Bertrand Russell's The Analysis of Matter has had a resurgence of interest in recent years, both among philosophers of science interested in structural realism, and among philosophers of mind interested in the mind-body problem. Russell's basic idea that science characterizes the physical world in terms of its structure but not in terms of its intrinsic nature has seemed to some philosophers (Russell himself, and more recently Grover Maxwell, Michael Lockwood, and me, among others) to leave the door open to a close tie between the unknown intrinsic properties at the basis of physics and consciousness itself. This leads to the view that I have called Russellian monism (or type-F monism, in "Consciousness and the Place in Nature").
At the same time, Russell's structuralism suffers from a well-known difficulty, pointed out in 1928 by the mathematician M.H.A. Newman in "Mr. Russell's 'Causal Theory of Perception'" (JSTOR link), and revived in a 1985 article by Demopoulos and Friedman. A purely structural description of the world, saying that there exists a relation under which entities in the world are related with a certain structure, can be satisfied by any set of the appropriate cardinality, by defining an appropriate relation on that set. So this sort of purely structural description seems near-vacuous. Some philosophers take this to be a devastating problem for structuralism (e.g. Michael Friedman raises it as a deathknell for Carnap's Aufbau), while others (e.g. Putnam in his model-theoretic argument) use it to raise problems about realism and reference.
I received an interesting e-mail from Moises Macias, an undergraduate at the National Autonomous University of Mexico, asking how one can reconcile this problem for structuralism with its popularity in the philosophy of mind. This led to some useful correspondence. Since this is an issue that quite often comes up in discussion, and it's one of my favorite issues, I thought I'd post some of the correspondence here (after the fold, with text from Moises indented).
How come if Newman's criticism is so devastating then so many arguments and trends in contemporary philosophy of mind (Lockwood, Chalmers, Maxwell) start off from Russell's argument (that physics tells us only about the structure of the world, the dispositional properties of its objects and not of its internal properties) to the conclusion that perhaps Russell was right in claiming that we have knowledge of the intrinsic properties of at least one physical system, namely the brain? Lockwood, Maxwell, Stoljar, Nagel, Galen Strawson, Unger and you all present pretty good arguments for at least considering seriously the Russellian position, a position which, if I understand correctly, could only work if Newman's argument is not as destructive as many other philosophers claim it to be. Also, if memory serves me right, van Fraassen has an interesting and somewhat sympathetic discussion of structural realism in its own right which can be found in his web page. How come no one, as far as I know, has examined Newman's arguments in the discussions concerning Russellian theories of the mind, and vice versa?
Good question. I'm sympathetic with Newman's argument, but I don't think it applies to the sort of view I advocate. Newman's argument applies against "pure structuralism", where every term in the theory is in effect defined structurally, and where there are no primitives that get their meaning independently. The view that Lockwood, Maxwell, and I advocate is not nearly that strong. The claim is that terms like "mass", "charge", etc, are defined structurally. But there may be other non-structurally-defined terms. E.g. "cause", "law", "experience", and perhaps "space" and "time" (though I'm doubtful about those two). Some terms like these will be primitives, referring to causation, lawhood, experiences, independently of any structural role they play. That will be enough to avoid Newman's argument and to pin down the reference of the other terms. Note that this is broadly in the spirit of Russell's own reply to Newman, where he accepted that certain notions (I recall that he said spatiotemporal copunctuality) would have to be primitive and not structurally defined.
Returning to the problem, how can one determine which terms will be defined structurally and which ones will be primitive? I suppose mass, charge, etc, must necessarily be defined structurally taking into account the roles they fulfill in physics, but why should lawhood or causation be defined that way? And would defining them that way would require of them something akin to an ontologically platonic status (like taking the objects of set theory, for instance, as fundamental)? And why is such a defense to Newman's argument effective? All of these questions appear to me to be very difficult, and was hoping perhaps you would comment.
I think the general motivations for the Russellian view on the mind-body problem are weaker than the motivations for pure structuralism. For the Russellian view, you just need the idea that basic physical terms are theoretical terms, characterizing physical properties as the entities that play certain roles without specifying the intrinsic nature of those entities. That opens the door for type-F monism and the like. But it certainly doesn't force one to general structuralism. For that, one would need the much stronger claim that all terms are theoretical terms, or something like that. I don't see any reason to accept that, and certainly you can't get the stronger claim from the weaker claim.
For example, if one takes a Ramsey-sentence approach to theoretical terms, there will always be O-terms in which the sentences are cast. If one thought one could continue eliminating the O-terms indefinitely with more Ramsey sentences (yielding "global Ramsification"), one would eventually arrive at a version of Newman's problem. But one might instead take this threat of vacuity as a good reason to deny that all terms are theoretical terms. And in fact, there isn't any obvious reason to think that all O-terms in typical scientific theories will themselves be theoretical terms and therefore eliminable. One can't plausibly eliminate logical/mathematical or experiential terms in this way, for example. And presumably there can be other O-terms too, such as "law" and "cause", and so on.
The question of what are the fundamental O-terms is very interesting. On my view it is one of the deepest questions in philosophy. I have discussed it briefly in various places -- e.g. in Powerpoint presentations on primitive concepts and on terminological disputes, and in much work in progress on the topic. On my view, the best candidates include phenomenal, logical, mathematical, and nomic concepts. Some would add spatiotemporal concepts, but not me.
Then there is the question you raised of what is special about the primitive concepts. I don't see why these must lead to ontological platonism. But arguably they require that we have some sort of non-derivative grasp of the concept, whereas the other concepts allow a grasp that derives from our grasp of these primitive concepts. Just what that non-derivative grasp consists in is unclear. One possibility is the Russellian idea of acquaintance in experience, but maybe there are others. That depends very much on how one thinks about concepts and intentionality in general. For my part I think this is another of the deepest questions in philosophy.
I don't think one needs to answer these latter questions to reply to Newman's argument. The argument is only an argument against pure structuralism. One can respond by denying pure structuralism. Perhaps there is some further problem for the denial of pure structuralism, but that problem will be independent of Newman's argument. But of course the question of the status of primitive concepts is of enormous independent interest.