The central defining property of the mind is consciousness, so philosophy of mind is concerned with the existence and nature of consciousness: what is consciousness, why does it exist, how is it related to the body and brain, and how did it come into existence?After discussing a few more problems with eliminativism McGinn offers his assessment of dualism, and here I think he's a bit off the mark:
These are big, difficult questions. Focus on your current state of consciousness - your experience of seeing, hearing, feeling, thinking, willing, and so on - and ask yourself what kind of being this consciousness is, what its function might be, how it is related to the activity of cells in your brain, what could have brought it about in the course of evolution. Allow yourself to feel the attendant puzzlement, the sense of bafflement: now you are doing philosophy of mind.
We can distinguish five positions on consciousness: eliminativist, dualist, idealist, panpsychist and mysterianist. The eliminativist position attempts to dissolve the problem of explaining consciousness simply by declaring that there isn't any: there is no such thing - no seeing, hearing, thinking, and so on. There is just blank matter; the impression that we are conscious is an illusion.
This view is clearly absurd, a form of madness even, and anyway refutes itself since even an illusion is the presence of an experience (it certainly seems to me that I am conscious). There are some who purport to hold this view but they are a tiny (and tinny) minority: they are sentient beings loudly claiming to be mindless zombies.
The dualist, by contrast, freely admits that consciousness exists, as well as matter, holding that reality falls into two giant spheres. There is the physical brain, on the one hand, and the conscious mind, on the other: the twain may meet at some point but they remain distinct entities. Dualism may be of substances, properties, or even whole universes, but its thrust is that the conscious mind is a thing apart from, and irreducible to, anything that goes on in the body.Well, no, not really. Dualists look at the relation of the mind to the brain something like the relationship of the wi-fi signal to a computer. The image on the computer's screen (a downloaded movie, for example) depends upon both the computer and the signal. Neither by itself is able to generate the image on the screen, and just as any alteration in either produces an alteration in the image so, too, any alteration in either the mind or the brain produces an alteration in our mental experience. Dualism sees the two, mind and brain, as tightly integrated though ontologically distinct.
Dualism proposes to give the mind its ontological due but the problem is that it has difficulties organising a rendezvous between the two spheres: how does the mind affect the brain and the brain the mind? Whence the systematic correlation and interaction? And how did the mind come to exist, if not by dint of cerebral upsurges? Dualism makes the mind too separate, thereby precluding intelligible interaction and dependence.
Moreover, the objection that it's difficult to see exactly how the mind and brain could interact is no impediment to believing that they do any more than the difficulty in seeing how gravitational force acts on an object to pull it down is also an impediment to believing that it does. Indeed, science cannot explain how any of the fundamental forces of nature - gravity, electromagnetism, the strong nuclear or the weak nuclear - actually cause the effects they do, but that's not considered an impediment to accepting that they nevertheless do cause those effects.
I also think McGinn's critique of idealism falls a little short. He writes that:
At this point the idealist swooshes in: ladies and gentlemen, there is nothing but mind! There is no problem of interaction with matter because matter is mere illusion - we merely hallucinate brains. The universe is just one vast spirit, or perhaps a population of the same, consisting of nothing but free-floating consciousness, unencumbered and serene. Stars and planets are just perturbations in this cosmic sensorium.If being an idealist requires a "maniacal antipathy toward matter" then at least some modern physicists are maniacs. Physics is showing that matter is, at bottom, a kind of illusion. If you go to this site and scroll all the way to the very smallest sizes it turns out that all there is, all that matter consists in, is unbelievably tiny vibrating wisps of energy. Solid matter is simply an illusion that results from us perceiving the world on the scale of size we do.
As an imaginative fancy, idealism has its charms but taking it seriously requires an antipathy to matter bordering on the maniacal. Are we to suppose that material reality is just a dream, a baseless fantasy, and that the Big Bang was nothing but the cosmic spirit having a mental sneezing fit? Where did consciousness come from, if not from pre-existing matter? Did God just create centres of consciousness ab initio, with nothing material in the vicinity? Is my body just a figment of my imagination?
If that's so then "matter" really is somehow a construct of our minds, or at least a construct of some mind. One of the most famous idealists, the Irish philosopher George Berkeley (d.1753), thought the material world was pretty much an idea in the mind of God.
McGinn finishes with a discussion of both panpsychism and the view he prefers, what he calls mysterianism. It's all pretty interesting and you might want to take a couple of minutes to read it.