Matter and Consciousness

2 The Ontological Problem (the Mind–Body Problem)

2 The Ontological Problem (the Mind–Body Problem) What is the real nature of mental states and processes? In what medium do they take place, and how are they related to the physical world? Will my consciousness survive the disintegration of my physical body? Or will it disappear forever as my brain ceases to function? Is it possible that a purely physical system such as a computer could be constructed so as to enjoy real conscious intelligence? Where do minds come from? What are they? These are some of the questions we shall confront in this chapter. Which answer we should give to them depends on which theory of mind proves to be the most reasonable theory on the evidence, to have the greatest explanatory power, predictive power, coherence, and simplicity. Let us examine the available theories, and the considerations that weigh for and against each. 1 Dualism The dualistic approach to mind encompasses several quite different theories, but they are all agreed that the essential nature of conscious intelligence resides in something nonphysical, in 12 Chapter 2 something forever beyond the scope of sciences like physics, neurophysiology, and computer science. Dualism is not the most widely held view in the current philosophical and scienti fic community, but it is the most common theory of mind in the public at large, it is deeply entrenched in most of the world’s popular religions, and it has been the dominant theory of mind for most of Western history. It is thus an appropriate place to begin our discussion. Substance Dualism The distinguishing claim of this view is that each mind is a distinct nonphysical thing, an individual ‘package’ of nonphysical substance, whose identity is independent of any physical body to which it may be temporarily ‘attached’. Mental states and activities derive their special character, on this view, from their being states and activities of this unique, nonphysical kind of substance. This leaves us wanting to ask for something more in the way of a positive characterization of this proposed mind-stuff. It is a frequent complaint with the substance dualist’s approach that his characterization of it is so far almost entirely negative. We are told what it isn’t, but not what it is. This need not be a fatal flaw, however, since we no doubt have much to learn about the underlying nature of mind, and perhaps the deficit here can eventually be made good. On this score, the philosopher René Descartes (1596–1650) has done as much as anyone to provide a positive account of the nature of the proposed mind-stuff, and his views are worthy of examination. Descartes theorized that reality divides into two basic kinds of substance. The first is ordinary physical matter, and the essential feature of this kind of substance was said to be that it is The Ontological Problem 13 extended in space: any instance of it has length, breadth, and height, and occupies a determinate position in space. He dubbed it res extensa (extended substance). Descartes did not attempt to play down the importance of this kind of matter. On the contrary, he was one of the most imaginative physicists of his time, and he was an enthusiastic advocate of what was then called “the mechanical philosophy.” But there was one isolated corner of reality he thought could not be accounted for in terms of the mechanics of matter: the conscious reason of humankind. This was his motive for proposing a second and radically different kind of substance, a substance that has no spatial extension or spatial position whatever, a substance whose essential feature is the activity of thinking. He dubbed this second kind of matter res cogitans (thinking substance ). This view is known as Cartesian dualism. As Descartes saw it, the real you is not your material body, but rather a nonspatial thinking substance, an individual unit of mind-stuff quite distinct from your material body. This nonphysical mind is in systematic causal interaction with your body, to be sure. The physical state of your body’s sense organs, for example, causes visual/auditory/tactile experiences in your mind. And the desires and decisions of your nonphysical mind cause your body to behave in purposeful ways. Its two-way causal connections to your mind are what make your particular body yours, and not someone else’s. The main reasons offered in support of this view were straightforward...