Was Spinoza a Naturalist?

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WAS SPINOZA A NATURALIST?

ALEXANDER DOUGLAS

Abstract: In this article I dispute the claim, made by several contemporary scholars, that Spinoza was a naturalist. ‘Naturalism’ here refers to two distinct but related positions in contemporary philosophy. The first, ontological naturalism, is the view that everything that exists possesses a certain character (variously defined) permitting it to be defined as natural and prohibiting it from being defined as supernatural. I argue that the only definition of ontological naturalism that could be legitimately applied to Spinoza’s philosophy is so unrestrictive as to tell us nothing about the content of his ideas. The second, methodological naturalism, is the view that the natural sciences are the best means of finding out substantial truths about the concrete world. I present some historical research showing that Spinoza’s way of positioning himself with respect to other philosophers in the Dutch Republic casts very serious doubt on the claim that he was a methodological naturalist. This adds further weight to arguments that have already been made against the naturalist reading of Spinoza.

Introduction

One thing that is often said of Spinoza is that he was a naturalist.1 This claim is important in the context of contemporary analytic philosophy, where naturalism is something of an industry standard. Jack Ritchie suggests that:

. . . if you were to ask a contemporary philosopher in the English-speaking world – one of the living and thus not so great – to classify her philosophical position, I would wager that the most common answer would be: ‘I’m a naturalist’.2

The suggestion that Spinoza was a naturalist therefore suggests that he held something close to the outlook of a contemporary analytic philosopher – a great philosopher, someone like Ritchie might say, who thought like today’s not so great ones.3 I would like here to examine this suggestion

1 2 PACIFIC PHILOSOPHICAL QUARTERLY and then repudiate it. I shall first explore what it means to claim that Spinoza was a naturalist, in the various senses in which contemporary analytic philosophers use that term. I shall then show how taking Spinoza as a naturalist in any of those senses fails as a useful characterization of his philosophy, especially when we examine it in its historical context. More specifically, I shall argue that Spinoza is neither an ‘ontological’ nor a ‘methodological’ naturalist. The former kind of naturalist is, roughly, one who believes that the only existing entities are those currently recognized by the natural sciences, with allowances made for the possibility of unforeseen scientific advances. Spinoza’s philosophy, I shall argue, is deeply committed to the existence of some entities that are recognized neither by contemporary natural science nor by the natural science of Spinoza’s day (insofar as there was such a thing). A methodological naturalist is one who believes that the methodology common and special to the natural sciences is the only one appropriate for discovering substantial truths about the concrete world. It is highly doubtful that there is a single method or even family of methods precisely fitting this profile. Neverthe- less, I shall argue, one may characterize the common and special methodology of the natural sciences as ‘empiricism’, provided the latter is defined with sufficient breadth. There is considerable scholarly debate concerning the degree to which Spinoza was an empiricist. I aim to advance this debate by placing Spinoza’s work in its historical context, an exercise that highlights its distinctly non- and even anti-empiricist elements.

Ontological naturalism

Who are the contemporary naturalists, and what do they believe? Defining naturalism is more difficult than applying the label in a generally accepted fashion.4 It is usually said that there are two distinct kinds of naturalism. One involves a certain kind of methodological commitment to natural science as the best or only way to learn about the natural world. The other involves an ontological thesis, to the effect that there are no supernatural entities. When one comes to define ‘supernatural’, however, it is tempting to place in the realm of the supernatural everything that is beyond detec- tion by the methods of natural science. But in that case committing to ontological naturalism seems to require a rejection of the methodological variety. If the realm of the supernatural is, by definition, populated entirely by things inaccessible to scientific knowledge, then the limitation of all knowledge to the scientific variety rules out our knowing what, if anything, resides in that domain. In confidently asserting that nothing resides there, ontological naturalism makes an implicit claim to the pro- hibited knowledge. Since ontological naturalism appears thus the more

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 3 forthright of the two species, I shall begin by assessing the claim that Spinoza was an ontological naturalist. One version of ontological naturalism identifies itself, or at least regards it as overlapping considerably, with physicalism. Mario de Caro and David Macarthur note that ‘[i]n the recent past . . . the terms “naturalism” and “physicalism” have often been used interchangeably’.5 Unfortunately, ‘physicalism’ is not much easier to define than ‘naturalism’. As a working approximation, De Caro and Macarthur use David Armstrong’s definition: physicalism is the view ‘that the world contains nothing but the entities recognised by physics [i.e., physical entities]’.6 We might allow that what Spinoza regarded as things conceived under the attribute of extension should count as physical on this definition. Cartesian physics suggested that extension and physicality amount to much the same thing and studied physical things as essentially extended things.7 Since Spinoza believed that the whole of nature could be conceived under the attribute of extension,8 we might conclude that he believed it to be, in its entirety, the kind of entity recognised by Cartesian physics. But this might not be enough to qualify Spinoza as a physicalist, since for him, nature also could also be conceived under the attribute of thought, through which it appears distinctly non-physical on Armstrong’s definition.9 Some scholars, however, have argued that, despite apparent objections arising from the attribute of thought, the proper reading of the Ethics in fact reveals a physicalist vision of reality. Edwin Curley, for example, argues that since Spinoza claimed that each mode of thought is identical with some mode of extension he in fact held the view that everything in the world is physical, including mental states, which are ultimately reducible to bodies or bodily affections.10 Curley is presumably interpreting Spinoza as a physicalist along the lines of the view espoused by identity theorists such as U. T. Place and J. J. C. Smart.11 Michael Della Rocca, however, denies that Spinoza should be read as a physicalist of this kind. He stresses that, unlike modern identity theorists, Spinoza did not believe that ‘the mental properties of a thing are to be completely explained by and depend on its physical properties which are in some sense more fundamental’.12 On the other hand, some recent philosophers have argued that physicalism is compatible with the view that certain concepts referring to mental properties are in no way explicable by or derivable from concepts of physical properties.13 Therefore, there remains an open question about whether Spinoza’s comments about the attribute of thought rule out any reading that takes him to be a physicalist. But there is a further objection to the physicalist reading of Spinoza. Physics is not often said to recognise the existence of God’s infinite and eternal essence, expressed through an infinity of attributes. Even Cartesian physics does not recognise this among its objects of study, though it is

