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From: harnad@mind.UUCP
Newsgroups: comp.ai,comp.cog-eng
Subject: Re: The symbol grounding problem
Message-ID: <786@mind.UUCP>
Date: Thu, 28-May-87 01:46:28 EDT
Article-I.D.: mind.786
Posted: Thu May 28 01:46:28 1987
Date-Received: Fri, 29-May-87 04:44:04 EDT
References: <764@mind.UUCP> <768@mind.UUCP> <770@mind.UUCP> <6174@diamond.BBN.COM>
Organization: Cognitive Science, Princeton University
Lines: 29
Keywords: icons, categories, symbols, grounding
Xref: utgpu comp.ai:424 comp.cog-eng:98
Summary: Physical isomorphism is captured by physical invertibility


Anders Weinstein of BBN wrote:

>	a point that I thought was clearly made in our earlier
>	discussion of the A/D distinction: loss of information, i.e.
>	non-invertibility, is neither a necessary nor sufficient condition for 
>	analog to digital transformation.

The only point that seems to have been clearly made in the sizable discussion
of the A/D distinction on the Net last year (to my mind, at least) was that no
A/D distinction could be agreed upon that would meet the needs and
interests of all of the serious proponents and that perhaps there was
an element of incoherence in all but the most technical and restricted
of signal-analytic candidates.

In the discussion to which you refer above (a 3-level bottom-up model
for grounding symbolic representations in nonsymbolic -- iconic and
categorical -- representions) the issue was not the A/D
transformation but A/A transformations: isomorphic copies of the
sensory surfaces. These are the iconic representations. So whereas
physical invertibility may not have been more successful than any of
the other candidates in mapping out a universally acceptable criterion
for the A/D distinction, it is not clear that it can be faulted as a
criterion for physical isomorphism.
-- 

Stevan Harnad                                  (609) - 921 7771
{bellcore, psuvax1, seismo, rutgers, packard}  !princeton!mind!harnad
harnad%mind@princeton.csnet       harnad@mind.Princeton.EDU