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From: jmc@Gang-of-Four.usenet (John McCarthy)
Newsgroups: comp.ai.philosophy
Subject: Re: Reasoning Paradigms
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Date: 9 Oct 90 22:23:35 GMT
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In-Reply-To: petersja@debussy.cs.colostate.edu's message of 9 Oct 90 14:39:55 GMT

In article <10081@ccncsu.ColoState.EDU> petersja@debussy.cs.colostate.edu (james peterson) writes:

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   From: petersja@debussy.cs.colostate.edu (james peterson)
   Newsgroups: comp.ai.philosophy
   Date: 9 Oct 90 14:39:55 GMT
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   In article <JMC.90Oct8083235@Gang-of-Four.usenet> jmc@Gang-of-Four.usenet (John McCarthy) writes:

   >grounding is an oversimplified notion.  The human ability to do logic
   >developed from and still uses processes that can be called reasoning
   >but don't correspond to logic.  These processes are inaccurate in
   >unnecessary and inconvenient ways.  These inaccurate human processes did
   >form a desire to develop accurate reasoning processes, i.e. logic.

   What I am interested in is the nature of these "processes that can be called
   reasoning but don't correspond to logic" -- When you say "don't correspond"
   are you implying that they are irreducible to logical reasoning (I suspect you
   aren't)?  And these "inaccurate processes," are they actually instantiations
   of formal rule manipulation at a lower level of description?  Put another
   way, are they Turing computable?


   >
   >We can make an analogy with the fact that we can write an interpreter
   >for any good programming language in any another.  We can talk about
   >logic in ordinary language, and we can formalize ordinary language and
   >reasoning in logic.

   In "formalizing ordinary language" is there a residue that escapes
   formalization?

I don't understand human reasoning very well and neither (I think)
does anyone else.  However, there is no evidence that the basic
human reasoning processes correspond to what humans invented
(i.e. logic) in our attempt to get a more rational and explicit
reasoning process.  When we understand them better, I believe
human reasoning processes will be formalizable in logic at one
remove, e.g. there might be a formula

human-believes(person,p) &  human-believes(person,implies(p,q))
  & foo(person,p,q) =>  human-believes(person,q).

This asserts that humans do modus ponens with a qualification
expressed by  foo(person,p,q).