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. 4 PACIFIC PHILOSOPHICAL QUARTERLY something upon which many of those objects intimately depend. Thus, besides the attribute of thought, there seems to be something in Spinoza’s metaphysics that may not be readily reconciled with physicalism, namely the infinite essence of God. Again, some scholars have tried to fit this element into a physicalist framework. Curley, for example, identifies God’s essence in Spinoza’s system with the laws of nature.14 Physics certainly seems to recognise laws of nature. Nevertheless, it is unclear that this interpretation, and others like it, would be enough to save Spinoza for physicalism. Suppose that Curley is right and the essence of God for Spinoza does mean the totality of the laws of nature.15 Should we believe that this totality really is the same as the totality of laws of nature recognised by physics? Does it, for instance, make sense in the context of physics to suppose (indeed to find it necessary) that this totality is the cause of itself, or that from the necessity of its nature there must follow everything which can fall under an infinite intellect?16 I am not sure of the answer to this question, and so I must concede that perhaps, although this does not appear to be the most natural reading of his philosophy, Spinoza may qualify as a physicalist. All this, however, might be beside the point. The idea that naturalism is identical with physicalism is highly controversial and has come under severe criticism.17 If ontological naturalism is distinct from physicalism, then even if Spinoza turns out to be a physicalist this will not be sufficient to show that his philosophy has any relevance to contemporary naturalism. A weaker form of ontological naturalism might be proposed, in which nothing is held to exist besides the entities recognized by physics and by other natural sciences. But this opens a number of problematic questions. How do we decide what counts as a natural science? When should we say that a natural science has recognized an entity? Did pre- molecular biology recognize the existence of genes as units of heredity and selection before they were located in DNA? When the possibility remains that an entity posited by a special science might be one day reduced to entities recognized by a more fundamental science, what ontological conclusions should naturalism lead us to draw? Despairing of arriving at any decisive answers to such questions, Barry Stroud has proposed that the only sensible use of the term ‘naturalism’ as an ontological thesis amounts to ‘little more than a slogan on a banner raised to attract the admiration of those who agree that no supernatural agents are at work in the world’.18 A supernatural agent is, he explains, one ‘that somehow stands outside the familiar natural world and whose doings cannot be understood as a part of it’.19 This sense of naturalism seems to line up very nicely with Spinoza’s declared position. Scholars who present Spinoza as a naturalist usually refer to his belief that human thoughts and actions are subject to the same

© 2014 The Author Paciﬁc Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 5 basic laws of nature as those governing non-human things. Della Rocca explains Spinoza’s naturalism in the following terms:

. . . Spinoza’s own view is one according to which . . . human beings and all else operate according to the same laws. Such a uniﬁcation of explanatory principles is the heart of Spinoza’s naturalism about psychology: human psychology is governed by the same principles that govern rocks and tables and dogs.20

This certainly expresses something Spinoza believed, and if holding such a belief is what it means to be a naturalist then Spinoza was undoubtedly a naturalist. The passage usually cited to exemplify Spinoza’s naturalism in this sense is the following:

Most of those who have written about the affects, and men’s way of living, seem to treat, not of natural things, which follow the common laws of Nature, but of things which are outside Nature. Indeed they seem to conceive man in Nature as a dominion within a dominion. For they believe that man disturbs, rather than follows, the order of Nature.

. . . But . . . nothing happens in Nature which can be attributed to any defect in it, for Nature is always the same, and its virtue and power of acting are everywhere one and the same, that is, the laws and rules of Nature, according to which all things happen, and change from one form to another, are always and everywhere the same.21

What he meant by ‘the order of nature’ is made clear in a later passage, which states that ‘the laws and rules of Nature, according to which all things happen, and change from one form to another, are always and everywhere the same’.22 On this definition, Spinoza’s God is not supernatural, since his power is never manifested through violations of the laws of nature.23 Spinoza’s naturalism might then be defined as a rejection of supernaturalism, and this rejection might be identified with the assertion that everything is subject to uniform and universal laws of nature, including human actions and mental events. Perhaps, then, this is all that is meant by contemporary philosophers who take Spinoza’s position to be a form of naturalism, and this is how, if pressed, they would answer if asked how his naturalistic philosophy determines his attitude towards theology. But it is important to observe how few are the commitments of this kind of naturalism. It does not entail physicalism, since things obeying the fundamental laws of nature might be non-physical.24 Nor does the propo- sition that nature’s laws are uniform and universal entail methodological naturalism, since it does not in itself entail that science is the only or the best means of discovering the truth about such laws and the things they govern. And what exactly does ‘standing outside the natural order’ mean? When a theory posits a new kind of entity, is it permissible for the theory to also propose a change to the recognized natural order, so as to accommodate the new member? If not, what should we say of quantum

© 2014 The Author Paciﬁc Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. 6 PACIFIC PHILOSOPHICAL QUARTERLY mechanics, or gravity in the days of Newtonian physics? If so, what posits are actually ruled out, and why? Claiming Spinoza as an ontological naturalist in this sense entails so little that it is difﬁcult to see what use the claim can be in helping us to understand Spinoza’s philosophy either in itself or in its relation to contemporary ways of thinking.

