Journal of the History of Philosophy

Descartes's Case for Dualism MARLEEN ROZEMOND ONE OF DESCARTES'S MOST LASTING CONTRIBUTIONS to philosophy is his wellknown argument for dualism. This argument continues to attract attention not just from historians of philosophy, but from the philosophical community at large. It is generally believed that the modal claim that mind can exist unextended or without body is central to this argument. According to some, Descartes's dualism simply consists in the separability of mind and body. Others hold that it does not consist in this modal claim, but believe that this claim is central to his argument for dualism. I wish to propose a radically different interpretation. It is true that Descartes was concerned with the possibility of mind existing unextended and without body. But I will contend that this idea is not central to the argument. Descartes's dualism does not consist in this modal nodon, nor is this notion fundamental to his argument. The most prominent statement of the argument is to be found in the Meditations. In this work the argument has two focal points, one in the Second and the other in the Sixth Meditation. As a result of the skeptical arguments of the First Meditation, Descartes doubts in the Second Meditation that there are any bodies. Nevertheless he is certain that he exists and thinks. Using these observations Descartes argues that he has a clear and distinct perception of the mind as a thinking, unextended thing. In the Sixth Meditation he uses this perception to show thai the mind is an incorporeal substance, really distinct from the body. This is the conclusion of what I will call the Real Distinction Argument.' What exactly does Descartes think he accomplishes in his discus- ' What I call the Real Distinction Argument is not, however, Descartes's only argument for dualism. Also in the Meditations Descartes argues that mind and body are distinct on the ground that the mind is indivisible, while body is divisible (AT VII 85-86 ). In the Discourseand other places Descartes lists various human capacities in favor of the idea that the human being is not just a body (AT VI 55-60). References to Descartes are specified as follows. I always provide the reference to Charles Adam and Paul Tannery, OeuvresdeDescartes(Paris: Vrin, a964- 1978), using the abbreviation AT and specifiying volume and page numbers. Translations can be found in John Cottingham, Robert Stoothoff and Dugald Murdoch, trans., The Philosophical Writings of Descartes(New York: Cambridge University Press, 1985, 2 volumes), which provides the AT page 09] 3~ JOURNAL OF THE HISTORY OF PHILOSOPHY 33:~ JANUARY 1995 sion of the mind in the Second Meditation, and how does he think he can get from the results of the Second Meditation to the real distinction of mind and body in the Sixth Meditation? The argument is often criticized on the ground that the claims about the mind that Descartes is entitled to in the Second Meditation are insufficient to lead to dualism. My interpretation of the Real Distinction Argument provides answers to these questions. The argument, I will contend, crucially relies on various aspects of Descartes's conception of substance. Descartes held that each substance has a principal attribute, a property which constitutes its nature or essence.' Other properties of the substance are its modes. The modes of a substance presuppose this attribute: they cannot exist without it, nor be clearly and distinctly understood without it. These aspects of Descartes's conception of substance lead to the real distinction of mind and body in the following way. In the Second Meditation we find we can clearly and distinctly understand a thinking thing while doubting that there are bodies, and while ascribing no corporeal properties to the mind. This leads to the conclusion that thought is not a mode of body, but a principal attribute (sections 2-3). Furthermore, extension is the principal attribute of body (section 4)- Finally the argument relies on the idea that a substance has only one principal attribute (section 5). It follows then that mind and body are different substances, and really distinct . After completing my account of the argument I consider its relationship to the idea that mind and...