Sunday, October 17, 2010

Consciousness: the other horn of the dilemma in philosophy of mind

I take Turing’s thought experiment to be entirely persuasive, with the radical and happy outcome that, among other things, it reveals the old epistemological chestnut “the problem of other minds” to be a pseudoproblem (Wittgenstein emphasizes this). There is another famous gedanken-style argument in the philosophy of mind that I find equally persuasive, owing to John Searle: the Chinese Room Argument. I found both the Turing Test and the Chinese Room Argument to be rather fast and baffling at first, and then I went through a period of doubt and resistance, but I cannot find any argument that shows either of them to be fallacious or misapplied (and many, many have tried). I now feel certain that they are both correct. The only problem is that they are mutually contradictory.

Imagine, Searle asks, a person in a room. The room has a slot where people outside the room can enter printed notes and another slot where he can put out notes in response. This person cannot read or speak Chinese. He has two things: a large cache of Chinese characters (maybe he has a Chinese-character typewriter), and a set of instructions. The instructions are purely formal: for each Chinese character or set of characters that comes in to the room, there is specified a character or set of characters to be put out. Chinese-speakers write notes and put them into the room: “What is the capital of France?” say, or “What is your favorite food? Mine is chocolate.” or “I plan to vote for Obama, but my brother disagrees.” The person in the Chinese Room examines the characters, finds them in the instruction manual, and prints out the responding characters that are specified there. The instructions are such that the Chinese-speakers are satisfied that they are conversing with an intelligent being, one that knows something about geography and any number of other topics and can converse about food, politics, relatives and so on.

According to Turing, the Chinese-speakers (and everyone else outside the room) would have to conclude that the Chinese Room was intelligent. In fact the Chinese Room just is intelligent (no inference is necessary) since, on the operationalist view, “intelligence” consists of nothing more nor less than this kind of intelligent behavior; there is no question of being wrong here. On the contrary, Searle argues that the Chinese Room knows nothing. Neither the person in the Room nor the Room as a whole has any idea what the topic is, or even that there is a topic: not even that the characters mean anything at all. The Chinese Room is, according to Searle, a formal rule-governed symbol-manipulating device and nothing more, and as such it knows nothing at all, and nothing that knows nothing can be considered “intelligent.” A thing lacking all awareness is not an intelligent thing.

Searle’s specific target is computationalism, the view that (human) cognition is a form of computation, in other words that intelligent humans are formal rule-governed symbol-manipulating systems. He doesn’t think that an intelligent artifact is impossible, because he’s a materialist: he accepts that an artifact with the same relevant causal properties as a human body would have the same kind of intelligence. It’s just that a computer is not that artifact. A computer can have a data-base as full of symbolic representations (words, pictures) about Paris as you like, but it is only the human user who can grasp what the symbols represent. And what is that? Cheese shops full of hard parmesan and soft camembert, well-dressed people whizzing by on motor scooters, cigarette butts stuck in the metal grid floors of the Metro: a specific place full of sounds, smells, textures, tastes and scenes.

The taste of the wine, the smell of the cigarettes, the feeling that the well-dressed people don’t admire your ensemble: these are conscious experiences. Humans have them, computers do not. Only beings who have conscious experiences (who are, that is, conscious) can know what a symbol stands for, because “knowing” consists of an appreciation of the quality of the relevant experiences. A human doesn’t even have to have been to Paris to get some feel for the place; they can read about it on their computer screen! No amount of increase in the computational power of a mere formal rule-governed symbol-manipulating device will be sufficient for understanding absent this capacity for qualitative experience. This capacity is consciousness.

But how is it that consciousness is a metaphysical problem? Here is another famous gedanken-style argument, this one owed to Frank Jackson, which makes the metaphysical nature of the problem clear. Imagine Mary, a color-blind color-vision specialist. Mary is an expert on the science of color perception. This involves a great deal of scientific expertise: Mary knows about the physics of light, for example about how red light has a spiky amplitude and blue light a flat one; she knows about the light-absorbent and –reflective properties of surfaces; she understands the way the rods and cones on the back of the retina measure the amplitude of light and accordingly stimulate the optic nerve; she knows about the visual cortex and how the cells are arranged and connected there. Let’s say Mary is the world’s foremost color-vision specialist. Let’s even idealize Mary a little bit: let’s say that she is in possession of the complete and correct physical description and explanation of color vision, from the physics of light to the neurophysiology of perception. She knows all there is to know, and she’s got it all right.

Mary is color-blind. She has never seen a blue or red surface, only blacks, grays and whites. That is, she doesn’t know what colors look like. Sadly, she does not have the capacity for the relevant qualitative experience (I’ve always suspected that Mary has over-compensated for her disability in the pursuit of her chosen career). If this is right, then a complete and correct physical description and explanation of experience is lacking some information: what it is like to see colors (to use a phrase made famous by yet another exponent of the problem, Thomas Nagel). Now we have another putative mental “property,” and like the semantic property it appears to be unanalyzable into physical properties. There is even a noun, quale (singular of qualia), that denotes these qualitative feelings: the quale of this bite of chocolate I’m taking is this particular taste-sensation that constitutes my being conscious of the chocolate in my mouth. Conscious experience consists of qualia and qualia are not analyzable into, identifiable as, or reducible to physical properties.

