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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)
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Organization: BBN Labs, Cambridge, MA
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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