As Chalmers puts it, "Fodor comes surprisingly close to endorsing a form of property dualism with fundamental laws connecting physical processes and consciousness."

Now, philosophy of mind is not my research field. I teach some introductory philosophy of mind materials in a couple of the first-year-level subjects that I'm involved in from time to time, but I make no claim at all to being a philosopher of mind or to keeping up with the detail of the debates. I am, however, strongly inclined to an overall position of metaphysical or philosophical naturalism, in which all that exist are the phenomena (entities, properties, forces, space-time geometry, etc.) investigated by science. However, I've never understood why the sort of position that Fodor and Chalmers are describing is not compatible with philosophical naturalism.

The position for which Fodor expresses some sympathy is this:

I suppose one can imagine a world where all the big things are made out of small things, and there are laws about the small things and there are laws about the big things, but some laws of the second kind don’t derive from any laws of the first kind. In that world, it might be a basic law that when you put the right sorts of neurons together in the right sorts of way, you get a subject of consciousness. There would be no explaining why you get a subject of consciousness when you put those neurons together that way; you just do and there’s the end of it. Perhaps Strawson would say that in such a world, emergence would be a miracle; but if it would, why isn’t every basic law a miracle by definition?

Indeed, what we do seem to know is that consciousness actually exists: more precisely, I know that I am conscious, and I am prepared to assume that you are; the world simply makes much more sense if I do not adopt a position of solipsism, but work on the basis that at least those other beings who are much like me are conscious, though it is an open question how far down this extends. Are chimps conscious? Are cows? Alligators? Oysters? Paramecia? Still, the fact that I and the people I find myself associating with have conscious experience does indeed appear to be undeniable.

The next point is that it is difficult to explain how consciousness can emerge from matter merely by way of the kinds of physical laws that we know or are developing. It is hard to see how they can explain consciousness while making no reference to it. As Strawson and Fodor both discuss, it does not seem to be like liquidity, where, in principle, we seem to be able to explain the behaviour of liquid substances via an understanding of how molecules behave, which can be explained by how atoms behave and so on. Liquidity itself need never be mentioned: the basic laws will tell us how certain kinds of substances will coalesce and flow, etc. We can "eliminate" liquidity in a way that consciousness seems to be ineliminable.

All of this seems to entail that laws relating to the circumstances in which consciousness emerges from the functioning of some kinds of complex material substrates will have to refer to consciousness itself. Consciousness is not something that can be eliminated from the most basic equations. This, in turn, suggests that there are fundamental psychophysical laws that cannot be reduced to laws that do not mention consciousness.

But why is that so counterintuitive? It looks as if consciousness depends on matter, as if the nature of the dependence is lawful, and as if laws that never actually mention consciousness could not describe the dependence all by themselves. Does this not suggest that the laws governing the natural universe include irreducibly psychophysical ones?

Perhaps the worry is that these laws will be nothing like the fundamental laws of physics relating to, say, quantum events or the shape of space-time, but I'm not sure that that would trouble us if we were better placed to know more about what the psychophysical laws actually are. If we had some kind of handle on that, they might not seem any more intrinsically bizarre than anything else that science has discovered over the past 400-odd years.

The great difficulty that we face is that no one is in a position to observe consciousness directly (except his or her own). That makes it pretty much impossible to conduct experiments in which we predict that consciousness will be brought into being by such and such physical systems (in accordance with such and such conjectured psychophysical laws). Isn't that, however, just an epistemic limitation that we contingently labour under, no different in principle from the obvious fact that we are not well placed, epistemically, to determine such things as whether an alligator or an oyster is conscious? Yet, we accept the latter limitation on our knowledge and our ability to make progress. We may not like it, but we accept that it exists.

If all this reasoning goes through, the so-called Hard Problem of how to explain consciousness is, indeed, very difficult, but the difficulty is not that mind-boggling, entirely unknown, metaphysical concepts are needed. It is simply that, as an empirical fact, we are poorly situated to investigate (at least in any systematic manner) what regularities apply to the emergence of consciousness. Consciousness may be as much a part of the natural world as anything else, and as open, in principle, to causal explanation in terms of general laws. And yet, we might be in a situation where we are not well-placed to conduct the investigation and work out exactly what those laws are.

That would be unfortunate, of course, since it would mean that some scientific investigations would have to be recognised as very difficult for human beings to pursue to finality (indeed, it is hard to see how they could ever be pursued to finality, at least by us ... but who knows, in advance, the limits of our ingenuity?). It's unfortunate, yes. However, it doesn't seem especially counterintuitive or spooky. It is not letting in the supernatural, or anything as hard to conceive of at all as objective prescriptivity. It does not, for example, entail that full consciousness and all the associated cognitive capacities spring back into existence after a badly damaged brain is totally destroyed, that we are immortal, that there are substantial things ("minds") with no location in space, or more generally that consciousness is a substance that could survive independently of any material substrate (such as organised masses of neurons).

It would just be admitting that consciousness, though a part of the natural universe, cannot be eliminated from our most basic descriptions of how the universe operates, while also admitting something that seems plain anyway: the great contingent difficulty in working out for sure what physical systems are actually conscious and what systems are not. I could live with that. In fact, those admissions seem reasonably intuitive to my particular scientifically-aware sensibility.

This is a rare foray into philosophy of mind by someone who is relatively naive about the field, but I wonder what is actually wrong with the above analysis. Even if what I have sketched is a kind of dualism - a property dualism in that a new category of properties is being considered basic within the most fundamental laws governing the universe - I'm not sure that that is beyond the pale for philosophical naturalists. I am, of course, saying that there could be different degrees to which we are well- or ill-placed to investigate certain kinds of observed phenomena, but that does not seem very surprising, really, and it does not seem to constitute a betrayal of naturalism or of anything that I'd want to build on it.