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From: erich@eecs.cs.pdx.edu (Erich Stefan Boleyn)
Newsgroups: comp.ai.philosophy
Subject: Re: Introspection
Message-ID: <1663@pdxgate.UUCP>
Date: 18 Feb 91 23:39:18 GMT
References: <1991Feb4.224101.18846@watdragon.waterloo.edu> <1574@pdxgate.UUCP> <9550@latcs1.oz.au>
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stephens@latcs1.oz.au (Philip J Stephens) writes:


>Michel P. Devine writes:

>>I should be careful to point out that I do not repudiate the machine
>>model in toto, but that I consider it incomplete.  It is true that it is 
>>possible to assign specialized functions to parts of the brain, but it is 
>>pure speculation to conclude that we are purely mechanistic.

>  With the theories of Quantum Mechanics and Chaos been so successful
>of late (not that I have read enough about them), I am curious to know
>whether or not the brain is as susceptible to unpredictability as, for
>instance, the weather.  Do neurons always behave in a deterministic
>fashion, or do they exhibit random fluctuations?

   From what I have read of research on the matter, there seems to be
quite strong evidence that they behave deterministically by probabilistic
rules.  The properties of neuron firing come from the actions of a large
number of protein gates that let ions through with a certain probability
based on the presense of other proteins or magnetic fields (depending on
which type of gate we are speaking of, there are a large number of types
present).  The overall effect of all of these probabilities seem to be
a fairly deterministic firing ability, but if you want to model it that
closely, it reduces to quantum mechanical problems.

>                                                  Could a neural
>network amplify these variations in behaviour like a ball bouncing
>amongst an array of pegs, never producing the same result from the
>same initial conditions?

   Yes, there has been some work that shows very chaotic results.  The
most interesting results I have heard of are measuring certain patterns
in the human brain (sorry, I can't remember the reference, but I think
that it was on a "NOVA" program sometime in the last year or two).

>                          Just how much is known about living neural
>networks, and is it a fair assumption to say that they are purely
>mechanical in function?

   Whoa.  It seems that you are mixing "chaotic" with "random".  They are
not the same phenomena.  Chaos is fundamentally a study of deterministic
systems...  systems that appear random on the surface, but have well-defined
relationships running them.  Chaotic systems are quite mechanistic, but
they don't seem to follow our idea of 

>  I quite often wonder about the rationale behind searching for a
>deterministic model of the brain, when so much natural phenomena is
>chaotic and inherently unpredictable in nature.  Obviously there are
>some quite dramatic philosophical implications that would be raised if
>the brain were found to be governed by the laws of Chaos, but I am
>often surprised to find that the majority of people find these implications
>unsavory rather than potentially revolutionary.

   If you are speaking of the brain being inherently *random*, I agree that
it would be dramatic.  As for it being chaotic, I think that many people
already believe this.  The arguments about the random/nonrandom nature of
the underlying mechanisms in the brain rage as we speak ;-).  Some people
imply that the "random" parts need to be truly random for the brain to
work as a true intelligence, so that even the stochastic laws on top wouldn't
give rise to intelligence.

   I don't find the idea of randomness so much unsavory as counter-intuitive.
It would be quite interesting, though...  it twists my mind.  Part of the
problem might be that we cling to the macro-scale interpretation of waves,
for instance...  but that's another discussion ;-).

>  With the scientific models of the world gradually leaning towards an
>acknowledgement of the unpredictable nature of the universe, why do
>people still cling so dramatically to mechanistic models of
>consciousness?  [I think I already know some of the reasons, but I
>want to hear the views of others first].

   There is a *lot* of evidence to imply determinism, at least on the
macro-level...  and neurons appear to function on the macro-level, enless you
insist that the quantum fluxations are still present.  If they are truly
random anyway, they so nearly cancel out that it is almost not worth the
effort, and on top of that the stimulus that we give it would introduce
its own "fluxuations", so to speak, as stimulus from the real world has
irregularities in it.  There are certain arguments that I am not addressing,
but I don't think it is the function of science to give up before it tries.

   Erich

             "I haven't lost my mind; I know exactly where it is."
     / --  Erich Stefan Boleyn  -- \       --=> *Mad Genius wanna-be* <=--
    { Honorary Grad. Student (Math) }--> Internet E-mail: <erich@cs.pdx.edu>
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