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From: rlw@philabs.philips.COM (Richard Wexelblat)
Newsgroups: comp.ai.digest
Subject: Re: Natural Kinds
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Date: Tue, 21-Jul-87 12:56:08 EDT
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Posted: Tue Jul 21 12:56:08 1987
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In article <8707161942.AA13065@nrl-css.ARPA> mclean@NRL-CSS.ARPA
(John McLean) writes:

>However, I think the issue being raised about recognizing penguins,
>chairs, etc. goes back to Wittgenstein's _Philosophical_Investigations_:

Actually, the particular section chosen is a bit too terse.  Here is more
context:

   Consider, for example the proceedings that we call `games.'  I mean board-
games, card-games, ball-games, Olympic games, and so on.  What is common to
them all?--Don't say:  ``There must be something common, or they would not be
called `games' ''--but look and see whether there is anything common to all.
--For if you look at them you will not see something that is common to all,
but similarities, relationships, and a whole series of them at that ...  a
complicated network of similarities overlapping and criss-crossing; sometimes
overall similarities, sometimes similarities of detail.
   I can think of no better expression to characterize these similarities
than ``family resemblances''; for the various resemblances between the
members of a family: build, features, colour of eyes, gait, temperament,
etc.  etc. overlap and criss-cross in the same way.--And I shall say: `games'
form a family.

                                   * * *

This sort of argument came up in a project on conceptual design tools a few
years ago in attempting to answer the question:  ``What is a design and how
do you know when you have one?''  We attempted to answer the question and got
into the question of subjective classifications of architecture.  What is a
``ranch'' or ``colonial'' house?  If you can get a definition that will
satisfy a homebuyer, you are in the wrong business.

                                   * * *

Gratis, here are two amusing epigrams from W's Notebooks, 1914-1916:

	There can never be surprises in logic.
		  ~~~~~

	One of the most difficult of the philosopher's tasks is to
	find out where the shoe pinches.