Looking at the Surface of the Mind: Descartes on Visual Sensory Perception DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy 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 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 together, and the roadmap for discovery is found in Descartes’ theory of sensory perception. Descartes’ views 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. 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 object, 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 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. 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 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. My arguments 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 Nicolas Malebranche, in part, to locate the “wedge” of his theory of sensory perception in God. iii Light is the source of life. To my mother. iv Acknowledgments Descartes might have us believe that philosophy is best done in solitude. This has not been my experience, though. This dissertation would be little more than a collection of wandering thoughts were it not for the sustained intellectual, 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 history 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 set out to write a dissertation in the history of philosophy if not for certain philosophers in my own history, however. I extend gratitude to Walter Ott for sparking my interest in Nicolas Malebranche and early modern Cartesianism during my v time at Virginia Tech. I also thank Christopher Martin for his many contributions to my undergraduate education 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 family. 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 being my family away from home. I am especially grateful to Jerilyn Tinio for her knowledge and enthusiasm about all things pineal gland. 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 memory. Uncle Ramon, you were right, Aristotle was the only philosopher 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 love makes life eternal. I do not have biological siblings, but I nonetheless have a brother in blood and origin. Anthony Castillo, you are my brother, and will 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 nothing 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 choice was—and continues to be—the reason 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 suffering 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.