Turing machines = connectionist models

[AMR@ibm.com]

My point was to claim that biological systems are indistinguishable
from robots.  Rather it is that a variety of recent proposals about
how they are distinguished do not make the grade.  In particular,
grounding as I understand Harnad's proposal is not even intended to
make the distinction.  I think he contends that robots are just
as grounded as people are, but that disembodied (non-robotic) programs
are not.  I think the distinction between robots and programs is
very great in practice but not all in principle (as I tried to elucidate)
and I should make it clear if I have not yet that I don't think that
existing or currently imaginable robots are any closer to being human-like
than are existing or currently imaginable programs.  So, for me, the
crucial question is precisely what makes people different from baboons,
or robots, or programs.  And grounding does not help us answer this.

The question of how biological systems differ from nonbiological is
equally interesting, but that has to do with the fundamental problem
of WHAT IS LIFE not (or at least not obviously) with the fundamental
problem of WHAT IS INTELLIGENCE.  The claim that somehow people have
minds but robots and programs do not BECAUSE people are biological
in nature (a claim that Searle seems close to making) seems prima
facie unlikely, since we do not attribute minds to cells or to amoebas,
which are biological entities, and in any case the claim has not been
either articulated precisely or defended even in outline.

Additional proposals have been made, having to do with intentionality
or semantics, for example, but these again do not seem to help.  They
are either vague or they do not distinguish people from robots or
perhaps do no more than recapitulate the problem without throwing
any new light on it.

I should finally say that when I urge the study of the theory of com
putation on people, I do not mean to disparage other branches of
mathematics.  If there are other branches of mathematics that are
equally or more useful here, I would like to know more about them.
I would just say that (a) such results are ultimately going to have
to be put together with what we already have in the theory of computation,
to the undoubted benefit of the latter, (b) such results should, if
they are to be helpful, make the distinctions I have been referring to
(and I would like to see an example of this), (c) such results will
I think be equally unconfortable for the handwavers as the classic
results from the theory of computation precisely because they will tell
us in precise and mathematical terms what kind of machine (different in
some important way from other kinds of machine) people actually are, and
(d) (referring back to (b) such results are unlikely, it seems to me,
to show either that only a biological system could be intelligent or
that only a net of some kind could.

The question of whether connectionist models are equivalent (in various
senses) to finite-state machines, then, is not intended to be the
central question. Most of the questions are actually empirical,
but the fact remains that we need a precise framework for carrying onn
the empirical and theoretical work, and, in any case, we cannot hope
for useful results from work which starts out by flouting the few
truths that we do know for sure from the mathematics of the theory
of computation.