Newsgroups: sci.logic,comp.ai.philosophy
From: rbj@campion.demon.co.uk (Roger Bishop Jones)
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!news.mathworks.com!hookup!swrinde!howland.reston.ans.net!news.sprintlink.net!demon!campion.demon.co.uk!rbj
Subject: Re: Expressibility (was "Penrose's new book)
References: <1994Oct26.172830.3987@oracorp.com> <1994Oct27.020638.28742@news.media.mit.edu> <783412036snz@campion.demon.co.uk> <1994Oct29.225104.8917@news.media.mit.edu>
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Date: Mon, 31 Oct 1994 06:29:30 +0000
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In article <1994Oct29.225104.8917@news.media.mit.edu>
           minsky@media.mit.edu "Marvin Minsky" writes:

> In article <783412036snz@campion.demon.co.uk> rbj@campion.demon.co.uk writes:
> >
> >Why should computer science students be suspicious of first order logic?
> 
> Simply because you cannot include heuristics in the form of advice
> about which kinds of assumptions of previous inferences ought or ought
> not be used for various sorts of problem-solving situations.  Perhaps
> I should have said "AI students" rather than CS students.  However, I
> regard AI as the part of CS that ought to push the frontiers of
> expressibility, etc.
> 

I don't go with your "cannot include heuristics" here.  Surely 1st order logic
is a "tabula rasa" (however its spelt).  Whatever you want to talk about
you can chose a 1st order language with suitable "non-logical" vocabulary and
go right ahead.  For many subject domains you won't be able to find a complete
axiomatisation, but that problem applies to other logics equally.

(I am speaking here as a philosopher rather than an engineer, I'm not
saying that there aren't any practical reasons for preferring a different
logic.)

-- 
Roger Jones
rbj@campion.demon.co.uk
