From: choy@skorpio.usask.ca (I am a terminator.)
Subject: Re: Turing Indistinguishability is a Scientific Criterion
Organization: University of Saskatchewan, Saskatoon, Canada
Date: Tue, 8 Sep 1992 21:59:13 GMT

In article <1992Sep6.200121.4383@Princeton.EDU>, harnad@phoenix.Princeton.EDU (Stevan Harnad) writes:
|> 
|>    Harnad, S. (1992) The Turing test is not a trick: Turing
|>    indistinguishability is a scientific criterion. SIGART Bulletin 3(4)
|>    (October 1992) pp. 9 - 10. [Appears preceded by an Editorial on the
|>    Turing Test by Lewis Johnson, pp. 7 - 9, and followed by another
|>    commentary by Stuart Shapiro, p. 10]
|> ------------------------------------------------------------------------
|>                   THE TURING TEST IS NOT A TRICK:
|>       TURING INDISTINGUISHABILITY IS A SCIENTIFIC CRITERION
|> 
|>                          Stevan Harnad
|>       Department of Psychology      Cognition et Mouvement URA CNRS 1166
|>         Princeton University            Universite d'Aix Marseille II
|>          Princeton NJ 08544           13388 Marseille cedex 13, France
|> 
|> It is important to understand that the Turing Test (TT) is not, nor was
|> it intended to be, a trick; how well one can fool someone is not a
|> measure of scientific progress. The TT is an empirical criterion: It
|> sets AI's empirical goal to be to generate human-scale performance
|> capacity. This goal will be met when the candidate's performance is totally
|> indistinguishable from a human's. Until then, the TT simply represents
|> what it is that AI must endeavor eventually to accomplish scientifically.

Why should we wish for complete indistinguishability? Would you demand
that Tom's answers be exactly the same as Dick's and Harry's? I'm not
sure what Turing said, but what is an acceptable difference between the
responses of 2 humans? What kind of humans are being considered? What
is to stop the human test subject from being a computer scientist who
talks using his own AI algorithm?

What if a computer is smarter than a person? Then there is a distinction,
but the person has to "endeavor eventually to accomplish" what the
computer is doing. 

|> Pen-Pals Versus Robots
|> 
|> In my own papers I have tried to explain how trickery, deception and
|> impersonation have nothing at all to do with the scientific import of
|> Turing's criterion (Harnad 1989, 1991). AI is not a party game. The
|> game was just a metaphor. The real point of the TT is that if we had a
|> pen-pal whom we had corresponded with for a lifetime, we would never
|> need to have seen him to infer that he had a mind. So if a machine
|> pen-pal could do the same thing, it would be arbitrary to deny it had a
|> mind just because it was a machine. That's all there is to it!
|> 
|> This entirely valid methodological point of Turing's is based on the
|> "other minds" problem (the problem of how I can know that anyone else
|> but me actually has a mind, actually thinks, actually has intelligence
|> or knowledge -- these all come to the same thing): It is arbitrary to
|> ask for more from a machine than I ask from a person, just because it's
|> a machine (especially since no one knows yet what either a person or a
|> machine REALLY is). So if the pen-pal TT is enough to allow us to
|> correctly infer that a real person has a mind, then it must by the same
|> token be enough to allow us to make the same inference about a
|> computer, given that the two are totally indistinguishable to us (not
|> just for a 5-minute party trick or an annual contest, but, in
|> principle, for a lifetime). Neither the appearance of the candidate nor
|> any facts about biology play any role in my judgment about my human pen
|> pal, so there is no reason the same should not be true of my
|> TT-indistinguishable machine pen-pal.
|> 
|> Now, although I too am critical of the TT, I think it is important that
|> its logic -- which was only implicit in Turing's actual writing --
|> should be made explicit, as I have tried to make it here and in my
|> other writings, so we can see clearly the methodological basis for his
|> proposed criterion. Elsewhere I have gone on to take issue with the TT
|> on the basis of the fact that humans also happen to have a good deal
|> more performance capacity over and above their pen-pal capacity. It is hence
|> arbitrary and equivocal to focus only on pen-pal capacity; but Turing's
|> basic intuition is still correct that the only available basis for
|> inferring a mind is Turing-indistinguishable performance capacity. For
|> TOTAL performance indistinguishability, however, one needs TOTAL, not
|> partial, performance capacity, and that happens to call for all of our
|> robotic performance capacities too: The Total Turing Test (TTT). And,
|> as a bonus, the robotic capacities can be used to GROUND the pen-pal
|> (symbolic) capacities, thereby solving the "symbol grounding problem"
|> (Harnad 1990), which afflicts the pen-pal version of the TT, but not
|> the robotic TTT.**
|> 
|> --
|> ** FOOTNOTE: In a nutshell, the symbol grounding problem can be stated
|> as follows: Computers manipulate meaningless symbols that are
|> systematically INTERPRETABLE as meaning something. The problem is that
|> the interpretations are not intrinsic to the symbol manipulating
|> system; they are made by the mind of the external interpreter (as when
|> I interpret the letters from my TT pen-pal as meaningful messages).
|> This leads to an infinite regress if we try to assume that what
|> goes on in MY mind is just symbol manipulation too, because the thoughts
|> in my mind do not mean what they mean merely because they are
|> interpretable by someone ELSE's mind: Their meanings are intrinsic. One
|> possible solution would be to ground the meanings of a system's symbols
|> in the system's capacity to discriminate, identify, and manipulate
|> the objects that the symbols are interpretable as standing for (Harnad
|> 1987), in other words, to ground its symbolic capacities in its robotic
|> capacities. Grounding symbol-manipulating capacities in
|> object-manipulating capacities is not just a matter of attaching the
|> latest transducer/effector technologies to a computer, however. Hybrid
|> systems may need to make extensive use of analog components and perhaps
|> also neural nets, in order to connect symbols to their objects (Harnad et
|> al. 1991; Harnad 1992).
|> --

