However, in a broader sense, I decided that the question was simply misguided. So long as the jewel and the human brain shared the same sensory input, and so long as the teacher kept their thoughts in perfect step, there was only one person, one identity, one consciousness. This one person merely happened to have the (highly desirable) property that if either the jewel or the human brain were to be destroyed, he or she would survive unimpaired. People had always had two lungs and two kidneys, and for almost a century, many had lived with two hearts. This was the same: a matter of redundancy, a matter of robustness, no more.
That was the year that my parents decided I was mature enough to be told that they had both undergone the switch—three years before. I pretended to take the news calmly, but I hated them passionately for not having told me at the time. They had disguised their stay in hospital with lies about a business trip overseas. For three years I had been living with jewel-heads, and they hadn’t even told me. It was exactly what I would have expected of them.
"We didn’t seem any different to you, did we?" asked my mother.
"No," I said—truthfully, but burning with resentment nonetheless.
"That’s why we didn’t tell you," said my father. "If you’d known we’d switched, at the time, you might have imagined that we’d changed in some way. By waiting until now to tell you, we’ve made it easier for you to convince yourself that we’re still the same people we’ve always been." He put an arm around me and squeezed me. I almost screamed out, "Don’t touch me!" but I remembered in time that I’d convinced myself that the jewel was No Big Deal.
I should have guessed that they’d done it, long before they confessed; after all, I’d known for years that most people underwent the switch in their early thirties. By then, it’s downhill for the organic brain, and it would be foolish to have the jewel mimic this decline. So, the nervous system is rewired; the reins of the body are handed over to the jewel, and the teacher is deactivated. For a week, the outward-bound impulses from the brain are compared with those from the jewel, but by this time the jewel is a perfect copy, and no differences are ever detected.
The brain is removed, discarded, and replaced with a spongy tissue-cultured object, brain-shaped down to the level of the finest capillaries, but no more capable of thought than a lung or a kidney. This mock-brain removes exactly as much oxygen and glucose from the blood as the real thing, and faithfully performs a number of crude, essential biochemical functions. In time, like all flesh, it will perish and need to be replaced.
The jewel, however, is immortal. Short of being dropped into a nuclear fireball, it will endure for a billion years.
My parents were machines. My parents were gods. It was nothing special. I hated them.
When I was sixteen, I fell in love, and became a child again.
Spending warm nights on the beach with Eva, I couldn’t believe that a mere machine could ever feel the way I did. I knew full well that if my jewel had been given control of my body, it would have spoken the very same words as I had, and executed with equal tenderness and clumsiness my every awkward caress—but I couldn’t accept that its inner life was as rich, as miraculous, as joyful as mine. Sex, however pleasant, I could accept as a purely mechanical function, but there was something between us (or so I believed) that had nothing to do with lust, nothing to do with words, nothing to do with any tangible action of our bodies that some spy in the sand dunes with parabolic microphone and infrared binoculars might have discerned. After we made love, we’d gaze up in silence at the handful of visible stars, our souls conjoined in a secret place that no crystalline computer could hope to reach in a billion years of striving. (If I’d said that to my sensible, smutty, twelve-year-old self, he would have laughed until he hemorrhaged.)
I knew by then that the jewel’s "teacher" didn’t monitor every single neuron in the brain. That would have been impractical, both in terms of handling the data, and because of the sheer physical intrusion into the tissue. Someone-or-other’s theorem said that sampling certain critical neurons was almost as good as sampling the lot, and—given some very reasonable assumptions that nobody could disprove—bounds on the errors involved could be established with mathematical rigour.
At first, I declared that within these errors, however small, lay the difference between brain and jewel, between human and machine, between love and its imitation. Eva, however, soon pointed out that it was absurd to make a radical, qualitative distinction on the basis of the sampling density; if the next model teacher sampled more neurons and halved the error rate, would its jewel then be "halfway" between "human" and "machine?" In theory—and eventually, in practice—the error rate could be made smaller than any number I cared to name. Did I really believe that a discrepancy of one in a billion made any difference at all—when every human being was permanently losing thousands of neurons every day, by natural attrition?
She was right, of course, but I soon found another, more plausible, defense for my position. Living neurons, I argued, had far more internal structure than the crude optical switches that served the same function in the jewel’s so-called "neutral net." That neurons fired or did not fire reflected only one level of their behaviour; who knew what the subleties of biochemistry—the quantum mechanics of the specific organic molecules involved—contributed to the nature of human consciousness? Copying the abstract neural topology wasn’t enough. Sure, the jewel could pass the fatuous Turing test—no outside observer could tell it from a human—but that didn’t prove that being a jewel felt the same as being human.
Eva asked, "Does that mean you’ll never switch? You’ll have your jewel removed? You’ll let yourself die when your brain starts to rot?"
"Maybe," I said. "Better to die at ninety or a hundred than kill myself at thirty, and have some machine marching around, taking my place, pretending to be me."
"How do you know I haven’t switched?" she asked, provocatively. "How do you know that I’m not just ‘pretending to be me’?"
"I know you haven’t switched," I said, smugly. "I just know."
"How? I’d look the same. I’d talk the same. I’d act the same in every way. People are switching younger, these days. So how do you know I haven’t?"
I turned on my side towards her, and gazed into her eyes. "Telepathy. Magic. The communion of souls."
My twelve-year-old self started snickering, but by then I knew exactly how to drive him away.
At nineteen, although I was studying finance, I took an undergraduate philosophy unit. The Philosophy Department, however, apparently had nothing to say about the Ndoli Device, more commonly known as "the jewel". (Ndoli had in fact called it "the dual," but the accidental, homophonic nickname had stuck.) They talked about Plato and Descartes and Marx, they talked about St. Augustine and—when feeling particularly modern and adventurous—Sartre, but if they’d heard of Godel, Turing, Hamsun or Kim, they refused to admit it. Out of sheer frustration, in an essay on Descartes I suggested that the notion of human consciousness as "software" that could be "implemented" equally well on an organic brain or an optical crystal was in fact a throwback to Cartesian dualism; for "software" read "soul." My tutor superimposed a neat, diagonal, luminous red line over each paragraph that dealt with this idea, and wrote in the margin (in vertical, bold-face, twenty-point Times, with a contemptuous two-hertz flash): irrelevant!