It's been two months since I posted anything here, which is not how it was supposed to go. I have some excuses: replies to three papers at two recent philosophy conferences, a lack of breaking news on the cog sci front, and some personal stuff that I won't get into. Anyway, the last of the conference papers was concerned with a relatively recent paper by Paul Churchland, in which he argues for the "identity" of color "qualia" (an obnoxious Latinate neologism that philosophers use to refer to our mental experience of colors) with "cone cell coding triplets" or "vectors" - an analytic description of how the eye reacts on the cellular level to light of various wavelengths. Churchland further asserts that based on this analysis he can make certain predictions about our color experience in unusual cases, a feat that, according to him, is usually assumed to be beyond the power of materialist identity theories. That is the main point here; the identity of (a) the experience, and (b) the biochemical basis of the reaction, is said to not only account for ordinary experiences like seeing red, but for experiences which most people have not had. Churchland describes how to produce such experiences and provides various full-color diagrams to assist. The predictive power of the theory allegedly shows that the qualia-coding vector relationship is not a mere correlation but an actual identity.
It is not impossible that some philosophers have carelessly suggested that materialism cannot be true because it cannot make predictions about experience. But to rest the case against materialism on this narrow basis is a very bad idea, for the simple reason that there are straightforward and well known areas in which knowledge of the physical structure of the body allows you to make specific phenomenological predictions. For example, recently it was discovered that glial cells, which make up much of the central nervous system, contribute to severe or chronic pain by stimulating the pain-transmitting neurons. Prediction: find a drug that deactivates the glial cells, and with or without more traditional pain-relief methodologies (e.g., those which interfere with the transmission of signals across nerve synapses or attempt to freeze the nerve itself) the patient will feel less pain. There is a perfectly good phenomenological prediction from neurological facts.
And there are even easier cases. We know that the lens of the eye delivers an inverted image, which is subsequently righted by the brain. This suggests that our brains, without our conscious effort, favor a perspective that places our heads above our feet. (It is also possible that it is simply hard-wired to invert the image 180 degrees, but for various reasons that theory does not hold water.) Prediction: make someone wear inverting glasses, and they will see un upside down image at first (the brain inverts it out of habit), but eventually the brain will turn it right side up. It works!
And it gets even easier. After all, there were times long ago when we did not know anything about the internal structure of sense organs. Our auditory capabilities rest on the action of thousands of tiny receptors lodged in hair cells in the Organ of Corti, part of the cochlea of the inner ear. Prediction: dull the function of these receptors and and the subject will experience a loss of hearing. Wow, another phenomenological prediction. I'm sure you could go hog wild with this. Poke your left eye out and you will see in diminished perspective, an amazing prediction in itself. Practice seeing through one eye for a long time and your sense of perspective should increase. Such predictions differ a lot from an example that Churchland presents in another context, that trained musicians "hear" a piece differently than average audiences. That is also a predictable phenomenological fact, but it involves a change in the mental software, through accustomization and training, and does not obviously involve any sensual change. To see a new color or to have fewer distinct sounds reach the brain from the cochlea are sensual changes; to hear more deeply those sounds that do reach the ear, to organize them more efficiently and recognize more relationships between is not a sensual change but an intellectual one that we might metaphorically characterize as "hearing more than others". In fact musicians hear the same thing others hear but understand what they hear in a more lucid way. The sensual phenomena I have mentioned are actual changes in what reaches the brain for processing or in processing at a subliminal level, and do not depend on how we train ourselves to organize the information we receive.
I admit that my predictions are not very interesting; they operate at a more macro level than Churchland's strange color qualia, though not as macro as the following: cut out someone's tongue and they won't taste much. That's about like: cut out someone's brain and they won't think much. That may sound pretty obvious, but it wasn't always. Churchland is playing on the fact that intimate knowledge of how vision works is a relatively recent and still growing science. Thus it sounds like quite an amazing feat that he should be able to "predict" color "qualia".
