bwk@mbunix.mitre.org (Barry W. Kort) (03/05/89)
The Turtling Test
Barry Kort
(With apologies to Douglas Hofstadter)
Achilles: Good morning, Mr. T!
Tortoise: Good day, Achilles. What a wonderful day for
touring the computer museum.
Achilles: Yes, it's quite amazing to realize how far our
computer technology has come since the days of Von
Neumann and Turing.
Tortoise: It's interesting that you mention Alan Turing, for
I've been doing some biographical research on him.
He is a most interesting and enigmatic character.
Achilles: Biographical research? That's a switch. Usually
people like to talk about his Turing Test, in
which a human judge tries to distinguish which of
two individuals is the human and which is the
computer, based on their answers to questions
posed by the judge over a teletype link. To tell
you the truth, I'm getting a little tired of
hearing people talk about it so much.
Tortoise: You have a fine memory, my friend, but I'm afraid
you'll be disappointed when I tell you that the
Turing Test does come up in my work.
Achilles: In that case, don't tell me.
Tortoise: Fair enough. Perhaps you would be interested to
know what Alan Turing would have done next if he
hadn't died so tragically in his prime.
Achilles: That's an interesting idea, but of course it's
impossible to say.
Tortoise: If you mean we'll never know for sure, I would
certainly agree. But I have just come up with a
way to answer the question anyway.
Achilles: Really?
Tortoise: Really. You see, I have just constructed a model
of Alan Turing's brain, based on a careful
examination of everything he read, saw, did, or
wrote about during his tragic career.
Achilles: Everything?
Tortoise: Well, not quite everything. Just the things I
know about from the archives and from his notes
and effects. That's why it's just a model and not
an exact duplicate of his brain. It would be a
perfect model if I could discover everything he
ever saw, learned, or discovered.
Achilles: Amazing!
Tortoise: Since Turing had a very logical mind, I merely
start with his accumulated knowledge and reason
logically to what he would have investigated next.
Interestingly, this leads to a possible hypothesis
explaining why Turing committed suicide.
Achilles: Fantastic! Let's hear your theory.
Tortoise: A logical next step after devising the Turing Test
would be to give the formal definition of a Turing
Machine to computer `A' (which, since it's a
computer, happens to be a Turing Machine itself)
and ask it to decide if another system (call it
machine `B') is a Turing Machine.
Achilles: I don't get it. What is machine `A' supposed to
do to decide the question?
Tortoise: Why it merely devises a test which only a Turing
Machine could pass, such as a computation that a
lesser beast would choke on. Then it administers
the Test to machine `B' to see how it handles the
challenge.
Achilles: Are you sure that a Turing Machine knows how to
devise such a test in the first place?
Tortoise: That's a good question. I suppose it depends on
how the definition of a Turing Machine is stated.
Clearly, a good definition would be one which
states or implies a practical way to decide if an
arbitrary hunk of matter possesses the property of
being a Turing Machine. In this case, it's safe
to assume that the problem was well-posed, meaning
that the definition was sufficiently complete.
Achilles: So what happened next?
Tortoise: You mean what does my model of Turing's brain
suggest as the next logical step?
Achilles: Of course, Mr. T. I quite forgot what level we
were operating on.
Tortoise: Next, Machine `A' would be asked if Machine `A'
itself fit the definition of a Turing Machine!
Achilles: Wow! You mean you can ask a machine to examine
its own makeup?
Tortoise: Why not? In fact many modern computers have
built-in self diagnostic systems. Why can't a
computer devise a diagnostic program to see what
kind of computer it is? As long as it's given the
definition of a Turing Machine, it can administer
the test to itself and see if it passes.
Achilles: Holy Holism! Computers can become self-aware of
what they are?!
Tortoise: That would seem to be the case.
Achilles: What happens next?
Tortoise: You tell me.
Achilles: The Turing Machine tries the Turing Test on a
human.
Tortoise: Very good. And what is the outcome?
Achilles: The human passes?
Tortoise: Right!
Achilles: So Alan Turing concludes that he's nothing more
than a Turing Machine, which makes him so
depressed he eventually commits suicide.
Tortoise: Maybe.
Achilles: What else could there be?
Tortoise: Let's go back to your last conclusion. You said,
"Turing concludes that he's nothing more than a
Turing Machine."
Achilles: I don't follow your point.
Tortoise: Suppose Turing wants to prove conclusively that he
was something more than "just a Turing Machine."
Achilles: I see. He had a Turing Machine in him, but he
wanted to know what else he was that was more than
just a machine.
Tortoise: Right. So he searched for some way to discover
how he differed from a machine in an important
way.
Achilles: And he couldn't discover any way?
Tortoise: Not necessarily. He may have known of several
ways. For example, he could have tried to fall in
love.
Achilles: Why falling in love is the easiest thing in the
world.
Tortoise: Not if you try to do it. Then it's impossible!
Achilles: I see your point.
Tortoise: In any event, there is no evidence that Turing
ever fell in love, even though he must have known
it was possible. Maybe he didn't know that one
shouldn't try so hard.
Achilles: So he committed suicide in despair?
Tortoise: Maybe.
Achilles: What else could there be?
Tortoise: The last possibility that comes to mind is that
Turing suspected there was something he was
overlooking.
Achilles: And what is that?
Tortoise: Could a Turing Machine discover the properties of
a Turing Machine without being told?
Achilles: Gee, I don't know. But it could discover the
properties of another machine that it could do
experiments on.
Tortoise: Would it ever think to do such experiments on
itself?
Achilles: I don't know. Does it even know what the word
"itself" points to?
Tortoise: Who would have given it the idea of "self"?
Achilles: I don't know. It reminds me of Narcissus
discovering his reflection in a pool of water and
falling in love with himself.
Tortoise: Well, I haven't finished my research yet, but I
suspect that a Turing Machine, without outside
assistance, could not discover the complete
definition of itself, nor would it think to ask
itself the question, "Am I a Turing Machine?" if
it were simply given the definition of one as a
mathematical abstraction.
Achilles: In other words, if Alan Turing did ask himself the
question, "Am I (Alan Turing) a Turing Machine?"
the very act of posing the question proves he
isn't one!
Tortoise: That's my conjecture.
Achilles: So he committed suicide to prove he wasn't one,
because he didn't realize that he already had all
the evidence he needed to prove that he was
intellectually more complex than a mere Turing
Machine.
Tortoise: Perhaps.
Achilles: Well, I would be most interested to discover the
final answer when you complete your research on
this most interesting question.
Tortoise: My friend, if we live long enough, we're bound to
find the answer.
Achilles: Good day, Mr. T!
Tortoise: Good day, Achilles.