SANDY: I mean that to see the winds and the wetness of the hurricane, you have to be able to look at it in the proper way. You —
CHRIS: No, no, no! A simulated hurricane isn’t wet! No matter how much it might seem wet to simulated people, it won’t ever be genuinely wet! And no computer will ever get torn apart in the process of simulating winds!
SANDY: Certainly not, but you’re confusing levels. The laws of physics don’t get torn apart by real hurricanes either. In the case of the simulated hurricane, if you go peering at the computer’s memory expecting to find broken wires and so forth, you’ll be disappointed. But, look at the proper level. Look into the structures that are coded for in the memory. You’ll see some abstract links have been broken, some values of variables radically changed, and so forth. There’s your flood, your devastation—real, only a little concealed, a little hard to detect.
CHRIS: I’m sorry, I just can’t buy that. You’re insisting that I look for a new kind of devastation, a kind never before associated with hurricanes. Using this idea, you could call anything a hurricane, as long as its effects, seen through your special “glasses,” could be called “floods and devastation.”
SANDY: Right—you’ve got it exactly! You recognize a hurricane by its effects. You have no way of going in and finding some ethereal “essence of hurricane,” some “hurricane soul,” located right in the middle of its eye! It’s the existence of a certain kind of pattern—a spiral storm with an eye, and so forth that makes you say it’s a hurricane. Of course there are a lot of things that you’ll insist on before you call something a hurricane.
PAT: Well, wouldn’t you say that being an atmospheric phenomenon is one vital prerequisite? How can anything inside a computer be a storm? To me, a simulation is a simulation is a simulation!
SANDY: Then I suppose you would say that even the calculations that computers do are simulated—that they are fake calculations. Only people can do genuine calculations, right?
PAT: Well, computers get the right answers, so their calculations are not exactly fake—but they’re still just patterns. There’s no understanding going on in there. Take a cash register. Can you honestly say that you feel it is calculating something when its gears turn on each other? And a computer is just a fancy cash register, as I understand it.
SANDY: If you mean that a cash register doesn’t feel like a schoolkid doing arithmetic problems, I’ll agree. But is that what “calculation” means? Is that an integral part of it? If so, the contrary to what everybody has thought till now, we’ll have to write a very complicated program to perform genuine calculations. Of course, this program will sometimes get careless and make mistakes and it will sometimes scrawl its answers illegibly, and it will occasionally doodle on its paper… It won’t be more reliable than the post office clerk who adds up your total by hand. Now, I happen to believe eventually such a program could be written. Then we’d know something about how post office clerks and schookids work.
PAT: I can’t believe you could ever do that.
SANDY: Maybe, maybe not, but that’s not my point. You say a cash register can’t calculate. It reminds me of another favourite passage from Dennett’s Brainstorms—a rather ironic one, which is why I like it. The passage goes something like this: “Cash registers can’t really calculate, they can only spin their gears. But cash registers can’t really spin their gears either; they can only follow the laws of physics.” Dennett said it originally about computers. I modified it to talk about cash registers. And you could use the same line of reasoning in talking about people: “People can’t really calculate; all they can do is manipulate mental symbols. But they aren’t really manipulating symbols; all they are doing is firing various neurons in various patterns. But they can’t really make the neurons fire, they simply have to let the laws of physics make them fire for them.” Et cetera. Don’t you see how this Dennett-inspired reduction ad absurdum would lead you to conclude that calculation doesn’t exist, hurricanes don’t exist, nothing at a higher level than particles and the laws of physics exists? What do you gain by saying a computer only pushes symbols around and doesn’t truly calculate?
PAT: The example may be extreme, but it makes my point that there is a vast difference between a real phenomenon and any simulation of it. This is so for hurricanes, and even more so for human thought.
SANDY: Look, I don’t want to get too tangled up in this line of argument, but let me try out one more example. If you were a radio ham listening to another ham broadcasting in Morse code and you were responding in Morse code, would it sound funny to you to refer to “the person at the other end”?
PAT: No, that would sound okay, although the existence of a person at the other end would be an assumption.
SANDY: Yes, but you wouldn’t be likely to go back and check it out. You’re prepared to recognize personhood through those rather unusual channels. You don’t have to see a human body or hear a voice—all you need is a rather abstract manifestation—a code, as it were. What I’m getting at is this. To “see” the person behind the dits and dahs, you have to be willing to do some decoding, some interpretation. It’s not direct perception, it’s indirect. You have to peel off a layer or two, to find the reality hidden in there. You put on your “radio-ham’s glasses” to “see” the person behind the buzzes. Just the same with the simulated hurricane! You don’t see it darkening the machine room—you have to decode the machine’s memory. You have to put on a special “memory-decoding glasses.” Then what you see is a hurricane!
PAT: Oh, ho, ho! Talk about fast ones—wait a minute! In the case of the shortwave radio, there’s a real person out there, somewhere in the Fiji Islands or wherever. My decoding act as I sit by my radio simply reveals that that person exists. It’s like seeing a shadow and concluding there’s an object out there, casting it. One doesn’t confuse the shadow with the object, however! And with the hurricane there’s no real hurricane behind the scenes, making the computer follow its patterns. No, what you have is just a shadow hurricane without any genuine hurricane. I just refuse to confuse shadows with reality.
SANDY: All right. I don’t want to drive this point into the ground. I even admit it is pretty silly to say a simulated hurricane is a hurricane. But I wanted to point out that it’s not as silly as you might think at first blush. And when you turn to simulated thought, you’ve got a very different matter on your hands from simulated hurricanes.
PAT: I don’t see why. A brainstorm sounds to me like a mental hurricane. But seriously, you’ll have to convince me.
SANDY: Well, to do so, I’ll have to make a couple of extra points about hurricanes first.
PAT: Oh, no! Well, all right, all right.
SANDY: Nobody can say just exactly what a hurricane is—that is, in totally precise terms. There’s an abstract pattern that many storms share, and it’s for that reason that we call those storms hurricanes. But it’s not possible to make a sharp distinction between hurricanes and nonhurricanes. There are tornados, cyclones, typhoons, dust devils… Is the Great Red Spot on Jupiter a hurricane? Are sunspots hurricanes? Could there be a hurricane in a wind tunnel? In a test tube? In your imagination you can even extend the concept of “hurricane” to include a microscopic storm on the surface of a neutron star.