But actually, although his predictions are more refined than mine, digging deeper into more subtle properties of the visual system, they are no more predictions of "qualia" than the general statement: interfere with some physical property of a sensory apparatus and you will change the sensations experienced by the subject. Refining this down to a specific phenomenological experience does not get closer to predicting "qualia", it merely makes a more specific prediction based on a fairly well fleshed out physical theory. It is roughly at the level of first discovering certain facts about the eye and then discovering that those facts are consistent with seeing a green after-image when exposed to a flashbulb. "I predict a green qual!" Okay, that's a little better than "I predict the stock market with crash - some time..." But it doesn't really do much for materialism. (And I'm not even talking about "eliminative" materialism here, which I said I'd refuse to take seriously, just the more typical materialist identification of experience with physical facts.)
Why? We could gloss Churchland's prediction as follows: "I predict that if you look at this in the right way you will have that experience that is commonly understood to be going on when a person utters the words, 'I see green'". And what is that? Just the very thing that non-materialists bring up as an "explanatory gap". Churchland can't predict we will have particular qualia because he doesn't have even so much as a theory as to what the relationship is between qualia and their scientific background. He seems to think that a correlation which has predictive accuracy is eo ipso an identity relation. But this is just another brain scam. One might say: qualia are a suspect kind of entity anyway, so why should I need a theory to account for them? Fine, but what you can't say is: these qualia you talk about, they just are these coding vectors, and then act like you've explained qualia. For example, suppose you were to say: these UFO's you talk about, they just are marsh gas. Okay, you've explained away UFO's. But you surely haven't explained UFO's. You've submitted the thought: until and unless you give me some specific physical evidence that there are these things, "UFO's", that cannot be explained by any other consistent set of physical facts except that secret aircraft controlled by animate beings are navigating our skies, I deny that UFO's exist as a category of object requiring independent explanation. Similarly, one can say: I can explain everything there is to explain about sensation without reference to "qualia", so why should I be obliged to give you a separate explanation of them? But that is not what is being offered. Rather, we are told, color qualia exist; they are cone cell coding vectors.
"Laughter exists; it is... [insert physical description of lung contractions and facial expressions]"
"Orgasm exists; it is... [insert physical descriptions of male or female anatomical changes during orgasm]"
"Aesthetic appreciation exists; it is... [insert data from brain scans of people listening to Mozart]"
"Religious rapture exists; it is... [insert data from brain scans of people talking in tongues]" (this has actually been studied, by the way)
When is Churchland going to wake up and smell the coffee? I'm not sure, but I don't think we should test it by asking him whether he's awake or not; better check his brain scan and let him know. Then do an EEG and see if he's smelling the coffee. With sufficient training he could be taught to look at the EEG and say, "Why, I was smelling coffee!" (This is the flip side of Churchland's utopia, in which we are all so well-informed about cognitive facts that introspection itself becomes a recognition of coding vectors and the like.) Now for the tricky part: turn off the switch in his brain that produces the coffee-smelling qual, and tell him that every morning, rather than having that phenomenological version of the sensation, he will recognize the coffee smell intellectually and be shown a copy of his EEG. And similarly, one by one, for all his other qualia.
Don't say: well, he doesn't deny these qualia exist, after all; he just thinks they are identical to blah-blah-blah... If he thinks they are identical to blah-blah-blah then he should not object in the least if we can produce blah-blah-blah without those illusory folk-psychological phenomena we think are the essence of the matter. So, on with the experiment. Where do you think he will balk? When we offer to substitute a table of coding vectors for the visual quals of his garden in springtime? An EEG for the taste of grilled tuna? Maybe a CAT scan of soft tissue changes rather than the experience of orgasm? I'd really like to know just how far he is willing to go with this. Would he wear one of those virtual reality visors, having in the program only charts and graphs and other indicators of brain and body function? Maybe Churchland is the only one among us who really understands how to have fun. Personally, I'll keep my red roses, my grilled tuna taste, and... the other stuff, thanks.