Methodological naturalism

I turn, then, to methodological naturalism: the commitment to natural science as the best or only way to learn the truth about the natural world. This position is described, sometimes pejoratively, as ‘scientism’.25 As Wilfrid Sellars puts it (with deference to Protagoras), naturalism of this kind is the view that ‘science is the measure of all things, of what is that it is, and of what it is not that it is not’.26 Less aphoristically, Alexander Rosenberg describes it as:

. . . the conviction that the methods of science are the only reliable ways to secure knowledge of anything; that science’s description of the world is correct in its fundamentals; and that when ‘complete,’ what science tells us will not be surprisingly different from what it tells us today.27

This view implies that philosophy, insofar as it produces genuine knowledge, must be either a species of natural science or a system that does little more than compare, organize, and draw out the implications of the various natural sciences. Of course, sensibly applying this label to any Early Modern thinker requires one to be liberal about what counts as ‘science’ and what qualiﬁes as being ‘correct in its fundamentals’. The various bundle of theories and explanations of natural phenomena produced by Galileo, Boyle, Descartes, Newton, and others can be classed together as Early Modern science at best only in a very loose sense.28 And the judgment that the description of the world given by this bundle of theories is correct in its fundamentals – insofar as any single general description can be said to be given by them at all – has no hope of being true unless a great deal of weight is given to the clause ‘in its fundamentals’. If we trust our own contemporary science at all we must acknowledge that the world is surprisingly different in any number of important ways from how it appeared to all Early Modern thinkers. But even allowing for all of this – allowing, that is, that there is a body of Early Modern natural science whose description of the world is correct in its fundamentals – it remains unlikely that Spinoza will end up counting as a scientistic naturalist. Although it has been suggested that he presented (to quote a recent textbook) ‘a systematic and coherent

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 7 vision of how the world might look to someone who is willing to suspend belief in revealed religion and take very seriously the claims of the newly emerging natural science’,29 it must be noted again that a great deal of his philosophical conclusions in the Ethics are based on a theory about the necessary existence and omnipotent nature of God. I do not think that many people would regard such a theory to be part of the newly emerging natural science of Spinoza’s age. There is no doubt that various beliefs about God informed the emerging natural sciences of the Early Modern period.30 But if we count those beliefs as part of those sciences then we are placing the activity of rationally reflecting upon the nature of an infinitely perfect being in the same intellectual category as empirical physics, anatomy, and astronomy. A category this broad does not seem to be what naturalists of the scientistic kind mean by ‘science’. Perhaps, however, the attempt to specify any determinate category of scientific thinking is anyway doomed to fail. John Dupré argues that there is no sufficiently unified notion of science to serve as the category required for defining the scientistic version of naturalism.31 Similarly, Penelope Maddy emphasizes the failure of philosophers thus far to have made any successful general analysis of what counts as scientific.32 Both recommend that naturalists give up on scientism and simply dedicate themselves to recognizing the success of, as Dupré puts it, ‘projects that can be directed toward the investigation of the natural world . . . in terms of familiar epistemic virtues such as understanding, explanation, prediction, and control’.33 Nevertheless, even in accepting Dupré’s pluralism about science we must remain implicitly committed to at least some of the familiar con- straints adhered to in demarcating scientific from non-scientific methods. After all, it would be an enormous cosmic coincidence if a group of investigative projects having nothing in common methodologically were all able to attain to the same epistemic virtues. I propose that what they have in common is empiricism. Dupré might resist using the category of empiricism for the same reason he resists using the category of science, namely the lack of any definite criterion for including any given project or method within it. Nevertheless, he would be denying plain facts if he were to resile entirely from the conclusion that those natural sciences whose success is most readily recognized have in common the commitment to testing and modifying their theories, as Rosenberg puts it, ‘by observation, by experiment, by experience, by some sort of sensory awareness of hap- penings that are in one way or another not under our cognitive control’.34 Precisely how deferential one must be to such awareness in shaping one’s theories in order for it to be rightly said that one is subjecting one’s theories to empirical testing is a question to which a determinate answer has been notoriously lacking in the philosophy of science. Nevertheless, I

© 2014 The Author Paciﬁc Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. 8 PACIFIC PHILOSOPHICAL QUARTERLY take it as a consensus view among the informed that, in Peter Godfrey- Smith’s words:

Science works by taking theoretical ideas and trying to ﬁnd ways to expose them to observation. The scientiﬁc strategy is to construe ideas, to embed them in surrounding conceptual frameworks, and to develop them, in such a way that this exposure is possible even in the case of the most general and ambitious hypotheses about the universe.35

In other words, the stipulation that all and only scientific projects pursue empirical methods is not so vulnerable to the looseness of its key terms as to be inapplicable as a general rule of demarcation. Despite Dupré’s concerns, Antonia Lolordo is right to note that ‘the naturalist claim that philosophy is continuous with science is . . . the claim that philosophy has no special methods distinct from the empirical methods of science’.36 I shall therefore, throughout this article, regard methodological naturalism as the view that all reliable knowledge about the world of concrete objects is empirical, meaning it is found through taking theoretical ideas and trying to expose them to observation. Two qualifications are important. First, methodological naturalism on this definition makes no pro- nouncements on how knowledge of non-concrete objects is to be had.37 While this inevitably introduces ambiguities into the position, since the concrete/non-concrete distinction is not always clear, it seems nevertheless prudent. A naturalism that, for example, required all mathematical theories to be exposed to observation before counting as knowledge would be unnecessarily bold. Next, this kind of naturalism allows that scientists may have to work for a long time at developing ideas and embedding them in the relevant conceptual frameworks before the opportunity for observational exposure presents itself. Therefore, areas of proposed knowledge of the concrete world that appear to be purely abstract or conceptual need not be rejected outright by this form of naturalism. Purely conceptual work may be a necessary stage in the process of eventually exposing ideas to observation, and there are unlikely to be any determinate rules about how long it may need to go on. Thus, for example, various Early Modern systems of rational mechanics, based largely on a priori ideas, can be accepted as naturalistic to the extent that they laid important conceptual groundwork for later empirical theories.38 Indeed, parts of modern cosmology, theoretical physics, and perhaps economics have this status today. Both qualifications mean that it will inevitably be somewhat indetermi- nate whether or not a given position is naturalistic. But identifying methodological naturalism with this weak and qualified empiricism seems to be the happy medium between having an implausibly restrictive definition of natural science on one side and denying (with equal implausibility) that there is anything common to the methods of the various sciences, despite

