In "The Conscious Mind", Chalmers bases his claim that materialism has failed to provide an explanation for consciousness on a distinction between 'logical' and 'natural' supervenience, where logical supervenience simply means that if A supervenes on B, then B logically and necessarily entails A. Because we can logically conceive of a (philosophical) zombie, then it seems that consciousness cannot *logically* supervene on the physical. There is simply nothing in the physical description that entails or even *suggests* the arising of subjective experiences in any system, biological or otherwise. This is a well-trodden path of argumentation that I'm sure we're all familiar with. However, since it does appear that, empirically, consciousness supervenes on physical processes, then this supervenience must be "natural" rather than logical. It must arise due to some natural law that demands it does. So far so good, though what we end up with in Chalmers' book - "property dualism" - hardly seems like the nourishing meal a phenomenologically inclined philosopher might have hoped for. Bruno's version of comp seems like more nourishing fare than the the watery gruel of property dualism, but Chalmers' formulation of logical supervenience got me thinking again about the grit in the ointment of comp that I've never quite been able to get comfortable with. This is only another way of formulating an objection that I've raised before, but perhaps it encapsulates the issue neatly. We can really only say we've "explained" something when explicated the relationships between the higher order explanandum and some ontologically prior basis, demonstrating how the latter necessarily entails the former. Alternatively we might postulate some new "brute fact", some hitherto unknown principle, law or entity which we accept because it does such a good job of uniting disparate, previously unexplained observations.
Now the UDA does a good job of making the case that if we accept the premise of comp (supervenience on computational states), then materialism can be seen to dissolve into "machine psychology" as Bruno puts it, or to emerge from arithmetic. But the problem here is that we can no more see mathematical functions as necessarily entailing subjective experience as we can see physical entities as doing so. It is perfectly possible to imagine computations occurring in the complete absence of consciousness, and in fact nearly everybody imagines precisely this. I would say that it is an undeniable fact that no mathematical function can be said to* logically entail *some correlated conscious state. Rather, we must postulate some kind of law or principle which claims that it is just so that mathematical functions, or certain classes thereof, co-occur with or are somehow synonymous with, conscious experiences. In other words, we are still forced back on a kind of natural supervenience. But the problem here is that, whereas with matter we may be able to invoke some kind of ontological 'magic' that "puts the fire into the equations" to quote Hawking, with pure mathematics it is hard to see how there can be any such natural law that is distinct from pure logic itself. Now when I've put this objection to Bruno in the past in slightly different words, claiming that it is hard to see any way to reconcile the language of mathematics with the language of qualia, Bruno has invoked Gödel to claim that mathematics is more than mere formalism, that it embodies a transcendent Truth that is beyond that which can be captured in any mathematical formulation. At least, that is the best summary I can make of my understanding of his reply. He also claims to have discovered the 'placeholder' for qualia within the mathematics of Löbian machines: the gap between statements which the machine knows to be true and those which the machine knows to be true and can prove to be so. It's a fascinating argument, but it seems at the very least incomplete. The fact that a machine making self-referentially correct statements will be able to assert some (true) things without being able to prove them does not compel me in any way to believe that such a machine will have a conscious experience of some particular phenomenal quality. It may be true that correct statements about qualia are correct statements which can't be proven, but this does not mean that statements about qualia are statements about unprovable mathematical propositions. I might claim that Chaitin's constant is 0.994754987543925216... and it might just happen that I'm right, through divine inspiration, but Chaitin's constant is not a quale of mine. Bruno can point to this space in his formalism to say "that's where the qualia fit", but there is a similar leap of faith involved to actually put them there as we make when attributing qualia to emergence from neurology. Gödel's theorem might show that mathematics is more than mere formalism, but it does not allow us to make the leap to mathematics being more than abstract relationships between numbers. There will always be some true, unprovable statement in any set of axioms, but this statement will still be about numbers, not about feelings. If we start to say mathematics is more than that, we are making a metaphysical, and indeed mystical claim, and I believe we have also expanded mathematics to become something else, something that we can no longer truly claim to be maths as that is usually understood. Now of course the "gap" between the maths and the qualia (I don't like the obfuscating and often confused language of Craig's posts, but I think "Gödel of the gaps" is a pretty good turn of phrase, if indeed he is pointing to the same thing as me) is actually imported into comp with the initial assumption of qualia supervening on computational states. That postulate is of course unexplained, mystifying and, when taken to its logical end as Bruno has done, mystical. But when all is said and done, we're still left with it as a "brute fact", if anything more naked than it was at the beginning of the argument. More naked because it is even less clear how we are going to get a natural law to bridge the gap between the putative ontological basis of consciousness and consciousness itself when that basis is pure mathematics. After all, what is mathematics? If it includes all consciousness, is inseparable from it, if it encompasses love, pain, the smell of rain, and everything else it is possible to experience, then we are really talking about the mind as a whole, and the claim of a reduction to arithmetic starts to look at the very least misleading. Arithmetic is just the sugar coating that gives the rationalist a better chance of swallowing the psychedelic pill. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
