At long last, we return to the Venus-versus-Mars enigma of Episode III. I have already told you that Parfit somewhat sidesteps the question by simply denying the existence of Cartesian Egos, and thus saying that the question has no meaningful answer. But in his book he also refers quite often to what he terms “double survival”, which means essentially that he is simultaneously in two places at once. More than once, he writes that double survival is hardly equivalent to death (which would be no survival), and that the number two should not be conflated with the number zero! So what is he really saying? Is he saying that there is no answer to the question, or is he saying that in fact he has been doubled, and there are now two Derek Parfits?
It’s hard for me to figure this out since I think he says both things often enough that one could argue it either way. But where do I come down on this issue? I think I come down on the “two me’s” side. At first, this almost sounds as if I am embracing the Cartesian Ego theory, just imagining that the egg is cloned and two identical Cartesian Egos come to exist, one on Venus and one on Mars. But then SL #642 would start screaming, “Which one is me?” It sounds as if I haven’t answered the question at all, or as if I want to have my egg on Mars and eat it too, on Venus.
In order to regain some semblance of consistency, I have to return to SL #641’s theme in the dialogue, which is that the “I” notion is, fundamentally and in the end, a hallucination. Let’s let Episode III, my teleportation scenario with fresh copies on Venus and Mars and no copy left on Earth, apply to me instead of to Parfit. In that case, each of the new brains — the one on Mars and the one on Venus — is convinced that it is me. It feels just like it always felt to be me. The same old urge to say, “I am here and not there” zooms up in both brains as automatically as when someone taps my knee and my leg jerks upwards. But knee-jerk reflex or not, the truth of the matter is that there is no thing called “I” — no hard marble, no precious yolk protected by a Cartesian eggshell — there are just tendencies and inclinations and habits, including verbal ones. In the end, we have to believe both Douglas Hofstadters as they say, “This one here is me,” at least to the extent that we believe the Douglas Hofstadter who is right now sitting in his study typing these words and saying to you in print, “This one here is me.” Saying this and insisting on its truth is just a tendency, an inclination, a habit — in fact, a knee-jerk reflex — and it is no more than that, even though it seems to be a great deal more than that.
Ultimately, the “I” is a hallucination, and yet, paradoxically, it is the most precious thing we own. As Dan Dennett points out in Consciousness Explained, an “I” is a little like a bill of paper money — it feels as if it is worth a great deal, but ultimately, it is just a social convention, a kind of illusion that we all tacitly agree on without ever having been asked, and which, despite being illusory, supports our entire economy. And yet the bill is just a piece of paper with no intrinsic worth at all.
Trains Who Roll
In Chapters 15 through 18, I argued that each of us is spread out and that, despite our usual intuitions, each of us is housed at least partially in different brains that may be scattered far and wide across this planet. This viewpoint amounts to the idea that one can be in two places at once, despite our initial knee-jerk rejection of such a crazy-sounding thought. If being in two or more places at once seems to make no sense, think about reversing the roles of space and time. That is, consider that you have no trouble imagining that you will exist tomorrow and also the next day. Which one of those future people will really be you? How can two different you’s exist, both claiming your name? “Ah,” you reply, “but I will shortly be getting there, like a train pulling through different stations.” But that just begs the question. Why is it the same train, if in the meantime it has dropped some passengers off and picked others up, perhaps changed a car or two, maybe even its locomotive? It is simply called “Train 641”, and that’s why it is “the same train”. It’s a linguistic convention, and a very good one, too. It is a very natural convention in the classical world in which we exist.