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From: rlr@pyuxd.UUCP (Rich Rosen)
Newsgroups: net.philosophy
Subject: Re: Sc--nce Attack (self-awareness)
Message-ID: <1888@pyuxd.UUCP>
Date: Wed, 16-Oct-85 22:18:12 EDT
Article-I.D.: pyuxd.1888
Posted: Wed Oct 16 22:18:12 1985
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>>Ie. maybe a Turing machine can simulate the brain, but ...

> OK, here is a question.
> My understanding is that Godel's incompleteness theorems prove
> (assuming the consistency of Arithmetic) that no Turing machine
> can possibly simulate the human mind.
> This is because for any particular Turing machine there are certain
> statements that the human mind can recognize as true (again with
> the consistency assumption), that the machine cannot recognize
> as true.
> 
> Does anyone dispute this?

I will.  Rudy Rucker offered a simplification of the Godel Theorem in
his book, Infinity and the Mind.  He described a Universal Truth Machine
(built up from a Mathematical Truth Machine, to a Scientific Truth Machine,
etc.)  He puts a proposition, "G", to the machine, that proposition being
"The UTM machine will never find this proposition G to be true."  What is
the UTM's answer?  Can't reach one (if it's smart enough).  If it says
"true", then it is in fact false, and of course vice versa.

A deathblow to the notion of machines being intelligent?  What if we
rephrased the proposition and asked it of Michael Ellis?  The new
proposition, G', would read "Michael Ellis will never say that this
proposition G' is true."  What will Michael's answer be?  Of course, Michael
can say anything he wants to say.  If he was being truthful (for instance,
if his life depending on his giving the right answer), he would be unable
to say either true or false (and thus he'd be in big trouble).  But he
has the option of (in other circumstances) lying, just saying true or
false because he feels like it.  Is it beyond the realm of possibility
for a machine to do the same thing:  to recognize the self-contradictory
nature of the sentence THE SAME WAY WE DO?  And answering "that proposition
cannot be decided", OR (even!) having the capacity of "lying"?  Of giving
the machine MOTIVATIONS for making such choices?

(Sorry for using Michael for this example.  I hope he's not burning up
saying "Norman, coordinate" at this moment.  But then, Michael's never
bothered much with such logic anyway. :-)
-- 
"I was walking down the street.  A man came up to me and asked me what was the
 capital of Bolivia.  I hesitated.  Three sailors jumped me.  The next thing I
 knew I was making chicken salad."
"I don't believe that for a minute.  Everyone knows the capital of Bolivia is
 La Paz."				Rich Rosen    pyuxd!rlr