CHRIS: That’s not so far fetched, you know. The concept of “earthquake” has actually been extended to neutron stars. The astrophysicists say that the tiny changes in rate that once in a while are observed in the pulsing of a pulsar are caused by “glitches”—starquakes—that have just occurred on the neutron star’s surface.
SANDY: Yes, I remember that now. The idea of a “glitch” strikes me as wonderfully eerie—a surrealistic kind of quivering on a surrealistic kind of surface.
CHRIS: Can you imagine—plate tectonics on a giant rotating sphere of pure nuclear matter?
SANDY: That’s a wild thought. So starquakes and earthquakes can both be subsumed into a new, more abstract category. And that’s how science constantly extends familiar concepts, taking them further and further from familiar experience and yet keeping some essence constant. The number system is the classic example—from positive numbers to negative numbers, then rationals, reals, complex numbers, and “on beyond zebra,” as Dr. Seuss says.
PAT: I think I can see your point here, Sandy. We have many examples in biology of close relationships that are established in rather abstract ways. Often the decision about what family some species belongs to comes down an abstract pattern shared at some level. When you have your system of classification on very abstract patterns, I suppose that a broad variety of phenomena can fall into “the same class,” even if in many superficial ways the class members are utterly unlike each other. So perhaps I can glimpse, at least a little, how to you a simulated hurricane could, in some funny sense, be a hurricane.
CHRIS: Perhaps the word that’s being extended is not “hurricane” but “be”!
PAT: How so?
CHRIS: If Turing can extend the verb “think” can’t I extend the verb “be”? All I mean is that when simulated things are deliberately confused with the genuine article, somebody’s doing a lot of philosophical wool-pulling. It’s a lot more serious than just extending a few nouns such as “hurricane.”
SANDY: I like your idea that “be” is being extended, but I think your slur about “wool-pulling” goes too far. Anyway, if you don’t object, let me say just one more thing about simulated hurricanes and then I’ll get to simulated minds. Suppose you consider a really deep simulation of a hurricane—I mean a simulation of every atom, which I admit is impossibly deep. I hope you would agree that it would then share all that abstract structure that defines the “essence of hurricanehood.” So what’s to hold you back from calling it a hurricane?
PAT: I thought you were backing off from that claim of equality?
SANDY: So did I, but then these examples came up, and I was forced to go back to my claim. But let me back off, as I said I would do, and get back to thought, which is the real issue here. Thought, even more than hurricanes, is an abstract structure, a way of describing some complex events that happen in a medium called a brain. But actually thought can take place in any of several billion brains. There are all these physically very different brains, and yet they all support “the same thing”—thinking. What’s important, then, is the abstract pattern, not the medium. The same kind of swirling can happen inside any of them, so no person can claim to think more “genuinely” than any other. Now, if we come up with some new kind of medium in which the same style of swirling takes place, could you deny that thinking is taking place in it?
PAT: Probably not, but you have just shifted the question. The question now is, how can you determine whether “the same style” of swirling is really happening?
SANDY: The beauty of the Turing test is that it tells you when.
CHRIS: I don’t see that at all. How would you know that the same style of activity was occurring inside a computer as inside my minds, simply because it answered questions as I do? All you’re looking at is its outside.
SANDY: But how do you know that when I speak to you, anything similar to what you call “thinking” is going on inside me? The Turing test is a fantastic probe, something like a particle accelerator in physics. Chris, I think you’ll like this analogy. Just as in physics, when you want to understand what is going on at an atomic or subatomic level, since you can’t see it directly, you scatter accelerated particles off the target in question and observe their behaviour. From this you infer the internal nature of the target. The Turing test extends this idea to the mind. It treats the mind as a “target” that is not directly visible but whose structure can be deduced more abstractly. By “scattering” questions off a target mind, you learn something about its internal workings, just as in physics.
CHRIS: More exactly put, you can hypothesize about what kinds of internal structures might account for the behaviour observed—but they may or may not in fact exist.
SANDY: Hold on, now! Are you saying that atomic nuclei are merely hypothetical entities? After all, their existence—or should I say “hypothetical existence”?—was proven, or should I say “suggested”?—by the behaviour of particles scattered off atoms.
CHRIS: Physical systems seem to me to be much simpler than the mind, and the certainty of the inferences made is correspondingly greater.
SANDY: The experiments are also correspondingly harder to perform and to interpret. In the Turing test, you could perform many highly delicate experiments in the course of an hour. I maintain that people give other people credit for being conscious simply because of their continual external monitoring of them—which is itself something like a Turing test.
PAT: That may be roughly true, but it involves more than just conversing with people through a teletype. We see that other people have bodies, we watch their faces and expressions—we see they are fellow human beings and so we think they think.
SANDY: To me, that seems like a highly anthropocentric view of what thought is. Does that mean you would sooner say a mannikin in a store thinks than a wonderfully programmed computer, simply because the mannikin looks more human?
PAT: Obviously I would need more than just vague physical resemblances to the human form to be willing to attribute the power of thought to an entity. But that organic quality, the sameness of origin, undeniably leads a degree of credibility that is very important.
SANDY: Here we disagree. I find this simply too chauvinistic. I feel that the key thing is a similarity of internal structure—not bodily, organic, chemical structure, but organizational structure—software. Whether an entity can think seems to me to be a question of whether its organization can be described in a certain way, and I’m perfectly willing to believe that the Turing test detects the presence or absence of that mode of organization. I would say that your depending on my physical body as evidence that I am a thinking being is rather shallow. The way I see it, the Turing test looks far deeper than at mere external form.
PAT: Hey now—you’re not giving me much credit. It’s not just the shape of a body that lends weight to the idea that there’s real thinking going on inside—it’s also, as I said, the idea of common origin. It’s the idea that you and I both sprang from DNA molecules, an idea to which I attribute much depth. Put it this way: The external form of human bodies reveals that they share a deep biological history, and that it’s that depth that lends a lot of credibility to the notion that the owner of such a body can think.