Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cmcl2!yale!cs.yale.edu!blenko-tom
From: blenko-tom@CS.YALE.EDU (Tom Blenko)
Newsgroups: comp.ai
Subject: Re: What is a Symbol System?
Keywords: symbol manipulation, syntax, formality, semantics
Message-ID: <6932@cs.yale.edu>
Date: 29 Nov 89 04:06:58 GMT
References: <11640@phoenix.Princeton.EDU> <6170@cs.yale.edu> <11655@phoenix.Princeton.EDU> <6921@cs.yale.edu>
Sender: news@cs.yale.edu
Reply-To: blenko-tom@CS.YALE.EDU (Tom Blenko)
Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
Lines: 52

In article <6921@cs.yale.edu> mcdermott-drew@CS.YALE.EDU (Drew McDermott) writes:
|In article <11655@phoenix.Princeton.EDU> harnad@phoenix.Princeton.EDU (S. R. Harnad) writes:
|>
|>
|>mcdermott-drew@CS.YALE.EDU (Drew McDermott) of
|>Yale University Computer Science Dept asked:
|>
|>> Why is it necessary that a symbol system have a semantics in order to
|>> be a symbol system? I mean, you can define it any way you like, but
|>> then most AI programs wouldn't be symbol systems in your sense.
|>> 
|>I'd rather not define it any way I like. I'd rather pin people down on
|>a definition that won't keep slipping away, reducing all disagrements
|>about what symbol systems can and can't do to mere matters of
|>interpretation.
|> ...
|
|Which "people" need to be pinned down?  Fodor, I guess, who has a strong
|hypothesis about a Representational Theory of Meaning.
|
|But suppose someone believes "It's all algorithms," and not much more?
|He's willing to believe that intelligence involves an FFT here, some
|inverse dynamics there, a few mental models, maybe some neural nets,
|perhaps a theorem prover or two,....  His view is not completely vacuous
|(Searle thinks it's even false).  It might be a trifle eclectic for some
|philosophers, but so what?

I don't share Drew's disenchantment with semantic models, but I think
there is a more direct argument among his remarks: specifically, that
it isn't a particularly strong claim to say that an object of
discussion has "a semantics".  In fact, if we can agree on what the
object of discussion is, I can almost immediately give you a semantic
model -- or lots of semantic models, some of which will be good for
particular purposes and some of which will not. And it doesn't make any
Difference whether we are talking about axioms of FOPC, neural
networks, or wetware.

Richard Feynman had an entertaining anecdote in his biography about a
fellow with an abacus who challenged him to a "computing" contest.  He
quickly discovered that the fellow could do compute simple arithmetic
expressions as fast as Feynman could write them down. So he chose some
problems whose underlying numerical structure he understood, but which
it turned out that the other fellow, who simply knew a rote set of
procedures for evaluating expressions, didn't

Who had a semantic model in this instance? Both did, but different
models that were suited to different purposes.  I suspect that Harnad
had a particular sort of semantics in mind, but he is going to have to
work a lot harder to come up with his strawman (I don't believe it
exists).

	Tom


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