malebranche might apply the No Knowledge Argument to bar body-to-mind causation as well. But Nalder himself admits this reading is speculative at best. See Nadler 1999, 274. 141 the argument only rejects body-body causation, failing to make the leap to body-to-mind interaction. Thus, in the Elucidation XVI, Malebranche takes the argument further,

But when I consult my reason I clearly see that since bodies cannot move themselves, and since their motor force is but the will of God that conserves them successively in different places, they cannot communicate a power they do not have and could not have communicate even if it were in their possession. For the mind will never conceive that one body, a purely passive substance, can in any way whatsoever transmit to another body the power transporting it (LO 660; emphasis added).

Causal efficacy is thereby removed from the physical world. By their very nature, bodies cannot causally interact with one another. A rejection of body-to-mind causation obviously follows from Malebranche’s claims here, but, oddly enough, he fails to explicitly draw out this conclusion in passages related to the one above. However, in his later work, the on Metaphysics and on , Malebranche is sure to include a straightforward avowal of the conclusion. Theodore, Malebranche’s mouthpiece in the

Dialogues, includes the conclusion when he rehearses the argument for his student

Aristes, stating,

THEODORE: Once again, think about it. Consult the idea of extension and decide by this idea which represents bodies—if anything does—whether they can have any property other than the passive faculty of receiving various figures and movements. Is it not entirely obvious that all the properties of extension can consist only in relations of distance? ARISTES: That is clear, and I have already agreed with it. THEODORE: Thus it is impossible for bodies to act on minds (JS 106).

Thus, as the Passive Natures Argument goes, by reflecting upon the nature of bodies one immediately recognizes that bodies are entirely passive and thereby lack any causal power whatsoever, in turn ruling out body-to-body causal interaction as well as body-to-mind causation.

Earlier I claimed that Malebranche’s occasionalism implies that bodies cannot produce knowledge. As things stand at the moment, though, this seems a tenuous

142 conclusion at best, especially since the No Knowledge Argument has minimal relevance and, moreover, since the Passive Natures Argument makes no explicit attempts to draw this point out. However, by the time of the Dialogues’ writing, Malebranche appears to have been worried about the matter specifically, and he worried about it because he also believed that knowledge of geometrical derives, in part, from causes resembling the physical world. I now move to these concerns.

Section 3

In V Malebranche wrestles with an apparent tension in his commitments.

On the one hand, he finds himself insisting that knowledge of abstract geometrical principles can be derived directly from visual demonstrations like those in Euclid’s works.

Yet, on the other hand, Malebranche finds himself steadfastly committed to the epistemic nullity of sensation and imagination (conceived as secondary qualities), as the dramatics of Aristes attest, “Yes, Theodore, what pleasure I have in telling you: our mind is only darkness, its own modalities do not enlighten it, its substance, as completely spiritual as it is, contains nothing intelligible; its senses, imagination, and passions seduce it at every moment (JS 71).” Worries such as these, I argue, are also present for those reading

Descartes as lumping all physical causes under non-resembling causes, but not for those readings favoring the presentation thesis. In light of this similarity, I conclude that

Malebranche endorses the structure of the presentation thesis so as to avoid these worries, and that, consequently, Malebranche was pressured to “divinify” the pineal gland in virtue of his occasionalism. 143

Accordingly, early in Dialogue V Aristes, in his characteristic over exaggeration, swears off any potential contribution from creaturely minds:

Thus, the extension I see or sense does not belong to me. Otherwise, in contemplating myself I would be able to know God’s works. In attentively considering my own modalities I would be able to learn physics and many other which consist simply in the knowledge of relations of extension, as you well know. In short, I would be a light unto myself, which is something I cannot contemplate without a kind of horror (JS 76).

The “kind of horror” that shakes Aristes is the supposition that modalities of finite minds immediately assist in one’s understanding of abstract truths. In saying this, he rules out an entire ontological class as possible causal sources for mathematical knowledge. Thus, black and white lines of geometrical demonstrations appear to be just like bitter and sweet tastes: they contribute nothing to one’s grasp of truth. What one sees here, then, is a very

Cartesian assumption: certain types of knowledge require certain types of causes. But God is the only cause in Malebranche’s world, and so if one in fact derives geometrical truth directly from drawings and imaginings, then God must somehow be “in” the black and white lines. As one can probably gather, Malebranche believes that, indeed, God is “in” visual geometrical demonstrations insofar as intelligible extension is “in” them, a point

Theodore makes explicit in his summary of the dialogue so far,

Thus you need not be surprised, my dear Aristes, that you can learn some evident truths by the of the senses. For although the substance of the soul is not intelligible to the soul itself and its modalities cannot enlighten it, because these very modalities are joined to the intelligible extension which is the archetype of bodies and because they make this extension sensible, they can show us its relations, in which the truths of geometry and physics consist. But it is always true to say the soul is not its own light unto itself, that its modalities are but darkness, and that it discovers exact truths only in the ideas Reason contains (JS 77).

Theodore adds to these comments a bit later in the dialogue, saying to Aristes this time:

However, let us return to the sensible demonstration I gave you of the equality that exists between the square on the diagonal of a square and the two squares on the sides. And let us take note that this demonstration derives its evidence and generality only from the clear and general idea of extension, from the straightness and equality of the lines and the rightness and equality of the angles and triangles, and by no means from the white and black which make all these things sensible and particular without making them more intelligible or clear by themselves (JS 78 - 79). 144

Malebranche avoids the difficulty that he presents at the outset, then, by claiming that the only feature of geometrical demonstrations causally contributing to geometrical understanding is the “straightness and equality of the lines.” In other words, the only genuinely causal feature of visual geometrical demonstrations is the perceived extension of perceived color—not the perceived color of perceived extension. But in this response,

Malebranche also makes a claim about intentionality. He claims that visual geometrical demonstrations cause geometrical knowledge insofar as one is immediately visually aware of something resembling the physical world. 135 By locating this resembling item within

God’s idea of intelligible extension, Malebranche is thereby also avoiding a possible problem confronting more standard readings of Descartes.

