1 I give permission for public access to my thesis and for any copying to be done at the discretion of the archives librarian and/or the College librarian. _______________________ _______________________ Signature Date 2 Preserving “Simple Suppositions” A Humean Response to Reductionism about Personal Identity A Thesis Submitted to the Philosophy Department Faculty of Mount Holyoke College in Partial Fulfillment of the Requirements for The Degree of Bachelors of Arts with Honors. Summa cum laude. Lindsay Crawford Mount Holyoke College 2005 3 Acknowledgements I am honored to thank formally my primary thesis advisor, Jay Garfield of Smith College, for his confidence in my work, the breadth of his wisdom and vision, and his untiring commitment to seeing this project reach fruition from its most embryonic stages. I am indebted to Jay for his guidance, patience, and his thoughtful feedback, including both his fairest praise and harshest criticism. Without Jay, I would not have a thesis to defend. Additionally, I thank my second thesis advisor, James Harold, for his dedication and close attention to my project, as well as his helpful comments and advice. I also thank the University of Colorado-Boulder philosophy faculty and graduate students, who introduced me to Derek Parfit’s “Reasons and Persons” and whose help and insight provided a strong foundation for this work. Additionally, I thank those professors whose influences on my intellectual development have been invaluable: Lee Bowie, Stiv Fleishman, Sam Mitchell, Ann Murphy, and William Quillian. Finally, I thank my colleagues, Constance Kassor, Kathryn Lindeman, Carolyn O’Mara, and Katia Vavova. These women have set remarkable examples of tireless academic rigor and commitment to philosophy, which have profoundly motivated and shaped the nature of my philosophical interests and pursuits. I am unspeakably fortunate for having found such a strong community of dedicated philosophers. This work is dedicated to Henry E. Crawford. 4 Contents CHAPTER ONE: PERSONAL IDENTITY AND REDUCTIONISM........................... 5 “My Division”................................................................................................... 6 Parfit’s Reductionist Thesis............................................................................ 12 Conclusion ...................................................................................................... 16 CHAPTER TWO: THE REDUCTIONIST ACCOUNT OF AGENCY....................... 20 Common Sense Egoism .................................................................................. 24 Reductionism and the Unity of Consciousness............................................... 32 IMPLICATIONS OF THE REDUCTIONIST VIEW .................................................... 36 HOW REDUCTIONISM BEARS ON PRUDENTIAL CONCERN................................. 39 BEYOND PRUDENTIAL CONCERN ..................................................................... 42 AGENCY FROM THE REDUCTIONIST STANDPOINT............................................. 44 Kant’s Two Perspectives View....................................................................... 46 Korsgaard on the Unity of Agency ................................................................. 49 An Assessment of Korsgaard’s Strategy ........................................................ 56 CHAPTER THREE: HUME’S FICTIONALISM ................................................... 61 Hume’s Book One: A “Bundle” Theory of Persons ....................................... 64 Hume’s Book Two: Persons and their Passions ............................................. 82 Hume’s Second Thoughts............................................................................... 90 Conclusion ...................................................................................................... 92 CHAPTER FOUR: REDUCTIONISM AND MORALITY ....................................... 94 Rejecting the Unity of Agency ....................................................................... 99 COMMITMENTS AND THE LANGUAGE OF SUCCESSIVE SELVES......................... 99 COMMITMENTS AND THE LAW: HONORING PRIOR DIRECTIVES ..................... 107 DESERT .......................................................................................................... 113 Rejecting the Separateness of Persons.......................................................... 128 DISTRIBUTIVE JUSTICE................................................................................... 128 Conclusion .................................................................................................... 134 CHAPTER FIVE: FICTIONALISM AND MINIMALISM..................................... 139 The Supervenience Structure of Reductionism ............................................ 140 Minimalism................................................................................................... 142 THE MINIMALIST DEFENSE OF NON-DERIVATIVE CONCERN ......................... 144 Fictionalism on the Justificatory Status of Person-directed Beliefs ............. 149 Conclusion .................................................................................................... 154 BIBLIOGRAPHY ............................................................................................. 157 5 Chapter One: Personal Identity and Reductionism Thought experiments deriving from recent developments in neuroscience have come to dominate debates about personal identity. One response to these thought experiments, which are often rooted in wildly counterfactual scenarios, is to argue that they are simply so implausible that they are essentially uninformative. Quine writes dismissively, “to seek what is ‘logically required’ for sameness of persons under unprecedented circumstances is to suggest that words have some logical force beyond what our past needs have invested them with.”1 Here Quine is suggesting that our concept of a person is one that can be explained sufficiently by appealing to our ordinary uses of the concept; to act as if the concept of a person survived in hypothetical cases where we could isolate these ordinary uses would be to misuse the concept entirely and render it unintelligible. Some, however, argue that these thought experiments are sufficiently plausible such that our intuitive responses to them should be taken seriously. The idea is that by conceptually isolating certain features of our ordinary concept of persons, we can come to understand what the crucial feature is that bases the concept of a person. And deciding what this crucial feature is depends on our intuitive responses to the work these thought experiments do in conceptually isolating certain features. 1 Quine (1972): 490. 6 Parfit2 defends this view, and such thought experiments motivate his reductionist analysis of persons. His reductionist analysis has two primary components: a metaphysical view of what matters about persons, and a moral view of what matters about persons. Parfit takes the latter view to be a necessary consequent of the former. So we must note on the outset that there are two distinct claims being made, united by the implicit conditional that if our metaphysical view is correct, it ought to structure our moral view. In what follows, I will first introduce “My Division,” the primary thought experiment that Parfit uses to introduce the problem of personal identity.3 I will examine in this chapter what Parfit believes to be the problem of personal identity, and how this problem motivates his reductionist claims. I will then explicate Parfit’s metaphysical picture, and show the way in which this picture is supposed to bring us to a certain view of persons. Parfit holds that this view of persons structures further claims about agency and morality, which will be unpacked in the coming chapters. “My Division” Suppose I have been involved in a near fatal accident, from which I emerge with a badly degenerated body, and the right hemisphere of my brain is rendered irreversibly damaged and utterly useless. Because my body is 2 Parfit (1984) 7 degenerating, my heart will eventually stop, and I will eventually lose everything, including my fully functional left hemisphere. The only way I can survive is by transplanting my left hemisphere into the de-brained and receptive body of another person. Let’s call the person who receives my fully functional left hemisphere “Lefty.” On many accounts of personal identity, Lefty would be my former self. This is because, in the absence of any other options, Lefty can preserve what is believed to be most central about my identity – my brain. It should first be noted that what gives this thought experiment force is that it has been proven that the two upper hemispheres of the brain can be disconnected, yet still be fully functional. Indeed, there exist cases where people must remove, or are born without, the corpus collosum that connects the left and right hemispheres of the brain.4 Parfit dismisses the objection that because we have, as of yet, not been able to transplant one hemisphere of a brain into a de-brained body, that the “My Division” case is impossible and therefore ought not to be entertained. Its impossibility is merely technical. What motivates this thought experiment is the fact that a person’s consciousness can be divided into independent streams. This, Parfit says, has been proven by advances in neuroscience.5 Only if this claim were false would we have a real objection to the use of this 3 Parfit (1984): 255. 4 Parfit (1984): 254. 5 Ibid.