Answering Some Objections to Substance Dualism #1
1. It is plain that consciousness depends very sensitively on the physical state of the brain. Twiddling this or that neuron can induce memories, qualia, feelings, behavior, etc. Why is this the case, if our minds aren't simply something the brain is doing? Consciousness can be wiped out by tiny brain lesions, and personalities can be fundamentally altered by damage to the brain.
2. How is the mind connected to the brain? How is the causal linkage of a nonmaterial entity to the macroscopic physical world achieved, without violating all sorts of conservation principles?
3. Where does the mind arrive from? At what point in embryonic development does the "ensoulment" take place? At what point in our evolutionary history? And if you have an answer for that, why then?
All of these problems seem more tractable from a physicalist point of view, and as I have said, I have heard no offers of any explanations at all from the dualist camp.
Since blogposts are supposed to be short, I will answer only the first objection in this post.
Ad 1. There are certain data that no one will dispute, whether materialist, dualist, or idealist. Among these data are the various correlations to which Malcolm is referring: stimulate this portion of the visual cortex in such and such a way and the subject experiences phenomenal blue, etc. Intelligent dualists have always been aware of such basic facts as that drinking alcohol alters the quality of one's qualia, that a blow to the head can cause unconsciousness, and the like. It is important to realize that dualists are not in the business of denying obvious facts. The questions are not about the gross facts, but about their interpretation, about what they mean and what they entail. Hence dualists cannot be refuted by citing any obvious facts. Indeed, if dualism could be refuted by citing empirical facts, it would not be a philosophical thesis at all.
I stress this, because many don't understand it. They think that substance dualists deny facts that are well-known or scientifically established. One commenter, for example, compared substance dualists to flat-earthers — which of course shows total misunderstanding.
"Why is this the case, if our minds aren't simply something the brain is doing?" Because it could be the case even if our minds are not simply something the brain is doing. If substance dualism is true, then the mind is a substance. But note the following definition:
D1. X is a substance =df X is metaphysically capable of independent existence.
(D1) lays down what is meant by 'substance' in discussions about substance dualism in the philosophy of mind. That and that alone is what is meant by the term.
Note also that 'substance' has a half-dozen or so meanings and that in this context, 'substance' does not mean stuff. Thus the dualist cannot be blown out of the water by some such cheapshot as saying that he is committed to something self-contradictory like immaterial matter. (Not that Malcolm would reach for such a cheapshot.)
So for the dualist, the mind can exist without being embodied. But my mind, with which I am rather well acquainted, is an embodied mind. It is embodied as a matter of contingent fact, though not as a matter of metaphysical necessity. So it is not surprising that what goes on in my mind affects and is affected by what goes on in my brain and central nervous system. It is not surprising that the states of an embodied mind will be affected by alcohol in the bloodstream. In general, it is not suprising that (some) changes in the brain will bring about changes in the mind.
Since the facts that Malcolm adduces can be explained both materialistically and dualistically,, his adducing of said facts does not support materialism over dualism. Since the facts are consistent with both schemes, they do not entail either scheme.
So what Malcolm says in #1 is not a good reason to reject dualism. Of course, what I said in rebuttal does not provide a good positive reason to accept dualism over materialism. What I have done is merely remove a threat to the rationality of dualist belief.
Posted by William F. Vallicella on Wednesday October 26, 2005 at 2:25pm.