I begin articulating this problem by quoting Simmons,

Perhaps the most distinctive feature of spatial perception from an early modern point of view is the fact it is bound up with secondary qualities: I see pink hearts, yellow crescents, orange stars and green clovers. The precise nature of the relation between these two aspects of sensory experience is fraught with interpretive difficulties that I must put aside for the present purposes (Simmons 2003B, 420 en 8).136

Malebranche’s discussion of visual geometrical demonstrations gestures at one such

“interpretive difficulty.” The difficulty is this: how can a direct intentional object resemble the physical world if the intentional object is a mode something that itself, in principle, cannot resemble the physical world? We saw that Malebranche avoids this difficulty by putting the direct intentional object of shape in intelligible extension and, in turn,

135 I am, of course, assuming that visual geometrical demonstrations resemble the physical world. I do not take this to be too problematic an assumption, however. 136 “Pink hearts, yellow crescents, orange stars and green clovers?” It appears that Simmons may have Lucky Charms on the mind. 145 locating the cause of geometrical knowledge in God.137 However, such a readily available answer does not seem forthcoming to some interpretations of Descartes.

As Simmons’ quote suggest, a general feature of readings supposing that, for

Descartes, all physical causes are non-resembling ones is that perceived primary qualities come prepackaged with perceived secondary qualities. But if perceived shape is “bound up” with perceived secondary qualities, then such interpretations confront the difficulties of Dialogue V. They commit to locating perceived qualities that resemble the material world in something that cannot itself resemble extension.138 Moreover, if perceived shape is the same in ontological kind as perceived secondary quality, then why is the former more epistemically reliably than the latter? For, in making this claim about reliability,

Malebranche was simply following a lesson of article 69 in the first part of Descartes’

Principles,

69. We know size, shape and so forth in quite a different way from the way in which we know colours, and the like.

This will be especially clear if we consider the wide gap between our knowledge of those features of bodies which we clearly perceive, as stated earlier, and our knowledge of those features which must be referred to the senses, as I have just pointed out. To the former class belong the size of the bodies we see, their shape, motion, position, duration, number and so on...To the latter class belong the colour in a body, as well as pain, smell, taste and so on. It is true that when we see a body we are just as certain of its existence in virtue of its having a visible colour as we are in virtue of its having a visible shape; but our knowledge of what it is for the body to have a shape is much clearer than our knowledge of what it is for it to be coloured (AT VII 33 – 34 / CSM 1 217 – 218).139

Of course it remains true under such interpretations that one reason visually perceived shape is more reliable than perceived color is that the former resembles the material world

137 It might appear odd for Malebranche to claim as much, for he puts resembling causes in God’s idea of intelligible extension, something that is not extension itself. Nonetheless, Malebranche obviously intends intelligible extension to function as a sort of ersatz realm capable of having spatial properties. 138 Considering that formal reality is the reality something has in virtue of existing, while objective reality is the reality something has in virtue of being a representation (and, thus, ideas have both formal and objective reality), we can also phrase the question as such: how can something qua objective reality represent the very features of a formal reality it cannot itself possess? See AT VII 40 – 41 / CSM 2 28 29 for Descartes’ distinction between objective and formal reality. 139 The passage to which Descartes refers is part 1, article 48 of the Principles. See AT VIIA 23 / CSM 1 208 – 209. 146 but the latter does not. But this is not the heart of Malebranche’s concern. Part of his worry is that resemblance is not enough to confer epistemic reliability to one but not the other, for, he contends, the epistemic reliability of resemblance relies on the ontology of what one perceives, for resemblance is a feature shared only between things that can resemble one another. Thus, if one interprets Descartes as lumping all physical causes under non-resembling causes, then Malebranche seems to have corrected Descartes’ view rather than merely modifying it.140

However, the presentation thesis avoids the difficulties raised by Malebranche in

Dialogue V since it does not put resemblance in something that cannot resemble.

According to the presentation thesis, minds are directly aware of something that can resemble objects out in the world—the surface of a straddling mode. Moreover, endorsing the presentation thesis can explain, on ontological grounds, why perceived shape is more epistemically reliable than perceived secondary qualities. When visually perceiving shape, minds are directly attending to something in direct contact with the physical world, and in virtue of this fact, minds are reliably informed about features of the material world.

In the end, then, Malebranche endorses the structure of Descartes’ intentionality of sensory perception because he sought a structure that could explain on ontological grounds why perceived secondary qualities are epistemically vacuous yet perceived shape epistemically reliable. Such a theory, at least by Malebranche’s lights, requires dividing up the ontology of what one perceives, a feature offered by views like the presentation thesis.

But Malebranche could not follow the presentation thesis in full, for Malebranche’s “brain

140 Dominick Iorio reads Malebranche (of the Search) as opposing Descartes in a similar way. However, according to Iorio, the problem that Malebranche has with Descartes is not about resembling causes, but one about resembling God’s powers. He writes that “…Descartes would have the soul be the intelligible world which comprehends within itself everything included in the material and sensible world. But for Malebranche this is vanity sprung from a love of independence and a desire to resemble God” (Iorio 1966, 36). 147 traces” argument bars the pineal gland from intentionality while his occasionalism strips the gland of causal power. Malebranche thus had little other recourse than to “divinify” the pineal gland.

148

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