The problem can be set forth in a nice neat way as an aporetic triad:
1) Consciousness is real; it is not an illusion.
2) Consciousness is wholly natural, a material process in the brain.
3) It is impossible that conscious states, whether object-directed or merely qualitative, be material in nature.
It is easy to see that the members of this triad are collectively inconsistent: they cannot all be true. Any two of the propositions, taken together, entails the negation of the remaining proposition.
And yet each limb of the triad has brilliant defenders and brilliant opponents. So not only is consciousness itself a mighty goad to inquiry; the wild diversity of opinions about it is as well. (The second goad is an instance of what I call the Moorean motive for doing philosophy: G. E. Moore did not get his problems from the world, but from the strange and mutually contradictory things philosophers said about the world, e.g., that time is unreal (McTaggart) or that nothing is really related (Bradley).)
The above problem is soluble if a compelling case can be made for the rejection of one of the limbs. But which one? Eliminativists reject (1); dualists of all types, and not just substance dualists, reject (2); materialists reject (3).
I agree with Strawson that eliminativism has zero credibility. (1) is self-evident and the attempts to deny it are easily convicted of incoherence. So no solution is to be had by rejecting (1).
As for (2), it is overwhelmingly credible to most at the present time. We live in a secular age. 'Surely' -- the secularist will assure us -- there is nothing concrete that is supernatural. God and the soul are just comforting fictions from a bygone era. The natural exhausts the real. Materialism about the mind is just logical fallout from naturalism. If all that (concretely) exists is space-time and its contents, then the same goes for minds and their states.
Strawson, accepting both (1) and (2) must reject (3). But the arguments against (3), one of which I will sketch below, are formidable. The upshot of these arguments is that it is unintelligible how either qualia or intentional states of consciousness could be wholly material in nature. Suppose I told you that there is a man who is both fully human and fully divine. You would say that that makes no sense, is unintelligible, and is impossible for that very reason. Well, it is no less unintelligible that a felt sensation such as my present blogger's euphoria be identical to a state of my brain.
What could a materialist such as Strawson say in response? He has to make a mysterian move.
He could say that our understanding of matter at present does not allow us to understand how conscious experience could be wholly material in nature, but that it is nevertheless wholly material in nature! Some matter is sentient and some matter thinks. My euphoria is literally inside my skull and so are my thoughts about Boston.
(Compare the orthodox Chalcedonian incarnationalist who says that the man Jesus of Nazareth is identical to the Second Person of the Trinity. Put him under dialectical pressure and he might say, "Look it is true! We know it by divine revelation. And what is true is true whether or not we can understand how it is possible that it be true. It must remain a mystery to us here below.)
Or a materialist mysterian can say that our understanding of matter will never allow us to understand how conscious experience could be wholly material in nature. Either way, conscious experience, whether intentional or non-intentional, is wholly material in nature, and falls entirely within the subject-matter of physics, whether a future physics achievable by us, or a physics which, though not achievable by us, is perhaps achievable by organisms of a different constitution who study us.
If I understand Galen Strawson's view, it is the first. Conscious experience is fully real but wholly material in nature despite the fact that on current physics we cannot account for its reality: we cannot understand how it is possible for qualia and thoughts to be wholly material. Here is a characteristic passage from Strawson:
Serious materialists have to be outright realists about the experiential. So they are obliged to hold that experiential phenomena just are physical phenomena, although current physics cannot account for them. As an acting materialist, I accept this, and assume that experiential phenomena are "based in" or "realized in" the brain (to stick to the human case). But this assumption does not solve any problems for materialists. Instead it obliges them to admit ignorance of the nature of the physical, to admit that they don't have a fully adequate idea of what the physical is, and hence of what the brain is. ("The Experiential and the Non-Experiential" in Warner and Szubka, p. 77)
Strawson and I agree on two important points. One is that what he calls experiential phenomena are as real as anything and cannot be eliminated or reduced to anything non-experiential. Dennett denied! The other is that there is no accounting for experiential items in terms of current physics.
I disagree on whether his mysterian solution is a genuine solution to the problem. What he is saying is that, given the obvious reality of conscious states, and given the truth of naturalism, experiential phenomena mustbe material in nature, and that this is so whether or not we are able to understand how it could be so. At present we cannot understand how it could be so. It is at present a mystery. But the mystery will dissipate when we have a better understanding of matter.
This strikes me as bluster.
An experiential item such as a twinge of pain or a rush of elation is essentially subjective; it is something whose appearing just is its reality. For qualia, esse = percipi. If I am told that someday items like this will be exhaustively understood from a third-person point of view as objects of physics, I have no idea what this means. This is an empty gesturing toward an inconceivable 'possibility.' We are being told in effect that what is essentially subjective will one day be exhaustively understood as both essentially subjective and wholly objective. And that makes no sense. If you tell me that understanding in physics need not be objectifying understanding, I don't know what that means either.
As Strawson clearly appreciates, one cannot reduce a twinge of pain to a pattern of neuron firings, for such a reduction eliminates the what-it-is-like-ness of the experience. And so he inflates the concept of the physical to cover both the physical and the mental. But by doing this he drains the physical of definite meaning. His materialism is a vacuous materialism. We no longer have any idea of what 'physical' means if it no longer contrasts with 'mental.'
If we are told that sensations and thoughts are wholly material, we have a definite proposition only if 'material' contrasts with 'mental.' But if we are told that sensations and thoughts are material, but that matter in reality has mental properties and powers, then I say we are being told nonsense. We are being handed grammatically correct sentences that do not express a coherent thought.
Besides, if some matter in reality senses and thinks, surely some matter doesn't; hence we are back to dualism.
Why is Strawson's mysterianism any better than Dennett's eliminativism? Both are materialists. And both are keenly aware of the problem that qualia pose. This is known in the trade as the 'hard problem.' (What? The other problems in the vicinity are easy?) The eliminativist simply denies the troublesome data. Qualia don't exist! They are illusory! The mysterian materialist cannot bring himself to say something so manifestly silly. But, unwilling to question his materialism, he says something that is not much better. He tells us that qualia are real, and wholly material, but we don't understand how because we don't know enough about matter. But this 'theological' solution is also worthless because no definite proposition is being advanced.
Strawson frankly confesses, "I am by faith a materialist." (p. 69) Given this faith, experiential items, precisely as experiential, must be wholly material in nature. This faith engenders the hope that future science will unlock the secret. Strawson must pin his hope on future science because of his clear recognition that experiential items are incomprehensible in terms of current physics.
But what do the theological virtues of faith and hope have to do with sober inquiry? It doesn't strike me as particularly intellectually honest to insist that materialism just has to be true and to uphold it by widening the concept of the physical to embrace what is mental. It would be more honest just to admit that the problem of consciousness is insoluble.
And that is my 'solution.' The problem is real, but insoluble by us.
Strawson's latest banging on his mysterian materialist drum is to be found in The Consciousness Deniers in The New York Review of Books.