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 9 their sharing in the same epistemic virtues, on the other. Having accepted this characterization of methodological naturalism, one might be able to reply to the above refusal to accept Spinoza as a naturalist. The centrality of God to his philosophy, this reply would go, will not count as anti- naturalistic if his preferred methods for finding out the truth about God were sufficiently empirical. Since Spinoza identified God with nature, and since many thinkers from his time used generally empirical methods for finding out about nature, the possibility of such an interpretation presents itself.39 According to Daniel Dennett, for example (an expert, though not on Spinoza, perhaps on naturalism), the identification of God and nature allowed Spinoza to claim ‘that scientific research was the true path of theology’.40 The relevant question is, then, whether Spinoza’s methods for finding out about God/nature were sufficiently empirical for him to count as a methodological naturalist. The identification of God with nature, also known as φυ´σις, allows for the possibility that the methods of empirical physics are also those of theology. But while many regarded empiricism as the appropriate methodology of physics, was Spinoza among them? Lolordo points out that Early Modern thinkers often identified metaphysics with physics:

. . . not because their metaphysics [was] empirical, but because their physics allow[ed] for a priori speculation. (Think, for instance, of the arguments Descartes [formed] to establish that a vacuum is impossible.)41

Thus, even if we suppose Spinoza to have unified physics and theology, by identifying God and nature, it remains an open question whether he allowed empiricism, even of the weak sort defined above, to be the appropriate methodology for this unified science. There is considerable room for debate about how committed Spinoza was to empiricism, as a variety of articles have shown.42 Spinoza seems to have endorsed empiricism for studying nature in the Tractatus Theologico- Politicus: ‘the method for interpreting nature consists above all in forming a history of nature, from which, as from certain data, we derive the definitions of natural things’.43 Moreover, as David Savan demonstrates, Spinoza was an empiricist ‘[i]n his most successful and important scientific work’.44 Nevertheless, many have cast doubt on Spinoza’s claim to qualify as an empiricist. One of the most recent and thorough discussions is in an article by Eric Schliesser. Among Schliesser’s various arguments against the interpretation of Spinoza as ‘a fellow-travelling mechanical philosopher and proto-scientific naturalist’,45 the following are relevant here. First, Schliesser points out that, according to Spinoza, ‘one cannot deduce particular facts from the laws of motion’.46 Since presumably all we observe are particular facts, if we cannot deduce implications involving

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. 10 PACIFIC PHILOSOPHICAL QUARTERLY particular facts from the laws of motion, it is hard to see how our knowledge of such laws could ever be exposed to observation. Yet since motion appears to be part of the concrete world, methodological naturalism presumably requires knowledge of the laws of motion to be (at least eventually) exposable to observation. On the other hand, as many Newtonian critics of Spinoza pointed out, Spinoza’s theory of motion is strange and probably inconsistent.47 Odd as it sounds, it is possible to understand Spinoza’s ‘infinite mode’ of ‘motion and rest’ as something very different from the kinetic phenomenon we observe in the concrete world – something abstract rather than concrete.48 And thus it may be possible to mount an argument that knowledge of the laws of motion, in Spinoza’s sense, does not constitute knowledge of the concrete world, and thus his anti-empirical attitude towards them does not constitute a violation of naturalism. Next, Schliesser notes that Spinoza was sceptical about the use of mathematics and measurement in the study of nature, which he regarded as piecemeal and relative to the imagination.49 Nothing in my definition of methodological naturalism requires the naturalist to hold any particular attitude towards the use of measurement. Nevertheless, since measurement has proven indispensible in allowing scientists to expose their ideas to observation, Spinoza’s rejection of it implies that if he was a naturalist at all, he was a naturalist of a highly idiosyncratic kind. Finally, Schliesser reminds us that Spinoza recommended that we pursue knowledge of things through their essences, while he was clear that experience cannot teach us anything about the essences of things.50 If knowledge of essences counts as knowledge of the concrete world, then this must constitute a violation of naturalism. The fact that Spinoza calls a thing’s conatus its ‘actual essence’, and draws any number of behavioural conclusions about the actions of (concrete) human beings from facts about the human conatus provides some prima facie evidence that Spinozistic essences are an active and important part of the concrete world, though there is of course much more to be said about this.51 This is, then, another serious challenge to the interpretation of Spinoza as a methodological naturalist. Schliesser also shows that, in contrast with knowledge of things through their essences, Spinoza does not hold high hopes for the knowledge of the natural world that must come from experience.52 This does not constitute a violation of naturalism, however, since one may consistently hold that the most reliable knowledge we can hope to have of the concrete world is empirical in character while admitting that this knowledge is nevertheless very incomplete and unreliable by some absolute standard. The points that Schliesser raises fail to provide decisive grounds for rejecting Spinoza as a methodological naturalist. Too much depends upon how Spinoza’s various metaphysical positions are interpreted. Given the complexity of the latter, this is probably inevitable. In what follows I also

© 2014 The Author Paciﬁc Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 11 do not provide decisive grounds for rejecting the naturalist interpretation of Spinoza. What I propose is that examining the way in which Spinoza positioned himself with respect to other philosophers in his immediate environment tells us something important about his relation to what we call naturalism. While other philosophers who, like him, developed the work of Descartes built a system that was at least amenable to methodological naturalism, Spinoza, we shall see, went determinedly in the opposite direction.

God and a priori knowledge

In 1651, Count Louis Henry of Nassau requested the Dutch universities to give him their opinions of Descartes’ philosophy.53 The universities offered various responses, but the one from Harderwijk University represents the median position. It was, in Paul Dibon’s words, ‘full of respect for [Descartes] the mathematician, tolerant of the physician, irreconcilable to the metaphysician’.54 The authors of the Hardewijk letter informed the Count that: ‘as for [Cartesian] metaphysics, the best people judge it to be a pest to theology and so they condemn it and consider it worthy of suppression’.55 One thing that made Descartes’ metaphysics particularly problematic for traditional theology was that Descartes had made at least one major break with traditional Scholastic metaphysics in his concept of God. Whereas tradition held that God was ‘self-caused’ only in a negative sense that really amounted to his having no cause, Descartes held that God was the cause of himself in a positive sense. An effect of this change was to allow for God’s existence to be proven a priori rather than a posteriori. These terms did not quite mean in the Early Modern period what they mean today. An a priori proof was one that reasoned from cause to effect, while an a posteriori proof was one that reasoned from effect to cause. In the case of proofs of God’s existence, an a priori proof would prove his existence from his cause, whereas an a posteriori proof would prove it from his effects. The distinction was made in its decisive form by St Thomas, as the distinction between a demonstratio propter quid (that is, a priori) and a demonstratio quia (that is, a posteriori):

