One common argument against substance (mind-body) dualism runs as follows. We know that consciousness is dependent on the brain, because when the brain is damaged it adversely affects consciousness and mental function. (You can prove this point to yourself experimentally by hitting yourself hard on the head with a brick.) Furthermore, it is argued, when brain function ceases altogether, consciousness disappears. (Don’t try to prove this latter point to yourself experimentally; just take it on trust.) Therefore, contra substance dualism, the mind — if it’s a real entity at all — must be ontologically dependent on the physical structures of the brain. We should be physicalists of some kind.
I come across this argument all the time in the writings of naturalists, but it strikes me as a blatant non sequitur. At most it shows that there’s a causal relationship between the mind and the body, which substance dualists insist upon anyway. (The so-called “interaction problem,” which is concerned with how there can be causation between physical and non-physical substances, is a different challenge to dualism, one I don’t propose to address here.) The fact that increasing damage to the brain leads to increasing mental impairment doesn’t at all imply that the mind cannot exist apart from the brain.
Here’s an analogy to elucidate why that’s so. Imagine a spaceship of the kind familiar from sci-fi movies. In this spaceship, the cockpit doubles up as an escape pod. In normal operation, the cockpit is attached to the main ship; whenever the ship moves, the cockpit moves with it, just as it should. If the ship is attacked with (say) photon torpedoes, the cockpit is buffeted about along with the rest of the spacecraft. When the ship is damaged, all of its systems can be affected; thus the operation of the cockpit can be impaired by damage to the ship in which it is housed.
If the ship becomes so badly damaged that it can’t move at all, the cockpit is stuck along with it, since it’s fixed to the ship. But if the spaceship is completely blown apart, the cockpit functions as an escape pod: it can detach from the doomed ship, and once detached, it can move freely again. (In line with a Christian eschatology, we could even extend the analogy such that if the parts of the ship are recovered and reassembled, the cockpit can be reattached — but that’s not necessary for the point I’m making here.)
Alvin Plantinga on Russell’s teapot, from a 2014 interview by Gary Gutting:
G.G.: You say atheism requires evidence to support it. Many atheists deny this, saying that all they need to do is point out the lack of any good evidence for theism. You compare atheism to the denial that there are an even number of stars, which obviously would need evidence. But atheists say (using an example from Bertrand Russell) that you should rather compare atheism to the denial that there’s a teapot in orbit around the sun. Why prefer your comparison to Russell’s?
A.P.: Russell’s idea, I take it, is we don’t really have any evidence against teapotism, but we don’t need any; the absence of evidence is evidence of absence, and is enough to support a-teapotism. We don’t need any positive evidence against it to be justified in a-teapotism; and perhaps the same is true of theism.
I disagree: Clearly we have a great deal of evidence against teapotism. For example, as far as we know, the only way a teapot could have gotten into orbit around the sun would be if some country with sufficiently developed space-shot capabilities had shot this pot into orbit. No country with such capabilities is sufficiently frivolous to waste its resources by trying to send a teapot into orbit. Furthermore, if some country had done so, it would have been all over the news; we would certainly have heard about it. But we haven’t. And so on. There is plenty of evidence against teapotism. So if, à la Russell, theism is like teapotism, the atheist, to be justified, would (like the a-teapotist) have to have powerful evidence against theism.
Plantinga goes on to discuss whether there is such evidence, whether there are any good arguments for or against atheism, and whether theistic beliefs need to be justified by philosophical arguments. He concludes with a nice summary of his Evolutionary Argument Against Naturalism.
My review of Thomas Nagel’s Mind and Cosmos has been posted on the Reformation 21 website.
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My review of Keith Ward’s book Why There Almost Certainly Is a God has been posted over at Discerning Reader.
The words “Not recommended” in bold red font at the top of the review make it look as though I’m more down on Ward’s book than I am, but the review itself should make clear why, despite the cogency of its central argument, I couldn’t recommend the book for DR’s particular constituency.