Philosophy Bat-man

Thomas Nagel's essay "What is it like to be a bat ?" is famous for pointing out the subjective nature of experience. I need not dwell on the Hard Problem and all that; chances are if you're reading this you're probably more familiar than I am with the whole shebang.

Still, I've never read Nagel's original article, making it extremely presumptuous of me to write a piece, "What would it be like to be a ghost ?". Ah, but that, dear reader, is the great virtue of blogs : absolutely sod-all I write here matters. I claim no authority so you should expect none.

But yesterday I did finally read the original piece. I liked it. Given the multitude of internet pieces about this that I've read, there wasn't too much that came as a surprise - it's a bit like watching an original movie after seeing its derivatives (though much of it - indeed the very heart of it - can be found a couple of centuries earlier in John Locke). It's still a nice read, well worth the short amount of your time it will take if you're interested in this sort of thing. It's an excellent summary which does a good job of getting to the core of the problem.

I'm not doing to do a detailed analysis of this one, firstly because I've covered all this before, and secondly because it's so well-known as to make my contribution even more pointless than usual. What I do want to point out is that while Nagel is explicit in that this is a hard problem, perhaps unsolvable and certainly unique - certainly very different to conventional physics problems - he doesn't dismiss materialism either. 

Now I don't subscribe to materialism or physicalism, I think they're wrong-headed. But I find Nagel's attempts to at the very least say, "hang on a minute, this is tricky, sure, but the subjective nature of experience doesn't mean we can automatically deny materialism." And this is an important point. As always, those of us who fall on one side of the debate or the other ought to at least consider the opposite and try and defend it*. Nagel, I think (and I genuinely don't know if this was his intent or not) comes across as pleasingly neutral :

* There is something truly perverse about any philosopher with conviction.

It is useless to base the defence of materialism on any analysis of mental phenomena that fails to deal explicitly with their subjective character. For there is no reason to suppose that a reduction which seems plausible when no attempt is made to account for consciousness can be extended to include consciousness. Without some idea, therefore of what the subjective character of experience is, we cannot know what is required of a physicalist theory.

Which neither excludes nor endorses physicalism. It could be that the existence of subjective experience arises from something completely non-physical, but it could also be that we just don't understand enough about physical reality to say if that's the case. Indeed what grounds do we, physical beings, have for saying that our experiences are non-physical ?

To illustrate why the problem is so intractable, he remarks :

• Bats have a sense of sonar which we simply cannot imagine, which may well be nothing much like hearing at all. We cannot imagine entirely new states simply by pretending to add or subtract from our existing potential, any more than we could imagine new colours. We can imagine the behaviour of bats, but not how or why they think in the way they do. We are all trapped in Mary's Room.
• The reason why we cannot do this is due to hardware, not failure of reasoning. Bats are nothing special in this regard; we cannot imagine the subjective experience of human beings blind from birth any more than the congenitally blind could imagine vision, or any of us imagine four dimensions of space even though this is mathematically perfectly plausible. He says that "to deny the reality or logical significance of what we can never describe or understand is the crudest form of cognitive dissonance."

Neither of these points exclude physicalism. He makes the analogy of a caterpillar trapped in box which then pupates into a butterfly. Without seeing the transformation happen, we could still reasonably infer that the butterfly originated somehow from the caterpillar. Similarly for mental states : we know that they arise in response to physical phenomena, so although we don't know which particular observable neural process corresponds to, say, anger, we can nevertheless be reasonably certain that there is one. Maybe it's something we can already observe, maybe it's emergent from a suite of processes, maybe it's something we've yet to see (or indeed are ever capable of seeing). But the difficulty may not be with our understanding of the mind, but with our understanding of physical reality. There are no consciousness particles, but they might not be necessary.

I like this interpretation of materialism very much - at least, it's the best explanation of it I've heard yet. It certainly feels like subjective experience is manifestly different from physical fields, but how can we know this ? We clearly don't have full knowledge of physics, so perhaps it's foolish to presume we can rule out an objective origin of subjective experience*.

* Though I am reminded a little of Alan Dressler's comments on the non-importance of galaxy environment for evolution. Famous for quantifying how there's a marked change in galaxy type, with dense regions dominated by ellipticals and less dense regions by spirals and irregulars, he thinks that because the relation is weak it means environment isn't very important. Likewise Nagel clearly thinks that there is a strong subjective aspect to reality which can't be quantified, making it rather surprising when he says that actually maybe it somehow can.

The primary difficulty for Nagel appears to be descriptive. Those hardware limitations make it truly impossible for us to convey the nature of subjective experience to others. If I see an object which looks blue, the very best I can do is reproduce those viewing conditions to you and hope you experience the same thing I do. But there is absolutely no way I can be certain you're experiencing the same thing I am. 

As Nagel notes, even if I view the Mona Lisa and you find a tiny image of the painting somewhere in my brain, you still don't have any reason to equate this with the subjective experience of viewing it. I cannot describe even simple colours with pure words, you must have a reference of your own or it's meaningless. And while Nagel speculates that maybe such a framework for conveying qualia could be developed, he seems to accept how it's a total mystery how this could ever happen, and that it could ever go more than partway. Objective measurements, then, are ultimately distinct from subjective experience - ultimate in the extreme rather than emphatic sense. The two cannot be reconciled, at least, not with present knowledge.

Neutral monism certainly seems to offer the happiest compromise : there are no things, only stuff; our description of reality is literally just that - a set of descriptive labels. With that assumption it becomes altogether easier to accept that there could be some unknown singular substance that manifests itself differently, some unification that it might please believers to call God and atheists to call... I dunno, the Flying Spaghetti Monster, probably. I remind myself that my perspective as a tiny miniscule bunch of atoms offers me no special claim on the nature of reality any more than that of an amoeba or a being the size of a planet.... yet, I cannot help but shake myself from my reverie, scratch my nose, see the colours around me and think, "Nope, this is all a bit mad, I'm gonna stick with dualism, thanks."