Picture: Jaegwon Kim. David Chalmers recently commented that Jaegwon Kim’s new book ‘Physicalism, or something near enough’ showed how old-fashioned materialism was slipping in the popularity stakes: not suffering wholesale rejection exactly, but no longer enjoying the status of a near-unchallenged orthodoxy.

Kim himself says that the book offers no startlingly new views, only a clearer and better argued case. But the interest of some readers has at least been distinctly quickened by the main conclusion; that physicalism is nearly, but not quite, the whole truth. How can that be? At first sight, claiming that one is nearly a physicalist is about as plausible as claiming that one is nearly a virgin: in such cases even the most progressive logicians would generally exclude the middle. How can you have more than one fundamental substance without having two?

On reflection, however, I can see some attractions in that way of thinking. After all, physicists and mathematicians sometimes talk about spatial dimensions in fractional terms. If one can coherently have a space which is not 3- or 4-, but 4½- dimensional, why not fractional substances? What about a graduated ontological scale? We might say that anything over 1.5 counts as dualist, while anything less passes as monism; substance dualists would be up in the 1.8 to 1.9 range, while property dualists generally scored around 1.6 to 1.7. Only the most obdurate materialists would manage a 1.0, while some bold souls – Penrose, Popper? – would score values in excess of 2.0. Scores below 1.0 would surely be unattainable, unless perhaps reserved for the softer kinds of idealism (‘life is but a dream’).

In fact, joking aside, I really think that the scope for vagueness provided by such a scale might depict the discussion in realistic terms. It seems to me that if the fundamental argument over dualism is interpreted too strictly, there is a straight choice between monism and epiphenomenalism. If your second fundamental stuff is really detached from the first, it must be an irrelevant epiphenomenon which you might as well forget about; if, instead, it has at least some causal connections with the first, you might as well exercise ontological economy and regard both stuffs as part of a single comprehensive world (after all, believing in energy as well as matter doesn’t make you a dualist; so why should believing in suitably causal spirits?). A general application of the latter approach would, of course, have the strange effect of reclassifying nearly everyone, including Descartes, as monists – whether they knew it or not.

In practice a dualist is not generally someone who believes in the utter, unbridgeable bifurcation of the universe, but someone who believes that a twofold division of some kind is especially salient: more important than the distinction between energy and matter, but not so important that the world falls apart down the middle. The precise degree of salience might indeed be a matter for a graduated scale. Perhaps there’s actually less ontology involved than meets the eye: perhaps we should be better off, in most cases, if we saw the choice of monism or dualism as more a matter of expositional strategy than fundamental principle. One reason we don’t, I suspect, is that people have a strong desire to exclude ghosts and Christian spirits from their theories, and dualism (which need not actually involve souls or spirits at all) gets used as a proxy. Perhaps that’s also why Descartes keeps on getting such a bad press: not really for dualism per se, but for a dualism which explicitly made room for Jehovah.

So then, maybe in principle it’s alright to be nearly a physicalist – so long as the theory itself is OK. What is the nature of Kim’s dualism, or small lapse from perfect physicalism?

The bulk of the discussion is taken up with establishing Kim’s basic physicalism, with the ‘lapse’ discussed mainly at the end of the book. If we want mental events to have real causal power (and we surely do), Kim argues that they must be reducible in principle to the physical level. He carefully distinguishes this view from eliminative reductionism: phlogiston, he says, was eliminated, and thereby banished from science, while heat and temperature were reduced, and remain useful concepts. Moreover, after a careful survey of the options it turns out that the only kind of reduction available is a functional one.

This is all fairly persuasive, though not so seductive that it is likely to make many converts, and it leads us to a pretty familiar position: it turns out that many mental events are susceptible to functionalist reduction, and can therefore be brought within the pale of physicalism. We may not be able to spell out the account in full, but we have a pretty good idea of its broad outline. The problem, as ever, is qualia. Qualia are not susceptible to functional reduction (the possibility of inverted qualia is sufficient to establish this: Kim rather loftily remarks that we don’t need any of that zombie stuff). The distinctive feature of Kim’s analysis is that he nevertheless wants to take another slice off the unsolved problem; claim the border regions of the qualia country for physicalism. This he does by asserting that while qualia in themselves cannot be characterised in functional terms, differences between qualia can. So, it would not matter in practical terms if the real experience of red and green were switched: we should still be able to interpret traffic lights correctly. But if there were no difference between the real experiences, we should be in trouble. Thus qualia do have a real causal role, though in their essence they remain ineffable.

It’s this move which allows Kim to claim he’s still really a physicalist; even qualia have been naturalised and given a role; the fact that they still have an inscrutable phenomenal aspect isn’t a cause for concern. The tone of Kim’s conclusion makes it clear that he regards this as an acceptable final position; he isn’t in despair over qualia and he isn’t looking for more to say about them, either.

This seems a little strange, even on Kim’s own terms. An inexplicable feature of the world just demands philosophical attention: you expect a philosopher to respond to a hint of the unexplained in the way a mother responds to a faint sound of crying. In Kim’s eyes, the problem has been substantially reduced; but half a problem is still a problem. I do have some sympathy with idea that people worry too much about qualia, but that’s because I think there’s an element of confusion about the whole thing: a kind of clerkish surprise that accounts or explanations of experience don’t bring with them the experience itself. On Kim’s account, a significant portion of the old problem is still there: he just somehow manages not to worry about it.

I’m not convinced that the argument about differences really works, anyway. In the first place, is it really true that qualia play a causal role in our response to traffic lights? It’s certainly possible to detect the difference between red and green, and respond accordingly, without any trace of qualia: quite simple machines could do so, and it rather looks as if the brain uses some broadly similar mechanisms. I suppose we could argue that qualia over-determine or somehow help out with the response, but it seems easier to conclude that these functionalizable qualities which Kim is talking about are not really qualia at all.

Secondly, doesn’t our ability to spot differences between qualia depend causally on our ability to perceive them in the first place? It seems to me that we see the difference between red and green qualia only because we actually see green and red. But if that is so, and if our perception of qualia differences has a causal role in determining our behaviour, then qualia themselves also have a causal role, albeit one step removed.

I suspect there is something in what David Chalmers says about a noticeable swing away from monist materialism; but I also suspect that the reasons are more to do with despair over the current impasse than any new and stronger case for dualism. You could see Kim’s theory as another desperate effort to find a novel yet plausible way forward – an effort which nearly succeeds. Unfortunately, in this case, nearly really is the same as not at all.

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