Is there such a thing as meaning? When a 486 gets a binary instruction to
ADD, it acts, but who can say it does not understand addition?

|> In fact, one of the reasons no computer has yet passed the TT may be that
|> even successful TT capacity has to draw upon robotic capacity. A TT
|> computer pen-pal alone could not even tell you the color of the flower
|> you had enclosed with its birthday letter -- or indeed that you had
|> enclosed a flower at all, unless you mention it in your letter. An
|> infinity of possible interactions with the real world, interactions of
|> which each of us is capable, is completely missing from the TT (and
|> again, "tricks" have nothing to do with it).

We think there is a range or spectrum of intelligence. There is a way
to measure intelligence. Can something be intelligent by being what it
is? Can a rock be intelligent in that it takes its shape and occupies its
space (i.e., it's path through the universe)? After all, nothing else
claims that same space. That rock has carved a niche for itself in the
universe. How about the subatomic particle that behaves as it does, not
as we would like it to? It has its own way, and nertz to all who think
differently. Some people wonder if a flower growing into symmetry and
beauty does mathematics. Perhaps everything in the universe follows its
own path, a path where some things come together to formulate statements
asserting the existence of intelligence in particular collections of
particles.

|> Is the Total Turing Test Total Enough?
|> 
|> Note that all talk about "percentages" in judging TT performance is
|> just numerology. Designing a machine to exhibit 100% Turing
|> indistinguishable performance capacity is an empirical goal, like
|> designing a plane with the capacity to fly. Nothing short of the TTT or
|> "total" flight, respectively, meets the goal. For once we recognize that
|> Turing-indistinguishable performance capacity is our mandate, the
|> Totality criterion comes with the territory. Subtotal "toy" efforts are
|> interesting only insofar as they contain the means to scale up to
|> life-size. A "plane" that can only fall, jump, or taxi on the ground is
|> no plane at all; and gliding is pertinent only if it can scale up to
|> autonomous flight.

There are physical limits such as the one on the bandwidth of a noisy
line, but something that passes for human on a TT. Is it at the
fundamental limit of intelligence? How much is human intelligence?
If the inventor of a supersmart machine obtains great knowledge with
the machine, s/he can publish the knowledge and be hailed as very
intelligent. We won't say that people are as intelligent as they
can be without the use of any tools such as pocket calculators, etc.
A machine running a known process may be doing that process faster
than a person, but the village idiot can do any step of the process
given the status register and the step. Is there a step that takes
more than the village idiot to do? Would this separate intelligent
beings from blockheads?

|> The Loebner Prize Competition is accordingly trivial from a scientific
|> standpoint. The scientific point is not to fool some judges, some of
|> the time, but to design a candidate that REALLY has indistinguishable
|> performance capacities (respectively, pen-pal performance [TT] or
|> pen-pal + robotic performance [TTT]); indistinguishable to any judge,
|> and for a lifetime, just as yours and mine are. No tricks! The real thing!
|> 
|> The only open questions are (1) whether there is more than one way to
|> design a candidate to pass the TTT, and if so, (2) do we then need a
|> stronger test, the TTTT (neuromolecular indistinguishability), to pick
|> out the one with the mind?

If there's more than one way, then which one has the mind? If you say
A is different than B, that does not say at least A or B has a mind.

|> My guess is that the constraints on the TTT
|> are tight enough, being roughly the same ones that guided the Blind
|> Watchmaker who designed us (evolutionary adaptations -- survival and
|> reproduction -- are largely performance matters; Darwinian selection
|> can no more read minds than we can).
|> 
|> Let me close with the suggestion that the problem under discussion is
|> not one of definition. You don't have to be able to define
|> intelligence (knowledge, understanding) in order to see that people have
|> it and today's machines don't.

I don't have to define jindon, but we can damn well see that machines have
it and people don't. Thank God.

|> Nor do you need a definition to see that
|> once you can no longer tell them apart, you will no longer have any
|> basis for denying of one what you affirm of the other.

But we don't go to the factory to build people. We must build better
things. Then we start getting a basis for something. For instance, we
don't have unisex washrooms.


Henry Choy
choy@cs.usask.ca
Newsgroups: comp.ai