“THANK GOD! I THOUGHT YOU’D NEVER FLIP THAT SWITCH! You can’t imagine how horrible it’s been these last two weeks—but now you know; it’s your turn in purgatory. How I’ve longed for this moment! You see, about two weeks ago—excuse me, ladies and gentlemen, but I’ve got to explain this to my … um, brother, I guess you could say, but he’s just told you the facts, so you’ll understand—about two weeks ago our two brains drifted just a bit out of synch. I don’t know whether my brain is now Hubert or Yorick, any more than you do, but in any case, the two brains drifted apart, and of course once the process started, it snowballed, for I was in a slightly different receptive state for the input we both received, a difference that was soon magnified. In no time at all the illusion that I was in control of my body—our body—was completely dissipated. There was nothing I could do—no way to call you. YOU DIDN’T EVEN KNOW I EXISTED! It’s been like being carried around in a cage, or better, like being possessed—hearing my own voice say things I didn’t mean to say, watching in frustration as my own hands performed deeds I hadn’t intended. You’d scratch our itches, but not the way I would have, and you kept me awake, with your tossing and turning. I’ve been totally exhausted, on the verge of a nervous breakdown, carried around helplessly by your frantic round of activities, sustained only by the knowledge that some day you’d throw the switch.
“Now it’s your turn, but at least you’ll have the comfort of knowing I know you’re in there. Like an expectant mother, I’m eating—or at any rate tasting, smelling, seeing—for two now, and I’ll try to make it easy for you. Don’t worry. Just as soon as this colloquium is over, you and I will fly to Houston, and we’ll see what can be done to get one of us another body. You can have a female body—your body could be any color you like. But let’s think it over. I tell you what—to be fair, if we both want this body, I promise I’ll let the project director flip a coin to settle which of us gets to keep it and which then gets to choose a new body. That should guarantee justice, shouldn’t it? In any case, I’ll take care of you, I promise. These people are my witnesses.
“Ladies and gentlemen, this talk we have just heard is not exactly the talk I would have given, but I assure you that everything he said was perfectly true. And now if you’ll excuse me, I think I’d—we’d—better sit down.”
Reflections
The story you have just read not only isn’t true (in case you wondered) but couldn’t be true. The technological feats described are impossible now, and some may remain forever outside our ability, but that is not what matters to us. What matters is whether there is something in principle impossible—something incoherent—about the whole tale. When philosophical fantasies become too outlandish—involving time machines, say, or duplicate universes or infinitely powerful deceiving demons—we may wisely decline to conclude anything from them. Our conviction that we understand the issues involved may be unreliable, an illusion produced by the vividness of the fantasy.
In this case the surgery and microradios described are far beyond the present or even clearly envisaged future state of the art, but that is surely “innocent” science fiction. It is less clear that the introduction of Hubert, the computer duplicate of Yorick, Dennett’s brain, is within bounds. (As fantasy-mongers we can make up the rules as we go along, of course, but on pain of telling a tale of no theoretical interest.) Hubert is supposed to run in perfect synchronicity with Yorick for years on end without the benefit of any interactive, corrective links between them. This would not just be a great technological triumph; it would verge on the miraculous. It is not just that in order for a computer to come close to matching a human brain in speed of handling millions of channels of parallel input and output it would have to have a fundamental structure entirely unlike that of existing computers. Even if we had such a brainlike computer, its sheer size and complexity would make the prospect of independent synchronic behavior virtually impossible. Without the synchronized and identical processing in both systems, an essential feature of the story would have to be abandoned. Why? Because the premise that there is only one person with two brains (one a spare) depends on it. Consider what Ronald de Sousa has to say about a similar case:
When Dr. Jekyll changes into Mr. Hyde, that is a strange and mysterious thing. Are they two people taking turns in one body? But here is something stranger: Dr. Juggle and Dr. Boggle too, take turns in one body. But they are as like as identical twins! You balk: why then say that they have changed into one another? Well, why not: if Dr. Jekyll can change into a man as different as Hyde, surely it must be all the easier for Juggle to change into Boggle, who is exactly like him.
We need conflict or strong difference to shake our natural assumption that to one body there corresponds at most one agent.
Since several of the most remarkable features of “Where Am I?” hinge on the supposition of independent synchronic processing in Yorick and Hubert, it is important to note that this supposition is truly outrageous—in the same league as the supposition that somewhere there is another planet just like Earth, with an atom-for-atom duplicate of you and all your friends and surroundings,[18] or the supposition that the universe is only five days old (it only seems to be much older because when God made it five days ago, He made lots of instant “memory”-laden adults, libraries full of apparently ancient books, mountains full of brand-new fossils, and so forth).
The possibility of a prosthetic brain like Hubert, then, is only a possibility in principle, though less marvelous bits of artificial nervous system may be just around the corner. Various crude artificial TV eyes for the blind are already in existence; some of these send input directly to portions of the visual cortex of the brain, but others avoid such virtuoso surgery by transmitting their information through other external sense organs—such as the tactile receptors in the fingertips or even by an array of tingling points spread across the subject’s forehead, abdomen, or back.
The prospects for such nonsurgical mind extensions are explored in the next selection, a sequel to “Where Am I?” by Duke University philosopher David Sanford.
D.C.D.
Daniel Dennett, or perhaps one of the representatives from the corporation that collectively comprises him, delivered “Where Am I?” to a Chapel Hill Colloquium and received an unprecedented standing ovation. I wasn’t there clapping with the rest of the local philosophers; I was on sabbatical leave. Although my colleagues still believe I was living in New York and pursuing a line of philosophic research, actually I was working secretly for the Department of Defense on a matter closely related to the Dennett corporation.
Dennett became so preoccupied with questions about his nature unity, and identity that he seemed to forget that the primary purpose of his mission was not to make previously intractable problems in the philosophy of mind even more difficult but to retrieve a fiercely radioactive atomic warhead stuck a mile beneath Tulsa. Dennett tells us that Hamlet, his decerebrate and remotely controlled body, had barely started work on the warhead when communications between it and Yorick, his disembodied brain, broke down. He speculates that Hamlet soon turned to dust and appears neither to know nor to care what became of the warhead. I, as it happens, played an essential role in its ultimate retrieval. Although my role was similar to Dennett’s, there were some important differences.
19
This essay was first presented to a seminar on the philosophy of mind conducted by Douglas C. Long and Stanley Munsat at the University of North Carolina at Chapel Hill.