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From: JMC@SAIL.STANFORD.EDU (John McCarthy)
Newsgroups: comp.ai.digest
Subject: re: [Robert L. Causey : Natural Kinds]
Message-ID: <8707200505.AA05770@ucbvax.Berkeley.EDU>
Date: Sun, 19-Jul-87 02:15:00 EDT
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Posted: Sun Jul 19 02:15:00 1987
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[In reply to message from AI.CAUSEY@R20.UTEXAS.EDU sent Sat 18 Jul 87.]

I agree with Bob Causey's comments and agree that the open questions he
lists are unsolved and important.  I have one caveat.  The distinction
between nomological and functional kinds exists in sufficiently elaborate
mental structures, but I don't think that under 2 year olds make the
distinction, i.e. have different mechanisms for learning them.  For this
reason, it is an open question whether it should be a primary distinction
for robots.  In a small child's world, chairs are distinguished from other
objects by appearance, not by function.  Evidence: a child doesn't refer
to different appearing objects on which he can also sit as chairs.
Concession:  there may be such a category "sittable" in "mentalese", and
languages with such categories might be as easily learnable as English.
What saves the child from having to make the distinction between kinds
of kinds at an early age is that so many of the kinds in his life are
distinguishable from each other in many ways.  The child might indeed
be fooled by the different generations of calculator, but usually he's
lucky.

I hope to comment later on how robots should be programmed to identify
and use kinds.