From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.ecf!utgpu!cs.utexas.edu!uunet!pipex!ibmpcug!ibmpcug!slxsys!uknet!edcastle!cam Sun May 31 19:04:40 EDT 1992
Article 5963 of comp.ai.philosophy:
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>From: cam@castle.ed.ac.uk (Chris Malcolm)
Newsgroups: comp.ai.philosophy
Subject: Re: Grounding: Real vs. Virtual (formerly "on meaning")
Keywords: symbol, analog, Turing Test, robotics
Message-ID: <21988@castle.ed.ac.uk>
Date: 28 May 92 21:42:36 GMT
References: <1992May23.141738.14114@news.media.mit.edu> <21813@castle.ed.ac.uk> <1992May25.202001.7388@psych.toronto.edu>
Organization: Edinburgh University
Lines: 49

In article <1992May25.202001.7388@psych.toronto.edu> christo@psych.toronto.edu (Christopher Green) writes:
>In article <21813@castle.ed.ac.uk> cam@castle.ed.ac.uk (Chris Malcolm) writes:

>>When proto-humans were subject to fierce evolutionary pressure to become
>>smarter -- and the speed with which our large brain evolved suggests
>>that this pressure was fierce [...]

>This is a very poor evolutionary inference. These sorts of just-so stories
>just aren't borne out by much of the paleontological data. 

Very few palaeontologists now doubt that a) one of the last major
evolutionary change suffered by humans was the enlargement of the
brain, and b) that this developement took place unusually rapidly.
Your mention of "palaeontology" does make me wonder, however, whether
you have noticed that palaeontology is no longer the pace-maker in the
chronology of human evolution.

>Evidence is that
>when "evolutionary pressure" is put on creatures, they almost always die off,
>and their niche is filled by another species better suited to the new 
>environment.

Quite so, they usually do, but not always. The exceptions happen in
circumstances where other candidates are not available. 

>Check outNiles Eldredge's _Time frames_ or Robert Bakker's
>_Dinosaur heresies_ for easily digestible accounts.  Look to Eldredge's
>_Macroevoutionary dynamics_ for a more sophisticated description.

It seems that it is you who are in need of a more sophisticated
description. From the premise that evolutionary pressure _usually_
leads to extinction and replacement you deduce that it cannot fail to
do so; and you use this odd induction to contradict my quite ordinary
(in evolutionary speculation) supposition that an observedly unusually
rapid change implied an unusually strong selective pressure.

Quite apart from that, you have entirely failed to notice that my
argument does not depend in the slightest on this supposition of
_strong_ pressure; that was simply a by-the-way remark. My argument
-- which you dismiss as a "just-so" story, works just as well if the
pressure was normal, or even weak -- it just requires that some
selective pressure existed.

I have rarely been subjected to such a half-baked and irrelevant
attack! Care to try again?
-- 
Chris Malcolm    cam@uk.ac.ed.aifh          +44 (0)31 650 3085
Department of Artificial Intelligence,    Edinburgh University
5 Forrest Hill, Edinburgh, EH1 2QL, UK                DoD #205


