Consciousness is all the rage just now. It boasts new journals of its very own, from which learned articles overflow. Neuropsychologists snap its picture (in colour) with fMRI machines, and probe with needles for its seat in the brain. At all seasons, and on many continents, interdisciplinary conferences about consciousness draw together bizarre motleys that include philosophers, psychologists, phenomenologists, brain scientists, MDs, computer scientists, the Dalai Lama, novelists, neurologists, graphic artists, priests, gurus and (always) people who used to do physics. Institutes of consciousness studies are bountifully subsidised. Meticulous distinctions are drawn between the merely conscious and the consciously available; and between each of these and the preconscious, the unconscious, the subconscious, the informationally encapsulated and the introspectable. There is no end of consciousness gossip on Tuesdays in the science section of the New York Times. Periodically, Nobel laureates pronounce on the connections between consciousness and evolution, quantum mechanics, information theory, complexity theory, chaos theory and the activity of neural nets. Everybody gives lectures about consciousness to everybody else. But for all that, nothing has been ascertained with respect to the problem that everybody worries about most: what philosophers have come to call ‘the hard problem’. The hard problem is this: it is widely supposed that the world is made entirely of mere matter, but how could mere matter be conscious? How, in particular, could a couple of pounds of grey tissue have experiences?

Until quite recently, there were two main schools of thought on this. According to one, the hard problem is actually very easy: the answer is that consciousness ‘emerges’ from neural processes. This succeeds in replacing ‘what is consciousness and how is it possible?’ with ‘what is emergence and how is it possible?’ But it doesn’t seem to get much further; many find it less than satisfactory. According to the other view, the hard problem is so hard that it can’t be real: consciousness must be some sort of illusion. Many of this persuasion tried hard to convince themselves that they are, in fact, not conscious, but few of them succeeded. Centuries ago, Descartes suggested, plausibly, that the attempt is self-defeating.

There is, I should add, another way to respond to the hard problem. One might hold that the world isn’t made entirely of matter after all; there is also a fundamentally different kind of stuff – mind-stuff, call it – and consciousness resides in that. Notoriously, however, this view has hard problems of its own. For example, if matter-stuff and mind-stuff are of fundamentally different kinds, how are causal relations between them possible? How is it possible that eating should be caused by feeling peckish or feeling peckish by not eating? For this and other reasons, mind-stuff has mostly fallen out of fashion. I won’t dwell on it here.

That, then, sets the stage for Galen Strawson’s Consciousness and Its Place in Nature, which consists of a lead essay by Strawson, commentaries by 18 other philosophers, and Strawson’s extensive comments on the comments. The book is very rich. On the one hand, Strawson has the kind of expansive metaphysical imagination that used to be at the heart of philosophy, but which positivism and analysis succeeded for a long while in suppressing. Also, the commentaries are, almost uniformly, insightful, informative, sophisticated and excellently argued. It is very rare for a book with this sort of format to be so complete a success, or so much fun to read. I must warn you, however, that Strawson’s way with the hard problem is wildly at odds with the views current in most of philosophy and psychology. Many readers will find them too wild to swallow; I’m not at all sure that I don’t.

There are three philosophical principles to which Strawson’s allegiance is unshakeable. The first is that the existence of consciousness (specifically, of conscious experience) is undeniable; that we are conscious is precisely what we know best. (To be sure, we can’t prove that we are conscious; but that is hardly surprising since there is no more secure premise from which such a proof could proceed.) Strawson’s second principle is a kind of monism: everything that there is is the same sort of stuff as such familiar things as tables, chairs and the bodies of animals. This, however, leaves a lot of options open since Strawson thinks that nothing much is known about that kind of stuff ‘as it is in itself’; at best science tells us only about its relational properties. What is foreclosed by Strawson’s monism is primarily the sort of ‘substance dualism’ that is frequently (but, he thinks, wrongly) attributed to Descartes.

The third of Strawson’s leading theses is a good deal more tendentious than the first two; namely, that emergence isn’t possible. ‘For any feature Y of anything that is correctly considered to be emergent from X, there must be something about X and X alone in virtue of which Y emerges, and which is sufficient for Y.’ But Strawson holds that there isn’t anything about matter in virtue of which conscious experience could arise from it; or that if there is, we have literally no idea what it could be. In particular, we can’t imagine any way of arranging small bits of unconscious stuff that would result in the consciousness of the larger bits of stuff of which they are the constituents. It’s not like liquids (Strawson’s favourite example of bona fide emergence) where we can see, more or less, how constituent molecules that aren’t liquid might be assembled to make larger things that are. How on earth, Strawson wonders, could anything of that sort explain the emergence of consciousness from matter? If it does, that’s a miracle; and Strawson doesn’t hold with those.

It’s his refusal to budge an inch on any of this that makes his discussion so interesting. Whatever you think of his metaphysical conclusions, all three of his assumptions are pretty plausible, so it’s well worth asking what’s entailed if one agrees to them. Strawson is prepared to follow the trail to the very end. I, for one, think that’s how philosophy ought to be done. You can’t make metaphysics out of fudge.

So, then, if everything is made of the same sort of stuff as tables and chairs (as per monism), and if at least some of the things made of that sort of stuff are conscious (there is no doubt that we are), and if there is no way of assembling stuff that isn’t conscious that produces stuff that is (there’s no emergence), it follows that the stuff that tables, chairs and the bodies of animals (and, indeed, everything else) is made of must itself be conscious. Strawson, having wrestled his angel to a draw, stands revealed as a panpsychist: basic things (protons, for example) are loci of conscious experience. You don’t find that plausible? Well, I warned you.

