harnad@mind.UUCP (02/19/87)
"CUGINI, JOHN" <cugini@icst-ecf> wrote on mod.ai: > The Big Question: Is your brain more similar to mine than either > is to any plausible silicon-based device? That's not the big question, at least not mine. Mine is "How does the mind work?" To answer that, you need a functional theory of how the mind works, you need a way of testing whether the theory works, and you need a way of deciding whether a device implemented according to the theory has a mind. That's what I proposed the formal and informal TTT for: testing and implementing a functional theory of mind. Cugini keeps focusing on the usefulness of "presence of `brain'" as evidence for the possession of a mind. But in the absence of a functional theory of the brain, its superficial appearance hardly helps in constructing and testing a functional theory of the mind. Another way of putting it is that I'm concerned with a specific scientific (bioengineering) problem, not an exobiological one ("Does this alien have a mind?"), nor a sci-fi one ("Does this fictitious robot have a mind?"), nor a clinical one ("Does this comatose patient or anencephalic have a mind?"), nor even the informal, daily folk-psychological one ("Does this thing I'm interacting with have a mind?"). I'm only concerned with functional theories about how the mind works. > A member of an Amazon tribe could find out, truly know, that light > switches cause lights to come on, with a few minutes of > experimentation. It is no objection to his knowledge to say that he > has no causal theory within which to embed this knowledge, or to > question his knowledge of the relevance of the similarities among > various light switches, even if he is hard-pressed to say anything > beyond "they look alike." Again, I'm not concerned with informal, practical, folk heuristics but with functional, scientific theory. > Now, S. Harnad, upon your solemn oath, do you have any serious > practical doubt, that, in fact, > 1. you have a brain? > 2. that it is the primary cause of your consciousness? > 3. that other people have brains? > 4. that these brains are similar to your own My question is not a "practical" one, but a functional, scientific one, and none of these correlations among superficial appearances help. > how do you know that two performances > by two entities in question (a human and a robot) are relevantly > similar? What is it precisely about the performances you intend to > measure? How do you know that these are the important aspects? > ...as I recall, the TTT was a kind > of gestalt you'll-know-intelligent-behavior-when-you-see-it test. > How is this different from looking at two brains and saying, yeah > they look like the same kind of thing to me? Making a brain look-alike is a trivial task (they do it in Hollywood all the time). Making a (TTT-strength) behavioral look-alike is not. My claim is that a successful construction of the latter is as close as we can hope to get to a functional understanding of the mind. There's no "measurement" problem. The data are in. Build a robot that can detect, discriminate, identify, manipulate and describe objects and events and can interact linguistically indistinguishably from the way we do (as ultimately tested informally by laymen) and you'll have the problem licked. As to "relevant" similarities: Perhaps the TTT is too exacting. TOTAL human performance capacity may be more than what's necessary to capture mind (for example, nonhuman species and retarded humans also have minds). Let's say it's to play it safe; to make sure we haven't left anything relevant out; in any case, there will no doubt be many subtotal way-stations on the long road to the asymptotic TTT. The brain's another matter, though. Its structural appearance is certainly not good enough to go on. And its function is an ambiguous matter. On the one hand, its behavioral capacities are among its functional capacities, so behavioral function is a subset of brain function. But, over and above that we do not know what implementational details are relevant. The TTT could in principle be beefed up to demand not only behavioral indistinguishability, but anatomical, physiological and pharmacologcal indistinguishability. I'd go for the behavioral asymptote first though, as the most likely criterion of relevance, before adding on implementational constraints too -- especially because those implementational details will play no role in our intuitive judgments about whether the device in question has a mind like us, any more than they do now. Nor will they significantly increase the objective validity of the (frail) TTT criterion itself, since brain correlates are ultimately validated against behavioral correlates. My own guess, though, is that our total performance capacity will be as strong a hardware constraint as is needed to capture all the relevant functional similarities. > Just a quick pout here - last December I posted a somewhat detailed > defense of the "brain-as-criterion" position... > No one has responded directly to this posting. I didn't reply because, as I indicated above, you're not addressing the same question I am (and because our exchanges have become somewhat repetitive). -- Stevan Harnad (609) - 921 7771 {allegra, bellcore, seismo, rutgers, packard} !princeton!mind!harnad harnad%mind@princeton.csnet