From: cam@castle.ed.ac.uk (Chris Malcolm)
Newsgroups: comp.ai.philosophy
Subject: Re: Grounding
Date: 11 Oct 92 22:31:09 GMT
Organization: Edinburgh University

In article <1asq47INNr9o@smaug.West.Sun.COM> dab@ism.isc.com (Dave Butterfield) writes:
>cam@castle.ed.ac.uk (Chris Malcolm) writes:
>>it is a commonplace illusion among philosophy students that they _are_
>>entirely symbolic in their cognitive functions, e.g., the common
>>belief that is impossible to think without thinking in (something
>>like) words.

>Why do you say that this is an illusion?  A symbol is anything
>that represents meaning.  What sort of thinking do you suppose
>occurs *without* the use of symbols?

I prefer a more restrictive definition of symbol -- that a symbol is
an _arbitrary_ label for a meaning. If the meaning of the symbol is
found in internal structures of the symbol which have isomorphisms to
features of the thing symbolised, then it is not symbolic, but
analogical.

We tend to think that our thinking consists essentially of what we
"observe" as our stream of consciousness, and our deliberate "clever"
thinking seems to consist of the application of special constraints
and tricks to this stream, e.g., mathematical problem solving. These
constraints and tricks are partly to do with making them communicable,
public, and verifiable. It is communicable public verifiable reasoning
that we have been successful in formalising, teaching, and more
recently, in automating, simply because it is essentially serial and
rule-governed. It's a trick we have taught ourselves to perform, a
momentous trick which separates us from the beasts, and facility with
this kind of artificial performance is what distinguishes clever men
from oafs. Clever men are apt to think it the most important, and
perhaps even the only kind of thinking.

That's only a small fraction of our thinking, however. There is no
doubt that the kinds of thinking involved in musical improvisation, in
crossing a busy road, and in walking bipedally without falling over,
have at least large components beyond the reach of conscious
attention, and that even those components within the span of conscious
attention often employ analogical representations, and are to that
extent not purely symbolic.

The mistaken importance clever men attached to clever symbolic
thinking is what makes the results of AI so apparently paradoxical:
the tasks that clever men considered the most difficult of all, such
as playing chess, solving mathematical problems, and diagnosing
diseases, have proved to be the easiest to automate; whereas what
every man can easily learn to do "without thinking", such as ride a
bicycle through traffic, are still far beyond the reach of both our
scientific understanding and the power of our computers.

It is a moot point whether we actually ever do think in words (or
word-like symbols), or whether these merely reflect -- sometimes well,
sometimes badly -- the activities of preconscious nonsymbolic thinking
processes.
-- 
Chris Malcolm    cam@uk.ac.ed.aifh          +44 (0)31 650 3085
Department of Artificial Intelligence,    Edinburgh University
5 Forrest Hill, Edinburgh, EH1 2QL, UK                DoD #205