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From: jharper@seismo.CSS.GOV@euroies.UUCP
Newsgroups: mod.ai
Subject: Re: logic in ai
Message-ID: <8702271342.AA28822@mcvax.cwi.nl>
Date: Fri, 27-Feb-87 07:46:54 EST
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Posted: Fri Feb 27 07:46:54 1987
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Reply-To: euroies!jharper (Jerry Harper)
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I think some useful distinction can be made between the use of _formalisms_
in AI and the use of logic(s).  The function of the latter with respect to a
series of inference rules and a particular domain of discourse is the 
characterization of truth and logical consequence.  The function of the
former on my own reading of AI literature concerned with NLP systems
seems to merely crystallize certain _intuitions_ a researcher may have
about the description and solution to a various problem. In some cases
these may conform to a logical calculus, in other cases they merely
appear to do so.  This is quite reasonable in a research context such as
AI provided one accepts that computational tractability and formal
rigour are different objectives served by methodological demands.
For instance, it would be impossible to build the model theory of
many logics used for semantic investigations of natural language into
a computational system.  Yet _doing_ semantics entails the use of
infinitary methodology once the model theory is based on possible
worlds.  Reinterpreting a semantic theory computationally is not
equivalent.  More fundamentally, it is the usage of the word _logic_
which is at issue.  With the plethora of logical calculi it makes
little sense to claim one uses _a lot of logic_ in ones work.  Indeed
if anyone has an uncontentious definition of modern logic please
forward it.