Stephen Barr, with respect to Thomas Nagel’s much despised anti-materialism
book Mind and Cosmos, gets it exactly right:
The big question, of course, is whether minds can be understood completely in this way. Thomas Nagel contends that they cannot be and that materialism must therefore be false. His main argument is that materialism cannot account for three aspects of mind: consciousness, cognition (specifically, certain features of human rationality), and the human capacity to apprehend objective values. He argues, moreover, that even if materialism could explain how minds can exist in a purely physical world, it has no plausible account of how and why they did in fact come to exist. Darwinian evolution, being a purely physical theory, is not enough.
For mind (or consciousness) to be fully explained in purely physical terms, or,
more importantly, for a materialist account of consciousness to be true, mental states and brain states have to be one and the same. It’s not enough that both be correlated or causative, they have to be exactly the same.
To see how absurd this is, here’s an example: Pope Benedict is Cardinal Ratzinger. There’s not one Pope Benedict and one Cardinal Ratzinger, there’s just this guy who is both Pope Benedict and Cardinal Ratzinger. By the same token, a mental state (like the experience of the color red, say) and a brain state (like a bunch of neurons firing, say) must be, at least for the materialist, one and the same — and in the manner, I should add, that Benedict is Ratzinger.
But how can this be?
Certainly there’s no strain in seeing how they’re correlated, or even how one causes the other, but that they’re one and the same thing seems to be more than just intuitively false.
This is a point of which some (actually, a lot of) materialists I’ve encountered aren’t fully aware. They’ll often — and, often risibly — point to the fact that we can see, through neural-imaging technology, brain states evoking specific mental states, which is, to them, apparently evidence that both brain and mental states are one and the same.
But that one produces the other and therefore both are one and the same seems to me to be obviously false. If anything, much like how flipping a switch opens a light bulb, it simply means that a brain state can evoke a mental state, full stop. In much the same way that the flipping of the switch is not the illumination of the bulb (and not in the way that Cardinal Ratzinger is Pope Benedict), the brain state is not the mental state. Indeed, it simply does not follow they are one and the same, and that, owing to their obvious qualitative differences, they cannot even in principle be said to be one and the same, in which case purely materialistic accounts of the mind are untenable.
Of course, non-theists like Chalmers and Nagel, who can be said to have given up on materialism, and have thusly earned the ire of a lot of the militant materialists, have proposed other, let’s say, friendly-to-theism solutions to the mind-body rut. Chalmers, for instance, defends a form of dualism that’s much unlike the more parochial Cartesian ‘ghost in the machine’, while Nagel is a neutral monist, which to me seems to be a view that is eerily similar to panpsychism. To make the long story short, however, the fantasy of the science fetishists the world over (particularly of those ‘brights’ of the new atheist cabal) that science will in time give us a complete picture of reality, is slowly seeming to be unrealizable.