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From: aweinste@Diamond.BBN.COM (Anders Weinstein)
Newsgroups: comp.ai,comp.cog-eng
Subject: Re: The symbol grounding problem
Message-ID: <6670@diamond.BBN.COM>
Date: Thu, 18-Jun-87 14:26:23 EDT
Article-I.D.: diamond.6670
Posted: Thu Jun 18 14:26:23 1987
Date-Received: Sun, 21-Jun-87 14:03:04 EDT
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Reply-To: aweinste@Diamond.BBN.COM (Anders Weinstein)
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In article <861@mind.UUCP> harnad@mind.UUCP (Stevan Harnad) writes:
>                                   The atomic terms of which they were
>composed would be the labels of categories in the above sense, and hence they
>would be grounded in and constrained by the nonsymbolic representations.
>They would preserve relations not just in virtue of their syntactic
>form, as mediated by an interpretation; their meanings would be "fixed"
>by their causal connections with the nonsymbolic representations that
>ground their atoms.

I don't know how significant this is for your theory, but I think it's worth
emphasizing that the *semantic* meaning  of a symbol is still left largely
unconstrained even after you take account of it's "grounding" in perceptual
categorization.  This is because what matters for intentional content is not
the objective property in the world that's being detected, but rather how the
subject *conceives* of that external property, a far more slippery notion.

This point is emphasized in a different context in the Churchland's BBS reply
to Drestke's "Knowledge and the Flow of Information." To paraphrase one of
their examples: primitive people may be able to reliably categorize certain
large-scale atmospheric electrical discharges; nevertheless, the semantic
content of their corresponding states might be "Angry gods nearby" or some
such. Indeed, by varying their factual beliefs we could invent cases where
the semantic content of these states is just about anything you please.
Semantic content is a holistic matter.

Another well-known obstacle to moving from an objective to an intentional
description is that the latter contains an essentially normative component,
in that we must make some distinction between correct and erroneous
classification. For example, we'd probably like to say that a frog has a
fly-detector which is sometimes wrong, rather than a "moving-spot-against-a-
fixed-background" detector which is infallible. Again, this distinction seems
to depend on fuzzy considerations about the purpose or functional role of the
concept in question.

Some of the things you say also suggest that you're attempting to resuscitate
a form of classical empricist sensory atomism, where the "atomic" symbols
refer to sensory categories acquired "by acquaintance" and the meaning of
complex symbols is built up from the atoms "by description". This approach
has an honorable history in philsophy; unfortunately, no one has ever been
able to make it work. In addition to the above considerations, the main
problems seem to be: first, that no principled distinction can be made
between the simple sensory concepts and the complex "theoretical" ones; and
second, that very little that is interesting can be explicitly defined in
sensory terms (try, for example, "chair").

I realize the above considerations may not be relevant to your program -- I
just can't tell to what extent you expect it to shed any light on the problem
of explaining semantic content in naturalistic terms. In any case, I think
it's important to understand why this fundamental problem remains largely
untouched by such theories.

Anders Weinstein
BBN Labs