Demonstration is of two kinds. One is by the cause, and is called propter quid, and this is by what is prior simpliciter. The other is by the effect, and is called a demonstration quia, and this is by those things that are prior for us, as when some effect of something is more manifest to us than its cause and we proceed by the effect to knowledge of the cause.56

St Thomas did not even consider the possibility of an a priori proof of God’s existence, since God was generally held to have no cause.57

© 2014 The Author Paciﬁc Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. 12 PACIFIC PHILOSOPHICAL QUARTERLY Descartes, in presenting God as the cause of himself rather than an uncaused being, opened the possibility of an a priori proof of his existence.58 Although this seems an abstract and technical matter, it was of enormous signiﬁcance for the religious authorities in the Dutch Republic. If God has no cause but is the cause of other things then we can only reason about him a posteriori. This accords with Reformed doctrine, whereby, as for instance ‘The Belgic Confession’ expresses it, God is meant to be known by his effects:

. . . by the creation, preservation, and government of the universe, since that universe is before our eyes like a beautiful book in which all creatures, great and small, are as letters to make us ponder the invisible things of God: his eternal power and his divinity, as the apostle Paul says in Romans 1:20, and more openly by his holy and divine Word, as much as we need in this life, for his glory and for the salvation of his own.59

Note that this effectively asks that our ideas of God be, in Godfrey- Smith’s terms, exposed to observation, namely to what is observed in Scripture and in the book of nature. An a priori proof, by contrast, requires one to begin with direct knowledge of God; it reaches its conclusion by beginning from knowledge of God as a cause and inferring something about God as an effect. Such a proof implies that God as a cause can be directly known prior to his effects. This goes against Reformed doctrine. It also (unless one believes that God can be directly observed) implies that non-empirical knowledge of God is possible. Perhaps because he saw its implications, Descartes did not make explicit the apparent a priori character of his proof. Yet it is revealed through his debate with the Dutch theologian and neo-Scholastic philosopher Johannes Caterus. Caterus responded to a passage in the Meditations in which Descartes had implied that if a thing is caused by itself it must in fact be a being possessing every perfection; that is, God.60 Caterus asked why this must be so, and guessed that Descartes may have had the following argument from Suarez in mind:

Every limitation proceeds from some cause; therefore if something is limited and ﬁnite this is because its cause was either unable or unwilling to endow it with more greatness or perfection; and hence if something derives its existence from itself, and not from some cause [si ergo aliquid a se est, & non a causâ] it is indeed unlimited and inﬁnite.61

For reasons irrelevant to this article, Caterus found this a bad argument. But the phrase I have emphasized shows that Caterus interpreted Descartes’ claim that God is the cause of himself as meaning that really God lacks a cause; he has his existence ‘from himself’ rather than ‘from some cause’. Indeed, Caterus noted, to say that a being is caused by itself

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 13 can mean either that the being is the reason for its own existence, or that its existence has no cause outside of itself, which is to say that really it is an uncaused being.62 The latter, Caterus claimed, is ‘the way in which everyone takes the phrase’.63 In the course of answering Caterus’ objections, Descartes denied this. If a thing has no cause for its existence, he insisted, then it must be the cause of itself not in the merely negative sense of being uncaused but rather in some positive sense.64 Caterus had interpreted Descartes wrongly when he assumed that by ‘self-caused’ he meant only ‘uncaused’, as ‘everyone takes the phrase’. As Étienne Gilson points out, although Caterus’ way of interpreting ‘self-caused’ was standard in the Scholastic context, ‘the pecu- liarity of the Cartesian position is to admit that God, precisely because he is infinite, in some way behaves towards himself in the manner of a cause’.65 Descartes had in fact reasoned from God-as-a-cause’s ‘supera- bundance of power [exuperantiam potestatis]’ to God-as-an-effect’s necessary existence.66 Nothing can stop God’s superabundant power from causing his own existence; thus he exists necessarily. Whether this proof was properly a priori or not is perhaps disputable. But Descartes certainly opened the possibility of an a priori proof by changing the conception of God from that of an uncaused being to that of a self-caused being, for the reason that one obviously cannot reason from the cause of an uncaused thing, whereas this is not the case for a self-caused thing. As we shall see, Spinoza took this possibility up in earnest. Because of the apparent threat to traditional theology, most Cartesian professors in the Dutch universities tried their best to play down the importance of metaphysics in the Cartesian system. For example, the Cartesian professor of physics at Leiden, Johannes De Raey, ‘entirely dispense[d] with Descartes’ metaphysics. He [did] not mention systematic doubt, or the cogito, nor [did] he attempt to prove the existence of God’.67 Yet Descartes’ metaphysics seems to have played a crucial role in justifying his philosophical method.68 God’s necessary existence was meant to guarantee the truth of our clear and distinct ideas, such as are used in philosophy.69 In fact, Descartes had stated unambiguously that ‘all the treasures of wisdom and the sciences lie hidden . . . in the true God’.70 Besides this, Cartesian physics – the part of Cartesian philosophy that professors like De Raey hoped to promote – drew upon elements of Cartesian metaphysics, especially some of his thoughts about God.71 Descartes famously suggested that metaphysics was the root of the tree of philosophy (of which physics was the trunk).72 Perhaps De Raey hoped that the foundations Descartes sought to provide with his metaphysics could also be provided by orthodox theology, or at least by a system of metaphysics less prone to conflict with orthodoxy. Effectively, however, De Raey’s position left Cartesian physics without any metaphysical foundation. It is worth noting that while Descartes had

