Page 106 - Foundations of Cognitive Psychology : Core Readings

Minds, Brains, and Programs 107

properties that particular realizations of the formal model have, are irrelevant
to the formal model because we can always put the same formal model in
a different realization where those causal properties are obviously absent. Even
if, by some miracle, Chinese speakers exactly realize Schank’s program, we can
put the same program in English speakers, water pipes, or computers, none of
which understand Chinese, the program notwithstanding.
What matters about brain operations is not the formal shadow cast by the
sequence of synapses but rather the actual properties of the sequences. All the
arguments for the strong version of artificial intelligence that I have seen insist
on drawing an outline around the shadows cast by cognition and then claiming
that the shadows are the real thing.
By way of concluding I want to try to state some of the general philosophical
points implicit in the argument. For clarity I will try to do it in a question and
answer fashion, and I begin with that old chestnut of a question:
‘‘Could a machine think?’’
The answer is, obviously, yes. We are precisely such machines.
‘‘Yes, but could an artifact, a man-made machine, think?’’
Assuming it is possible to produce artificially a machine with a nervous sys-
tem, neurons with axons and dendrites, and all the rest of it, sufficiently like
ours, again the answer to the question seems to be obviously, yes. If you can
exactly duplicate the causes, you could duplicate the effects. And indeed it
might be possible to produce consciousness, intentionality, and all the rest of it
using some other sorts of chemical principles than those that human beings use.
It is, as I said, an empirical question.
‘‘OK, but could a digital computer think?’’
If by ‘‘digital computer’’ we mean anything at all that has a level of descrip-
tion where it can correctly be described as the instantiation of a computer pro-
gram, then again the answer is, of course, yes, since we are the instantiations of
any number of computer programs, and we can think.
‘‘But could something think, understand, and so on solely in virtue of being a
computer with the right sort of program?Could instantiating a program, the
right program of course, by itself be a sufficient condition of understanding?’’
This I think is the right question to ask, though it is usually confused with
oneormoreofthe earlierquestions,and theanswertoitisno.
‘‘Why not?’’
Because the formal symbol manipulations by themselves don’t have any
intentionality; they are quite meaningless; they aren’t even symbol manipu-
lations, since the symbols don’t symbolize anything. In the linguistic jargon,
they have only a syntax but no semantics. Such intentionality as computers
appear to have is solely in the minds of those who program them and those
who use them, those who send in the input and those who interpret the output.
The aim of the Chinese room example was to try to show this by showing
that as soon as we put something into the system that really does have inten-
tionality (a man), and we program him with the formal program, you can see
that the formal program carries no additional intentionality. It adds nothing,
for example, to a man’s ability to understand Chinese.
Precisely that feature of AI that seemed so appealing—the distinction between
the program and the realization—proves fatal to the claim that simulation could