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Article 2102 of comp.ai.philosophy:
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>From: fb0m+@andrew.cmu.edu (Franklin Boyle)
Newsgroups: comp.ai.philosophy
Subject: Re: Searle, again
Message-ID: <8dGDgay00Uh_I2nc1B@andrew.cmu.edu>
Date: 13 Dec 91 18:25:42 GMT
Organization: Cntr for Design of Educational Computing, Carnegie Mellon, Pittsburgh, PA
Lines: 44

Mark Rosenfelder writes:

>In article <4dFul6O00Uh7A37HQ7@andrew.cmu.edu> fb0m+@andrew.cmu.edu
(Franklin B
>oyle) writes:
>>There are two reasons algorithms, as manipulations of symbols, do not
>>refer to objects or states of affairs in the world: the first is that
>>the symbols physically do not in any way resemble the things to which 
>>we hold them to refer.  
> 
>How do you think our brains refer to things?  Do you think your conception
>of the word "cat" is a little bundle of neurons in the shape of a cat,
>or what?  
> 
>>The second is that even if they did resemble
>>the structures of external objects, the physical process of pattern 
>>matching does not transmit physical structure, hence, inputs to the
>>system (say from a camera) can only *trigger* further processing.  That
>>is, the matcher, because it structurally couples to the incoming pattern
>>can only output a signal that further change should occur.  But this signal
>>carries no structural information about the input -- it is merely a voltage
>>change.  Of course, you could set up the system so that the signal triggers 
> 
>Again, what do you think the nerves from the eye transmit?  How do the
>nerve impulses transmit "structural information"?  What makes you think
>(say) a digitizer doesn't do the same?
> 
>You must explain why your objection to the robot does not apply equally
>to the brain.

Impulses from single nerves do not transmit "structural information".  But
arrays of nerves do.  That is how there is a retinotopic mapping of the
visual field on the visual cortex.  There are no little photographs in the
brain, but my claim is that the structural variations of the input are
preserved and you don't get that kind of preservation in a pattern matching
system, which is what computers are (that is, the *physical* process of 
pattern matching, not functional.  Surely, functionally, we are also
pattern matching systems). The only way you can get structural information
into a computer is deliberately program it in or, in connectionist networks,
by feedback. This is because in both systems, structure is not 
transmitted.  And as I've argued in previous posts, feedback mechanisms do 
not seem plausible for higher level cognitive processing.

-Frank


