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From: tsmith@gryphon.CTS.COM (Tim Smith)
Newsgroups: comp.ai
Subject: Re: The Success of AI
Message-ID: <1993@gryphon.CTS.COM>
Date: Wed, 21-Oct-87 01:30:58 EDT
Article-I.D.: gryphon.1993
Posted: Wed Oct 21 01:30:58 1987
Date-Received: Fri, 23-Oct-87 06:38:52 EDT
References: <193@PT.CS.CMU.EDU>
Reply-To: tsmith@gryphon.CTS.COM (Tim Smith)
Organization: Trailing Edge Technology, Redondo Beach, CA
Lines: 90

In article <193@PT.CS.CMU.EDU> spe@spice.cs.cmu.edu (Sean Engelson) writes:
+=====
| Given a sufficiently powerful computer, I could, in theory, simulate
| the human body and brain to any desired degree of accuracy.  This
| gedanken-experiment is the one which put the lie to the biological
| anti-functionalists, as, if I can simulate the body in a computer, the
| computer is a sufficiently powerful model of computation to model the
| mind.  I know, for example, that serial computers are inherently as
| powerful computationally as parallel computers, though not as
| efficient, as I can simulate parallel processing on essentially serial
| machines.  So we see, that if the assumption that the mind is an
| inherent property of the body is accepted, we must also accept that a
| computer can have a mind, if only by the inefficient expedient of
| simulating a body containing a mind.
|        -Sean-
+=====
My claim is, specifically, that you cannot simulate a human
being (body and mind) with a digital computer, either in theory
or practice.  Not a few people with whom I am in basic agreement
would claim that, well, it just *might* be conceivable in
theory, but you could never do it in practice.

I'ts not clear what is meant by "in theory" here. It sounds like
an unacceptable hedge. You might, for example, claim that with a
very large number of computers, all just at the edge of the
speed boundaries dictated by the laws of physics in the most
advanced materials imaginable, you could simulate a human body
and mind--but not in real time. But the simulation would have to
be in real time, because humans live in real time, doing things
that are critically time dependent (perceiving speech, for
example).

Similarly, humans think the way they do partially because of
their size, because of the environment they live in, because of
the speed at which they move, live, and think.

One of the consistent failings of AI researchers is to vastly
underestimate the intricacy and complexity of the kinds of
things they are trying to model (of course most of the other
cognitive scientists in this century have also underestimated
these things). Playing chess is nothing compared with natural
language understanding. We take language understanding for
granted, because, after all, we all do it.  Yet we consider a
chess grand master brilliant, because we cannot match his
skills. But in fact, becoming a chess grand master is not more
difficult than learning to speak and write English. It's easier.
We learn language because we start early, spend *lots* and
*lots* of time doing it, and it's fun (watch children playing
word games sometime).  We recognize that it's learn to speak or
perish, in a sense. Many fewer people are motivated (at the
early age required) to learn to play chess at the GM level.

The trouble with the kind of naive (if you'll pardon the
expression) reductionism inherent in your position is that it
seems to assume that any set of physical interactions that can
be expressed mathematically can be scaled up to a full-scale
simulation, and that this simulation would be indistinguishable
from the original thing.

Leaving aside AI for a moment, consider weather simulations.
Metereologists have developed computerized simulations of
phenomena such as hurricanes.  Based on lots of data from past
storms, they can predict, with some accuracy, how a developing
storm might behave. This is obviously an extremely useful
capability. But to claim that a computer simulation of a
hurricane is exactly the same as the real thing would probably
sound like a very poor joke to someone who has experienced a
hurricane first-hand.

It seems to me that any intelligent person would say "how could
you ever truly simulate a hurricane, and why would you want to?"
Well, I have the same reaction to those who say that they want
to simulate human intelligence, or even some essential part of
it such as natural language understanding. How, and for God's
sake, *why*?  To study human intelligence, using computers and
any other tools available, is a fascinating thing to do. I have
spent a number of years doing so. But to say that we are
approaching an era when human intelligence will be simulated
seems to be just about like saying that from the puff of air
generated by the wave of a hand it is only a few short steps to
a full-scale realistic simulation of a hurricane.

Know what it is you are trying to simulate!


-- 
Tim Smith
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