Thus psychology cannot be naturalized. There is something called phenomenal description (the description of the quality of experience) that necessarily is always distinct from physical description. The study of experience qua experience is called phenomenology, but I will call the metaphysical problem, following the usage in contemporary philosophy of mind, “the problem of consciousness.” This is the subject of Chapter Three. There is a close connection between this problem as it is framed by contemporary philosophy of mind and the much older philosophical problem of the possibility of a radical difference between our experience of the world and the world as it actually is. In modern philosophy it is more common to put this as an epistemological problem (for example in the literature of skepticism). Both the English-language phenomenalists and the Continental phenomenologists of the early 20th century wanted to put metaphysics behind them, but I will maintain that progress here can only be made in the context of an explicitly metaphysical discussion. Nor would my conclusions be congenial to philosophers of that era: I will argue that the phenomenalists were in the grip of a disastrous misinterpretation of Hume and that phenomenology is impossible.

Like most people I tend to be drawn towards symmetry. Alas, Chapters Two and Three do not have symmetrical arguments. Whereas I break the problem of intentionality down into two constituent problems, the problem of representation and the problem of rationality, and offer positive theories to handle both, I will argue that the problem of consciousness is in fact a pseudoproblem and thus not amenable to (or in need of) any “theory” at all. Nonetheless even if one is persuaded, as I am, by the argument that the problem of consciousness is a pseudoproblem it turns out that there still remains something to say about metaphysics and consciousness and that discussion forms the second part of Chapter Three.

Philosophy of mind finds itself, at the beginning of the 21st century, to be at something of an impasse. For much of the 20th century operationalists had an agenda stable enough and productive enough that they were able to basically ignore the challenge of the phenomenologists, although the rejection of behaviorism as a popular psychology, after a long battle from Aldous Huxley’s iconic Brave New World through B. F. Skinner’s incendiary Beyond Freedom and Dignity, made the problem clear enough. (A crucial exception was Wittgenstein, but I will save that discussion for Chapter Three.) Gradually the dam broke and by the end of the 1980s thanks to Searle, Jackson, Nagel and others the post-“Analytic,” English-language philosophy of mind community acknowledged the problem of qualia as a central problem, and today one of the most thriving branches of the field, quite at home with the scientific neighbors in the area of “cognitive studies,” is “consciousness studies.” I will call those who take the problem seriously the “phenomenologists” although no doubt some will think that term comes with too much baggage; I ask the reader’s indulgence for the sake of exposition.

These new phenomenologists quickly set about demonstrating the inadequacy of functionalism and operationalist approaches in general as comprehensive theories of mind. For any qualitative experience (any quale) that appears to have a causal role in the production of behavior, the argument goes, one can conceive of a being with the functionally equivalent behavior but not the quale (a number of these “absent qualia” arguments, while mostly to the same point, are important enough to get their own discussion in Chapter Three). This might seem to be more of a problem for the advocates of phenomenology than it is for the advocates of operationalism but the opposite is true: if a functionally complete description and explanation of a person lacks any description or explanation of consciousness then functionalism is in the same position as Jackson’s Mary gedanken appears to put physicalism in general: it is not a complete theory of mind. In the literature this is often tagged as the “zombie” problem: the zombie is the allegedly conceivable functionally-complete but consciousness-lacking person.

The phenomenologists, for their part, have often accepted that the problem of consciousness does indeed thwart the naturalization of psychology, just as their older Continental namesakes did (although with considerably less enthusiasm). For example there is a well-developed line that a “property” dualism is inevitable, a kind of epistemological dualism that does not commit one to actual metaphysical dualism. I don’t think so: I think that metaphysical physicalism entails epistemological physicalism, on the grounds that that is the only possible significance of such a metaphysical assertion. There is a group that calls itself the “mysterians,” who argue that we just have to concede that there is no accounting for the relationship between the physical and the phenomenal. And one of the most noted writers on the topic in recent years, David Chalmers, had considerable success with his suggestion that metaphysical dualism is the right theory after all (admittedly the suggestion is made in a Berkelean spirit: we should just concede metaphysical dualism and move on). An exception to these various consuls of despair is Searle, and that is another discussion elaborated in Chapter Three. But with exceptions the phenomenologists find themselves with an apparent refutation of operationalist theories but without a coherent theory of their own.

The book you are reading is titled The Mind/Body Problems; the aim of the title is to draw your attention to the plural. The next section is, I think, straightforward, but it is one of the most important sections of the book.

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