Nor, having swallowed this really enormous camel, does Strawson propose to strain at the gnats. Consider, for example: he thinks (quite rightly) that there are no experiences without subjects of experience; if there’s a pain, it must be somebody or something’s pain; somebody or something must be in it. What, then, could it be that has the experiences that panpsychists attribute to ultimate things? Nothing purely material, surely, since that would just raise the hard problem all over again. So maybe something immaterial? But monism is in force; since the constituents of tables and chairs are made of matter, so too is everything else. So, Strawson is strongly inclined to conclude, the subjects of the experiences that basic things have must be the experiences themselves. Part of the surcharge that we pay for panpsychism (not, after all, itself an immediately plausible ontology) is that we must give up on the commonsense distinction between the experience and the experiencer. At the basic level, headaches have themselves.

Similar lines of thought lead to a forced choice between Strawson’s panpsychism and the traditional distinction between things and their properties. Contrary to naive intuit-ion, ‘Fodor’s headache’ doesn’t express a relation between something more or less permanent (Fodor) and something more or less transient (his headache). If that’s so, however, it threatens to make nonsense of counterfactual hypotheticals; ones which say what would be the case if a given thing had properties different from the ones it actually does (‘Fodor would have been happy if his headache had gone away’). And finally, having somehow got all those camels down, it’s not clear that Strawson has in fact arrived at an answer to the hard problem. Suppose that the little bits of me have (or are) conscious experiences. How does that account for my being conscious? If you have one experience and I have another, the total of our experiences comes to two; there isn’t a third experience of which the first two are the constituents. Well, if that’s true of you and me, why isn’t it also true of me and the little things I’m made of? How does their having their headaches help to explain my having mine?

I should emphasise that none of these objections has escaped Strawson’s attention. To the contrary, I’ve borrowed most of them from him. Having been up front about his problems, Strawson considers various strategies in response to them. Perhaps, for example, commonsense metaphysics really does have to be abandoned; perhaps, in particular, the object/property distinction will have to go. Strawson reads some such moral as already implicit in what’s been going on in recent physics; maybe he’s right to do so. And maybe there are mysteries we must learn to live with; goings-on that we just aren’t built to understand (or that our logic isn’t). Maybe the composition of big experiences out of little ones is among those.

In a way, I’m quite sympathetic to all that. I think it’s strictly true that we can’t, as things stand now, so much as imagine the solution of the hard problem. The revisions of our concepts and theories that imagining a solution will eventually require are likely to be very deep and very unsettling. (That’s assuming what’s by no means obvious: that we are smart enough to solve it at all.) Philosophers used to think (some still do) that a bit of analytical tidying up would make the hard problem go away. But they were wrong to think that. There is hardly anything that we may not have to cut loose from before the hard problem is through with us.

Still, all else being equal, whoever gives up least is the winner; so it matters whether Strawson has abandoned more than he needs to. I’m not convinced that we will have to throw overboard as much as he thinks we will. In particular, we might try denying the claim, cited above, that if Y emerges from X, then there must be something about X in virtue of which Y emerges from it. Why not just say: some things are true about the world because that’s the kind of world it is; there’s nothing more to make of it. That sounds defeatist perhaps; but it really isn’t since, quite plausibly, it’s the sort of thing that we will have to say sooner or later whether or not saying it would help with the hard problem.

Typical scientific explanations appeal to natural laws. Some natural laws are explained by appealing to others, but some aren’t; some of them are basic. So, roughly, the laws about molecules explain the laws about liquidity; and the laws about atoms explain the laws about molecules; and the laws about subatomic bits and pieces explain the laws about atoms . . . and so on down, but not so on down for ever. Eventually, we get to laws about whatever the smallest things are (or, perhaps, to laws about the fundamental structure of space-time); and there we simply stop. Basic laws can’t be explained; that’s what makes them basic. There isn’t a reason why they hold, they just do. Even if basic physical laws are true of everything, they don’t explain everything; in particular, they don’t explain why, of all the basic laws that there might have been, these are the ones there actually are. I don’t say that’s the right way to look at things, but it’s a perfectly respectable and traditional way. At a minimum, it seems that the various sciences form some sort of hierarchy, with physics (or whatever) at the bottom. That’s much as one might expect if the sort of view I’m discussing is at least approximately true.

Maybe, however, there’s something wrong with this view and we’ll finally have to do without it. Maybe the hard problem shows that not all basic laws are laws of physics. Maybe it shows that some of them are laws of emergence. If that’s so, then it’s not true after all that if Y emerges from X there must be something about X in virtue of which Y emerges from it. Rather, in some cases, there wouldn’t be any way of accounting for what emerges from what. Consciousness might emerge from matter because matter is the sort of stuff from which consciousness emerges. Full stop.

It would then have turned out that the hard problem is literally intractable, and that would be pretty shocking. The idea that the basic laws are the laws about the smallest things has been central to the ‘scientific world-view’ ever since there started to be one. On the other hand, as far as I can see, it’s not any sort of a priori truth. 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? I have my pride. I would prefer that the hard problem should turn out to be unsolvable if the alternative is that we’re all too dumb to solve it. All I ask is that the kind of unsolvable that it turns out to be has respectable precedents.

Anyhow, Strawson is right that the hard problem really is very hard; and I share his intuition that it isn’t going to get solved for free. Views that we cherish will be damaged in the process; the serious question is which ones and how badly. If you want an idea of just how hard the hard problem is, and just how strange things can look when you face its hardness without flinching, this is the right book to read.