Page 38 - Foundations of Cognitive Psychology : Core Readings

36 Daniel C. Dennett

truth), and the man wins if the judge makes the wrong identification. A little
reflection will convince you, I am sure, that, aside from lucky breaks, it would
take a clever man to convince the judge that he was a woman—assuming the
judge is clever too, of course.
Now suppose, Turing said, we replace the man or woman with a computer,
and give the judge the task of determining which is the human being and
which is the computer. Turing proposed that any computer that can regularly
or often fool a discerning judge in this game would be intelligent—would
be a computer that thinks—beyond any reasonable doubt. Now, it is important
to realize that failing this test is not supposed to be a sign of lack of intelli-
gence. Many intelligent people, after all, might not be willing or able to play
the imitation game, and we should allow computers the same opportunity to
decline to prove themselves. This is, then, a one-way test; failing it proves
nothing.
Furthermore, Turing was not committing himself to the view (although it is
easy to see how one might think he was) that to think is to think just like a hu-
man being—any more than he was committing himself to the view that for a
man to think, he must think exactly like a woman. Men and women, and com-
puters, may all have different ways of thinking. But surely, he thought, if one
can think in one’s own peculiar style well enough to imitate a thinking man or
woman, one can think well, indeed. This imagined exercise has come to be
known as the Turing test.
It is a sad irony that Turing’s proposal has had exactly the opposite effect
on the discussion of that which he intended. Turing didn’t design the test as a
useful tool in scientific psychology, a method of confirming or disconfirming
scientific theories or evaluating particular models of mental function; he de-
signed it to be nothing more than a philosophical conversation-stopper. He
proposed—in the spirit of ‘‘Put up or shut up!’’—a simple test for thinking that
was surely strong enough to satisfy the sternest skeptic (or so he thought).
He was saying, in effect, ‘‘Instead of arguing interminably about the ultimate
nature and essence of thinking, why don’t we all agree that whatever that
nature is, anything that could pass this test would surely have it; then we could
turn to asking how or whether some machine could be designed and built
that might pass the test fair and square.’’ Alas, philosophers—amateur and
professional—have instead taken Turing’s proposal as the pretext for just the
sort of definitional haggling and interminable arguing about imaginary coun-
terexamples he was hoping to squelch.
This thirty-year preoccupation with the Turing test has been all the more re-
grettable because it has focused attention on the wrong issues. There are real
world problems that are revealed by considering the strengths and weaknesses
of the Turing test, but these have been concealed behind a smokescreen of
misguided criticisms. A failure to think imaginatively about the test actually
proposed by Turing has led many to underestimate its severity and to confuse
it with much less interesting proposals.
So first I want to show that the Turing test, conceived as he conceived it, is
(as he thought) plenty strong enough as a test of thinking. I defy anyone to
improve upon it. But here is the point almost universally overlooked by the
literature:There is a common misapplication of the sort of testing exhibited by