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. 14 PACIFIC PHILOSOPHICAL QUARTERLY intended his physics to be published after the Meditations,73 in the Dutch context Henricus Regius had ruined this plan by publishing several dispu- tations on Cartesian physics in 1640–1.74 The idea that Cartesian physics was somehow independently justified, rather than grounded in metaphysics, was perhaps more natural in the Dutch universities than elsewhere for this reason. But it presents a puzzle. De Raey believed that physics, as part of philosophy, depended only on the ideas of the intellect and not on the senses. Natural philosophy ‘is, and should be, absolute and intrinsic, and known solely by the intellect’.75 He distinguished between observation- based ‘natural history’ and the ‘true science’ of nature, ‘by which we can have knowledge of hidden things according to the intellect’.76 The puzzle is why we should trust that our intellect represents things as they truly are in the world.77 For Descartes, the answer appeared to involve God. While clear and distinct ideas can perhaps be known to be true without knowledge of God, knowing their applicability to the concrete world seems to depend on the latter.78 But this again suggests that we must have true knowledge of God before we have knowledge of nature, as indeed the third Meditation claimed: ‘I must examine whether there is a God, and, if there is, whether he can be a deceiver. For if I do not know this, it seems that I can never be quite certain about anything else’.79 Again this introduces the heretical suggestion that God can be known directly rather than through his effects. Yet De Raey and his fellow Cartesians had argued, largely for political reasons, that philosophy and theology (the latter included all knowledge of God) are utterly independent of each other.80 For him, the less con- nected philosophy is to theology, ‘the more excellent and true it is’.81 Knowledge of God and his non-deceiving character cannot be used to guarantee ideas of the intellect used in physics. A disputation defended under De Raey in 1668, argued that physics should be regarded as ‘the science of the visible world, for the task of physics is none other than the explanation of the sensible world through intelligible causes’.82 But neither De Raey nor the disputant explained what could justify the application of intelligible causes to the sensible world if not the guarantee of applicability delivered by God. A system of physics that claims no explicit justification for its key ideas at all must appear inferior to one that claims its justification in observed data. This appears to be at least one of the reasons why Cartesian physics gave way to empirically-based – mostly Newtonian – systems in the Dutch Republic earlier than anywhere else.83 Theo Verbeek argues that the specific version of Cartesian physics proposed by De Raey and his associates prepared the ground for the early acceptance of Netwonian physics in Leiden.84 In the 18th century, Pieter van Musschenbroek, one of these early followers of Newton, denied that we have any ‘innate ideas either of bodies or of their properties or of their actions on one another’. Instead, he

© 2014 The Author Paciﬁc Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 15 argued, ‘we must investigate and learn everything by experiment and observations, and then form ideas of it for ourselves’.85 It is hard to see how a Cartesian could defend the application of innate intellectual ideas to sensible data in the face of this attack, without resorting to Descartes’ metaphysical notions. Thus by cutting off Cartesian physics from its metaphysical roots, Dutch Cartesians like De Raey allowed it to be easily washed away in the rising tide of empiricism. Spinoza, by contrast, emphasised precisely the elements in Cartesian philosophy that the Dutch Cartesians wanted to play down. To his pres- entation of Cartesian philosophy, published in 1663, he appended a set of Metaphysical Thoughts, which made Cartesianism into a novel system of metaphysics containing several radical theological ideas.86 In the Short Treatise, he laid great emphasis on the availability of an a priori proof for the existence of God due to the Cartesian idea of God as a self-caused rather than uncaused being:

. . . we can prove both a priori and a posteriori that God exists. Better, indeed, a priori. For things which are proved in the latter way [a posteriori] must be proved through their external causes, which is a manifest imperfection in them, inasmuch as they cannot make themselves known through themselves, but only through external causes. God, however, who is the ﬁrst cause of all things, and also the cause of himself [causa sui], makes himself known through himself. Hence one need not attach much importance to the saying of Thomas Aquinas, namely, that God could not be proved a priori because he forsooth has no cause.87

We have seen that proving God’s existence a priori implies that we can know him directly, rather than through his observable effects. Moreover, it is very unlikely that even Spinoza’s God-as-nature can be known by direct observation. Surely we have no sensory experience of nature as a whole, or in itself, independently of our sensory experiences of particular natural things. 88 In fact Spinoza even rejected the standard view that God could be known through his effects: in the Short Treatise, he argued that ‘[i]t is impossible to get to know God through something else’.89 He thus fully embraced the kind of innate, non-empirical knowledge of God that De Raey wanted to purge from Cartesianism. Yet we have seen that it was precisely this purge that made De Raey’s version of Cartesianism vulnerable to empiricist critiques by Newtonians and others. Without Descartes’ metaphysical foundations, it was left with no way of justifying its dependence on innate ideas.90 Spinoza held onto the foundations, thus sustaining an alternative to empiricism unavailable to De Raey. This is not to say that Spinoza’s system was not also open to criticisms by the new Newtonian empiricists when they arrived.91 The claim is not that he provided a wholly successful alternative to empiricism; it is that, unlike De Raey, he held onto the metaphysical foundations that could have provided the only grounding for such an alternative. He seems therefore to be a very bad candidate for the title of methodological

© 2014 The Author Paciﬁc Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. 16 PACIFIC PHILOSOPHICAL QUARTERLY naturalist. De Raey and other Cartesians could be regarded as proto- naturalists to the extent that they left no space for non-empiricist metaphysical standards of justiﬁcation in physics, in effect leaving room for the development of empiricist standards. The same cannot be said of Spinoza.

Conclusion

The claim that Spinoza was an ontological naturalist, we have seen, is false unless the term is drained of all useful content. The claim that he was a methodological naturalist, we now see, is, if not false, then at least extremely misleading with respect to his historical position. As a tolerable simpliﬁcation, I recommend we say that he was not a naturalist.

