Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!gatech!bloom-beacon!husc6!diamond.bbn.com!aweinste From: aweinste@Diamond.BBN.COM (Anders Weinstein) Newsgroups: comp.ai Subject: Re: The symbol grounding problem Message-ID: <7204@diamond.BBN.COM> Date: Wed, 15-Jul-87 16:00:29 EDT Article-I.D.: diamond.7204 Posted: Wed Jul 15 16:00:29 1987 Date-Received: Fri, 17-Jul-87 07:23:24 EDT References: ... <6867@diamond.BBN.COM> <972@mind.UUCP> Reply-To: aweinste@Diamond.BBN.COM (Anders Weinstein) Distribution: world Organization: BBN Labs, Cambridge, MA Lines: 81 Summary: Philosophy's borders defended against the encroachments of psychology In a previous message, I was prompted by Stevan Harnad's postings to try to explain something I find very interesting, namely, why the psychology of categorical perception won't do much to illuminate the difficult question of how formal symbols should be semantically interpreted, i.e. what the symbols really *mean*. Harnad sent a long reply (message 972@mind.UUCP) explaining the nature of his approach in great detail. The upshot, I think, is that in spite of some of the rhetoric about "symbol grounding", Harnad's project is not really *attempting* to do any such thing. It merely aims to discover the mechanisms underlying certain recognition skills. Since this more modest aim was precisely what I was urging, I am satisfied that there is no major disagreement between us. I want to make clear that I am not here trying to pose any *objection* to Harnad's model considered as a bit of psychology. I am only trying to downplay its significance for philosophical issues. Remember that the traditional conception of "meanings" or "concepts" involves certain properties: for example, meanings are supposed to contain a criterion which determines the correct application of the term, in effect defining the metaphysical essence of the concept in question; they are supposed to serve as elementary constituents of more complex concepts and thoughts; and they are supposed to license analytic implications, such as "all bachelors are unmarried". Since none of these properties seem to be required of the representations in Harnad's theory, it is in a philosophical sense *not* a theory of "concepts" or "meanings" at all. As Harnad should be be happy to concede. But I want to emphasize again an important reason for this which Harnad seemed not to acknowledge. There is a vast difference between the quick, observational categorization that psychologists tend (rightly) to focus on and the processes involved in what might be called "conclusive" classification. This is the difference between the ability to recognize something as fish-like in, say, 500 milliseconds, and the ability to ascertain that something *really* is a fish and not, say, an aquatic mammal. Now the former quick and largely unconscious ability seems at least a plausible candidate for revealing fundamental cognitive mechanisms. The latter, however, may involve the full exercise of high-level cognition -- remember, conclusive classification can require *years* of experiment, discussion and debate, and potentially involves everything we know. The psychology of conclusive categorization does *not* deal with some specialized area of cognition -- it's just the psychology of all of science and human rationality, the cognitive scientist's Theory of Everything. And I don't expect to see such a thing any time soon. Confusion can result from losing sight of the boundary between these two domains, for results from the former do not carry over to the latter. And I think Harnad's model is only reasonably viewed as applying to the first of these. The rub is that it seems that the notion of *meaning* has more to do with what goes on in the second. Indeed, what I find most interesting in all this is the way recent philosophy suggests that concepts or meanings in the traditional sense are essentially *outside* the scope of forseeable psychology. Some other replies to Harnad: Although my discussion was informed by Quine's philosophy in its reference to "meaning holism", it was otherwise not all that Quinean, and I'm not sure that Quine's highly counter-intuitive views could be called "standard." Note also that I was *not* arguing from Quine's thesis of the indeterminacy of translation; nor did I bring up Putnam's Twin-Earth example. (Both of these arguments would be congenial to my points, but I think they're excessively weighty sledgehammers to wield in this context). The distinction between observational and "conclusive" classification, however, does bear in mind Putnam's points about the the non-necessity of stereotypical properties. I also don't think that philosophers have been looking for "the wrong thing in the wrong way." I think they have made a host of genuine discoveries about the nature of meaning -- you cite several in your list of issues you'd prefer to ignore. The only "failure" I mentioned was the inability to come up with necessary and sufficient definitions for almost anything. (Not at all, by the way, a mere failure of "introspection".) I *do* agree that the aims of philosophy are different than those of psychology. Indeed, because of this difference of goals, you shouldn't feel you have to argue *against* Quine or Putnam or even me. You merely have to explain why you are side-stepping those philosophical issues (as I think you have done). And the reason in brief is that philosophers are investigating the notion of meaning and you are not. Anders Weinstein BBN Labs