Quentin Ruyant has written a thoughtful piece about quantum mechanics and philosophy of mind: in a nutshell he argues both that quantum theory may be relevant to the explanation of consciousness and that consciousness may be relevant to the interpretation of quantum theory.

Is quantum theory relevant to consciousness? Well. of course some people have said so, notably Sir Roger Penrose and Stuart Hameroff.  I think Ruyant is right, though, that the majority of philosophers and probably the majority of physicists dismiss the idea that quantum theory might be needed to explain consciousness. People often suggest that the combination of the two only appeals because both are hard to explain: ‘here’s one mystery and here’s another: maybe one explains the other’. Besides, people say, the brain is far too big and hot and messy for anything other than classical physics to be required

In making the case for the relevance of quantum theory, Ruyant relies on the Hard Problem.  His position is that the Hard Problem is not biological but a matter of physics, whereas the Easy Problem, to do with all the scientifically tractable aspects of consciousness, can be dealt with by biology or psychology.

Actually, turning aside from the main thread of Ruyant’s argument, there are some reasons to suggest that quantum physics is relevant to the Easy Problem. Penrose’s case, in fact, seems to suggest just that: in his view consciousness is demonstrably non-computable and some kind of novel quantum mechanics is his favoured candidate to fill the gap. Penrose’s examples, things like solving mathematical problems, look like ‘Easy’ Problem matters to me.

Although I don’t think anyone (including me) advocates the idea, it also seems possible to argue that the ‘spooky action at a distance’ associated with quantum entanglement might conceivably have something to tell us about intentionality and its remarkable power to address things that are remote and not directly connected with us.

Anyway, Ruyant is mainly concerned with the Hard Problem, and his argument is that metaphysics and physics are closely related. Topics like the essential nature of physical things straddle the borderline between the two subjects, and it is not at all implausible therefore that the deep physics of quantum mechanics might shed light on the deep metaphysics of phenomenal experience. It seems to me a weakish line of argument, possibly tinged with a bit of prejudice: some physicists are inclined to feel that while their subject deals with the great fundamentals, biology deals only with the chance details of life; sort of a more intellectual kind of butterfly collecting.  That kind of thinking is not really well founded, and it seems particularly odd to think that biology is irrelevant when considering a phenomenon that, so far as we know, appears only in animals and is definitely linked very strongly with the operation of the brain. John Searle for one argues that ‘Hard Problem’ consciousness arises from natural biological properties of brain tissue. We don’t yet know what those properties are, but in his view it’s absurd to think that the job of nerves could equally well be performed by beer cans and string. Ruth Millikan, somewhat differently, has argued that consciousness is purely biological in nature, arising from and defined by evolutionary needs.

I think the truth is that it’s difficult to get anywhere at this meta-theoretical level:  we don’t really decide what kind of theory is most likely to be right and then concentrate on that area; we decide what the true theory most likely is and then root for the kind of theory it happens to be. That, to a great extent, is why quantum theories are not very popular: no-one has come up with a particular one that is cogent and appealing.  It seems to me that Ruyant likes the idea of physics-based theories because he favours panpsychism, or panphenomenalism, and so is inclined to think that the essential nature of matter is likely to be the right place to look for a theory.

To be honest, though, I doubt whether any kind of science can touch the Hard Problem.  It’s about entities that have no causal properties and are ineffable: how could empirical science ever deal with that? It might well be that a scientist will eventually give us the answer, but if so it won’t be by doing science, because neither classical nor quantum physics can really touch the inexpressible.

Actually, though there is a long shot.  If Colin McGinn is partly on the right track, it may be that consciousness seems mysterious to us simply because we’re not looking at it the right way: our minds won’t conceptualise it correctly. Now the same could be true of quantum theory. We struggle with the interpretation of quantum mechanics, but what if we could reorient our brains so that it simply seemed natural, and we groped instead for an acceptable ‘interpretation’ of spooky classical physics? If we could make such a transformation in our mental orientation, then perhaps consciousness would make sense too? It’s possible, but we’re back to banging two mysteries together in the hope that some spark will be generated.

Ruyant’s general case, that metaphysicians should be informed by our best physics is hard to argue with. At the moment few philosophers really engage with the physics and few physicists really grasp the philosophy. Why do philosophers avoid quantum physics? Partly, no doubt, just because it’s difficult, and relies on mathematics which few philosophers can handle. Partly also, I think there’s an unspoken fear that in learning about quantum physics your intuitions will be trained into accepting a particular weltanschauung that might not be helpful. Connected with that is the fear that quantum physics isn’t really finished or definitive. Where would I be if I came up with a metaphysical system that perfectly supported quantum theory and then a few years later it turns out that I should have been thinking in terms of string theory? Metaphysicians cross their fingers and hope they can deal with the key issues at a level of generality that means they won’t be rudely contradicted by an unexpected advance in physics a few years later.

I suppose what we really need is someone who can come up with a really good specific theory that shows the value of metaphysics informed by physics, but few people are qualified to produce one. I must say that Ruyant seems to be an exception, with an excellent grasp of the theories on both sides of the divide. Perhaps he has a theory of consciousness in his back pocket…?