Alexander Douglas Institute of Philosophy and King’s College, London

NOTES

Abbreviations used are as follows: (AT) René Descartes, Oeuvres de Descartes, C. Adam and P. Tannery, eds. Paris: Vrin, 1974. (CSM) The Philosophical Writings of Descartes, J. Cottingham, R. Stoothoff and D. Murdoch, eds, 3 vols. Cambridge: Cambridge University Press, 1985. (G) Benedictus de Spinoza, Opera, C. Gebhardt, ed. Heidelberg: Carl Winters, 1924. 1 A few examples: Bennett, 1984, §9.10; Della Rocca, 2007, pp. 852ff; Garrett, 2008, pp. 18ff. Jonathan Israel also claims that Spinoza’s philosophy was naturalistic (for example: Israel, 2006, p. 46 and Israel, 2003, p. 197). But it is unclear whether Israel intends the word ‘naturalistic’ here to have its current technical sense rather than the sense it would have had to Early Modern thinkers (see, for example, Leibniz, 1989b). 2 Ritchie, 2008, p. 1. 3 By contrast, Samuel Alexander’s 1933 lecture on Spinoza observed that ‘to condemn a man’s philosophy it is only needful nowadays to call it naturalism’ (Alexander, 1933, p. 7). 4 Paul Draper provides a brief discussion of various kinds of naturalism, giving specific definitions and problems with them: Draper, 2005. Mario de Caro and David Macarthur give a good historical appraisal of naturalism in recent philosophy: De Caro and Macarthur, 2004. David Papineau and Penelope Maddy both argue, though in different ways, that it is more important to characterise the naturalistic attitude than it is to give a rigorous formal definition of the naturalist position: Maddy, 2007; Papineau, 2009, 1993. 5 De Caro and Macarthur, 2004, p. 5. 6 De Caro and Macarthur, 2004, p. 5, quoting Armstrong, 1980, p. 156. See also Montero, 2005. 7 See, e.g., Principles II.3–4, AT VIIIA.42/CSM I.224–5 (Descartes, 1974, 1985). 8 See Ethics I.P15. 9 Michael Della Rocca argues against a physicalist interpretation of Spinoza on these grounds: Della Rocca, 2008, p. 103. He seems here to be taking physicalism in something like Armstrong’s sense. But Galen Strawson opposes Armstrong’s definition of physicalism (though he does not name Armstrong specifically). For him, real physicalism recognises the existence of conscious experience as a kind of stuff that is irreducible to any entities

© 2014 The Author Pacific Philosophical Quarterly © 2014 University of Southern California and John Wiley & Sons Ltd. WAS SPINOZA A NATURALIST? 17 that modern physics recognises as being among its objects of study. Armstrong’s position, according to Strawson, is not real physicalism but rather ‘physicSalism’ – a view he attacks mercilessly. See Strawson, 1994, 2006. 10 See Ethics II.P13.S; Curley, 1988, II.10. 11 Place, 1956; Smart, 1959. 12 Della Rocca, 2008, p. 103. See also Della Rocca, 1996. 13 Papineau, 2002, §2 and §5.4. 14 Curley, 1988, esp I.13; Curley, 1969, ch. 2. 15 This is an odd reading for reasons besides those I have given; see Melamed, 2009, pp. 24–27. 16 Ethics, I.Def1, P7, P11, P16. Leibniz found the latter view to follow from what Descartes took to be a consequence of the laws of physics, namely ‘that matter successively accepts all shapes’. Interestingly enough, Leibniz goes on: ‘Spinoza begins where Descartes leaves off: in naturalism’ (Leibniz, 1989a, p. 277). Note, however, that ‘naturalism’ for Leibniz meant something different from what it means in the contemporary context – see note 1. 17 An accessible argument for ‘naturalism without physicalism’ can be found in Ritchie, 2008, ch. 6. Critical studies of the physicalist versions of naturalism can be found in Gillett and Loewer, 2001. See also Robinson, 1993. David Chalmers develops a form of ‘naturalistic dualism’ in Chalmers, 1996, ch. 4. 18 Stroud, 2004, p. 35. 19 Stroud, 2004, p. 23. 20 Della Rocca, 2007, p. 852. 21 Ethics III.Pref., G, II.137–8. Translation: Benedict de Spinoza, (Spinoza, 1985). 22 Ethics III.Pref., II/138. 23 See Ethics I.P33 (and its scholia) and Tractatus Theologico-Politicus chs.4 and 6. (The translation I use is Edwin Curley’s (Spinoza, 1670).) 24 Perhaps the most prominent living non-physicalist naturalist is David Chalmers – see the chapter called ‘Naturalistic Dualism’ in Chalmers, 1996, ch. 4. 25 Alexander Rosenberg attempts to reclaim the label as a term of praise, or at least of personal allegiance: Rosenberg, 2011, pp. 6–7. 26 Sellars, 1963, p. 173. 27 Rosenberg, 2011, pp. 6–7. 28 Margaret Osler defends a strong claim to the effect that no Early Modern intellectual project bears a particularly close resemblance to what we recognise today as natural science: Osler, 2010. For some criticism of this argument see Douglas, 2012. 29 Cook, 2007, p. 7. 30 It is worth bearing in mind that this statement is still within the above qualifier ‘. . . if we allow that there is a body of Early Modern science’. Since this is doubtful, the question of whether or not theology should be counted within that body may well appear misbegotten; I am entertaining it here only for the sake of argument. For some discussion of the relation- ship between Christianity, or Protestantism particularly, and the development of modern science, see Drees, 1996; Harrison, 1998 and 2007. Two books that argue that the latter depended intimately upon the former are Hooykaas, 1973 and Whitehead, 1927. Some discussion of the place of God in Early Modern scientific explanations can also be found in Lolordo, 2011. 31 Dupré, 2004, p. 55. 32 Maddy, 2007, p. 15. For a defence of the unity of the sciences idea, however, see Drees, 1996, pp. 13–17 and passim. 33 Dupré, 2004, p. 55. 34 Rosenberg, 1981, p. 13.

