From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!psych.toronto.edu!michael Mon Mar  9 18:34:37 EST 1992
Article 4201 of comp.ai.philosophy:
Newsgroups: comp.ai.philosophy
Path: newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!psych.toronto.edu!michael
>From: michael@psych.toronto.edu (Michael Gemar)
Subject: Re: Definition of understanding
Organization: Department of Psychology, University of Toronto
References: <44140@dime.cs.umass.edu> <1992Mar2.172515.15389@psych.toronto.edu> <1992Mar2.190455.17079@mp.cs.niu.edu>
Message-ID: <1992Mar2.214012.22715@psych.toronto.edu>
Date: Mon, 2 Mar 1992 21:40:12 GMT

In article <1992Mar2.190455.17079@mp.cs.niu.edu> rickert@mp.cs.niu.edu (Neil Rickert) writes:

> It is not difficult to take a reasonably bright 10 year old, and teach him
>the manipulations of the Euclidean algorithm for computing greatest common
>divisors.  And you can do so as a purely mechanical operation.  If asked,
>he would answer that he knows nothing about greatest common divisors or
>how to compute them.  Yet clearly the system does.

Nonsense.  This "system" *understands* nothing.  It is merely a formal
syntactic system.  Just like the child, it has *nothing* in it that
refers to "greatest common divisors" and the like.

Let's take an example from physics.  You teach a child how to calculate
the potential energy of a pendulum by the formula:

PE = 1/2 k x^2

where PE = potential energy
       k = spring constant
       x = displacement from equilibrium

You do so as a purely mechanical operation.  If asked, he would answer
that he knows nothing about potential energy, or spring constants, or
the like.

You then say, "Aha, but the *system* that calculates potential energy
in a spring does!"  However, someone who knows electrostatics says,
"But wait!  That's also the formula for calculating the electrostatic 
energy *in a capacitor*.  Simply *interpret* k as C (capacitance) and
x as V (potential across the capacitor plates)."  *Now* what does the
system "understand"?  Only pendulums?  Only capacitors?  Pendulums *and*
capacitors?  I'd vote for neither, myself.

BTW, this is a good example of how interpretation can play a large role
in the attribution of "understanding" to a program.  If an electronics
engineer had a program he used to calculate the PE of a capacitor, he or she
would probably say that the program *actually did calculate electrostatic 
energy*.  But it doesn't.  It merely submits the inputs to certain syntactic
rules, and provides outputs.  The *exact same program* could be used to
calculate the potential energy in a spring system.  The program itself
does not *refer* to capacitors - it doesn't "refer" to anything.  It is
only our *interpretation* of the inputs and outputs which give meaning.

- michael




