Gerardo Primero, a psychologist in Buenas Aires, has been corresponding with me via e-mail. He is studying Wittgenstein and wanted to talk about Bennett and Hacker's 2003 book Philosophical Foundations of Neuroscience. That book takes a Wittgensteinian approach (P. M. S. Hacker is one of the leading philosophical interpreters of Wittgenstein) and builds an argument that a great deal of cognitive studies makes some version of the "mereological fallacy," the fallacy of attributing to the parts of a thing properties that are had only by the whole. Specifically "persons," who are full embodied beings, think, dream, desire, imagine, and so forth, whereas much philosophical psychology attributes these intentional states to brains, to consciousness, to memory, and so forth. The idea is that just as I eat lunch, not my stomach, so too I think about the election, vs. my brain. Note that if this turns out to be right, that psychological predicates are applied to persons and not to brain states, then the metaphysical problem about how the physical properties of the nervous system "map on" to the semantic properties of the representations may be shown to be a pseudoproblem, in that intentional psychological descriptions just aren't descriptions of states of the brain. Mind does not necessarily = brain.
Let me quote a little from Gerardo's e-mail from Sunday: "I'm not convinced by Hacker's arguments....The problem with the 'mereological fallacy' is not that applying psychological terms to parts 'has no sense': it has sense, but it's scientifically unsound...While my argument is epistemic ("that's not a valid scientific explanation"), Hacker's argument is semantic ("that has no meaning at all").
There are a lot of directions we could go with this, but since Gerardo seemed to approach me for maybe a "philosopher's opinion," I'll talk some basic metaphysics and epistemology this afternoon. The issue is metaphysical, to my eye: there is a language about "properties," and so we want to get clear on what properties are, because it looks like we would need to do that to understand how the brain works (properties are causal). Specifically the "property" of interest in terms of the mind/body problem is the "intentional/semantic property." What is this? That bears some discussion, but note a basic issue: if you think that the semantic property is a property, but it's not a physical property, then you have signed on to some kind of metaphysical dualism. Descartes thought this way. He thought that any physical thing, being ultimately a mental representation, had the property of dubitability (could be unreal, an illusion), whereas the fact of thinking (of a "thinking substance") was indubitable, and this is one of his arguments for metaphysical dualism (sometimes called "substance dualism"). Disparate properties, disparate things. Which is fine, maybe, but recognize the committments that come with such a view: a) there are "things" that exist that are not part of the physical universe, and b) therefore, in this example of the more general metaphysical point, scientific psychology is impossible. I don't buy that. That is, I think that humans are part of physical nature through-and-through. And if "physicalism" means anything, it's got to mean that everything about humans that we can "explain" (whatever explanation is) we can explain in physical terms (just like the rest of nature). So a naturalist like myself has two options: 1) Try to understand "mental representation" and thus symbols and meaning in general in some kind of physical terms, or 2) try to eliminate representational content from the model of mind.
So, as to Gerard's distinction between "meaningful" and "explanatory," I would say that physicalists (we could here say materialists or naturalists, I'm not making any fine distinction) who are eliminativists (like Wittgenstein and Skinner) think that to the extent that "meaning" is not the same thing as "causal power" there isn't any such thing. Think of a behavioristic, anthropological account of the development of speech: the latter-day "semantics" of the words emerged out of the functional role of making that sound. It isn't true that all words function in the same way (that is, as symbols). This is what Wittgenstein means with the analogy of the locomotive controls: they all fit the human hand, but one opens a valve, one puts on a brake, etc.; it is a mistake to try to explain them all the same way.
If you can't explain the "mental" property without including something "mental" in the explanation, then you haven't explained mind. An "explanation" of mind would be the story of how semantic properties emerged from simpler, non-semantic properties. Mind from no-mind. So a problem with representations is that they already assume mind. Semantic content needs an interpreter. Or, the story about how something came to "mean" something can't already assume that "meaningfulness" exists - if you have to do that, you haven't succeeded in naturalizing the concept of "meaning."
There is a contingent who want to develop a natural theory of information. I would recommend starting with Fred Dretske's Knowledge and the Flow of Information. For myself, at this point I feel pretty convinced that there can't be any such thing as mental content, at all. Just wrong, root and branch. But note that there is a representational vogue underway amongst the cognitive scientists (or was two years ago).
Looked at this way, one can see that the problem with attributing mental states to brains isn't, I wouldn't say, meaningful but wrong (as Gerardo argues), but in fact not meaningful. They are pseudoexplanations because they don't turn out to even potentially explain anything: they're not even wrong. "When I remember her face, I have an image of her face." "I just gave myself a dollar." Both examples of the same mistake.
Finally for today, Gerardo wanted a little more on Wittgenstein vs. Moore. Moore tried to argue from "usage," that is, he argued that the claim "I know I have a hand" was a paradigmatic case of knowledge. Wittgenstein objected (in On Certainty) that there was no ordinary circumstance in which holding up one's hand and saying, "I know I have a hand" could have any purpose. W.'s point was that Moore made the mistake of continuing to play the game that was the cause of the confusion in the first place. In fact I neither know nor do not know whether I have a body; that's not really an example of a situation where the verb "to know" can serve any function.