35 Godfrey-Smith, 2003, p. 161. 36 Lolordo, 2011, p. 655. 37 I avoid saying ‘abstract’, just in case there might be reasons to believe in non-concrete objects that are not abstract. 38 On this see, for instance Maglo, 2003. 39 See, for instance, Ethics IV.Pref. 40 Dennett, 1995, p. 185. 41 Lolordo, 2011, p. 655. Lolordo refers to the Principles of Philosophy, II.16–18 (AT VIIIA.49–50). 42 Curley, 1973; Israel, 2003 and 2001, ch. 14; Maull, 1986; McShea, 1968; Savan, 1986; Verbeek, 2008a and b. 43 ...methodus interpretandi naturam in hoc potissimum consistit, in concinnanda scilicet historia naturae, ex qua, utpote ex certis datis, rerum naturalium deﬁnitiones concludimus (G III.98). 44 Savan, 1986, p. 99. 45 Schliesser, forthcoming 2014, p. 1. All page numbers refer to an unpublished draft of this article. 46 Schliesser, 2014, p. 8. 47 Schliesser, 2012 and 2014, §3A. 48 See Letter 64, G IV.278. 49 Schliesser, 2014, §2. See also Savan, 1986, pp. 101–104; Verbeek, 2008a and b. 50 Schliesser, 2014, §3. See Spinoza’s Letter 10, to Simon de Vries, G IV.47. Again Verbeek discusses the same issue: Verbeek, 2008a and b. 51 See Ethics III.P7 and the following propositions. 52 Schliesser, 2014, §1B and C. See also Maull, 1986; Savan, 1986, pp. 109ff; Verbeek, 2008a and b. 53 Verbeek, 1992, pp. 82–90. 54 Dibon, 1954, p. 191. 55 Letter quoted by Josef Bohatec, in Bohatec, 1912, pp. 153–155. 56 . . . duplex est demonstratio. Una quae est per causam, et dicitur propter quid, et haec est per priora simpliciter. Alia est per effectum, et dicitur demonstratio quia, et haec est per ea quae sunt priora quoad nos, cum enim effectus aliquis nobis est manifestior quam sua causa, per effectum procedimus ad cognitionem causae (Aquinas, 1894, 1.2.2). The distinction between what is ‘prior simpliciter’ and what is ‘prior to us’ matches the distinction between those things ‘better known to us’ and those ‘better known by nature’ (γνωριμωτε´ρων φυ´σει) found in various places in Aristotle, for example in the Physics (184a116–18) and various places in the Posterior Analytics (Aristotle, 1831). See also Suarez, 1965, III.3.6. The relevance of this material to Spinoza is discussed in detail in Verbeek, 2008a and 2005. 57 Aquinas, 1894, 1.2.2. 58 One could say Descartes reopened it, since St. Anselm’s proof could be seen as being a priori. St. Thomas rejected Anselm’s proof: Aquinas, 1894, 1.2.1. Descartes argued that Thomas’ criticisms did not apply to him in the ﬁfth Reply to the Meditations: AT VII.100/ CSM II.82. See also Nolan, 2011. 59 ‘The Belgic Confession,’ in The Creeds of Christendom: The Evangelical Protestant Creeds (2007, Article 2). 60 AT VII.50/CSM II.34. 61 AT VII.95/CSM II.69. My emphasis. I have not been able to track down the source of this quotation or paraphrase. 62 First Objection, AT VII.95–96/CSM II.68–9. 63 AT VII.95/CSM II.68.

64 AT VII.112/CSM II.80. 65 Gilson, 1921, pp. 225–226, n.223. 66 AT VII.112/CSM II.80. 67 Verbeek, 1992, pp. 88, 72. De Raey defended Descartes’ metaphysics in an appendix to a later edition of one of his books, but not by going into great detail about it: ‘Pro vera metaphysica, quae de principiis humanae cognitionis tractat’ (de Raei, 1677, pp. 412– 439). 68 Some scholars disagree at least with the view that Descartes’ metaphysics plays a role in justifying his method in physics: Buchdahl, 1969; Caton, 1973; Clarke, 1982; Hatfield, 1985, 1988. Even Hatfield, however, agrees that Descartes’ metaphysic play an indispensible role in overcoming possible theological objections to his physics: Hatfield, 1993. 69 See the fourth Meditation. 70 AT VII.53/CSM II.37 71 Garber, 1992; Gaukroger, 2002; Hatfield, 1979. 72 Letter to Clerselier, AT IXB.14/CSM I.186. 73 Again, see the letter to Mersenne, 28 January 1641, AT III.298/CSM III.173. 74 See Rheno-Trajectina Academia, Testimonium Academiæ Ultrajectinæ, et narratio historica, quâ defensæ, quâ exterminatæ novæ philosophiæ (Academia Rheno-Trajectina, 1643); Israel, 1995; Ruestow, 1973; Verbeek, 1992. 75 ‘Disputatio Philosophico; Specimen exhibens Modestiae et Prudentiae in Philosophando’ (1687) in Joannes de Raei, Cogitata de Interpretatione (Raei, 1692, p. 652). 76 De Sapientia Veterum (1669) in Raei, 1692, p. 382. 77 Descartes claims, in the Principles, to need no ideas for his physics besides those of geometry and pure mathematics: II.64, AT VIIIA.78/CSM I.247. 78 On this see Carriero, 1987. But see footnote 71. 79 AT VII.36/CSM II.25. 80 On this see Douglas, n.d.; Thijssen-Schoute, 1989; Verbeek, 1992, 1993, 1995. 81 Disputatio Philosophico; Specimen exhibens Modestiae et Prudentiae in Philosophando (1687) in Raei, 1692, p. 653. 82 de Reus, 1688, I. 83 The history of this transition is recounted in Ruestow, 1973. See also Jorink, 2009; Schliesser, 2012. 84 Verbeek, 2003, pp. 174fn., 179. 85 De Pater, 1975, p. 323. 86 See Douglas, n.d. 87 Spinoza, 2002, I.i, 40. 88 A useful discussion of this general topic is found in R.G. Collingwood’s essay ‘Faith and Reason’, a pamphlet in the ‘Affirmation Series’, (Collingwood, 1928/1968, pp. 122–47). 89 Spinoza, 2002, II.xxiv, 98. 90 It seems as if a similar thing happened in France; see Clarke, 1989. 91 Schliesser, 2012.

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