I Am a Strange Loop - Douglas R. Hofstadter [190]
If it had been recounted sufficiently smoothly, we might not have been able to resist the thought that this body, the Mars-borne one, is really Derek Parfit. Indeed, Derek Parfit the skilled philosopher–storyteller might even have gotten us to imagine that the earthbound body with the damaged heart was merely a pretender to the Unique Soul linked by birth and by divine decree to the name “Derek Parfit”.
Teleportation of a Thought Experiment across the Atlantic
It seems that the way in which a science-fiction scenario is related is crucial in determining our intuitions about its credibility. This is a point that my old colleague and friend Dan Dennett has made many times in his discussions of philosophers’ crafty thought experiments. Indeed, Dan calls such carefully crafted fables intuition pumps, and he knows very well whereof he speaks, since he has dreamt up some of the most insight-providing intuition pumps in the field of philosophy of mind.
And I have to say that as I was typing Parfit’s story from his 1984 book into this chapter, a little voice murmured softly to me, “Say, doesn’t this remind you of Dan’s foreword to The Mind’s I, his ingenious teleportation fantasy that drew so many readers to our book when it came out in 1981?” And so after the Parfit story had been all typed in, I pulled a copy of The Mind’s I off my shelf and reread its first few pages. I have to say that my jaw fairly dropped. It was exactly the same fantasy, only with planets reversed and sexes reversed, and told in a more American style. There was exactly the same bipartite structure, the first part featuring a “Teleclone Mark IV” that destroyed the original, and the second part featuring a newand-improved version (“Mark V”) that preserved the original.
What can I say? I love both of these stories, one from each side of the Atlantic, whether one is a “clone” of the other or their pedigrees are independent (though that seems unlikely, since The Mind’s I is in Parfit’s bibliography). In any case, now that I’ve got this little matter off my chest, I’ll continue with my commentary on Parfit’s provocative tale (and also, of course, on Dan’s, thanks to the referential power of analogy).
The Murky Whereabouts of Cartesian Egos
The key question raised by Parfit’s tale is this: “Where is space voyager Derek Parfit really, after the teletransportation has taken place in Episode II?” Put otherwise, which of the two claimants to being Parfit really is Parfit? In Episode I, Parfit the storyteller plants a most plausible-seeming answer, but then in Episode II he just as plausibly undermines that answer. At this point, you can probably almost hear Strange Loop #642 intensely identifying with the space traveler and screaming out, “Which of the two would I be?”
To my mind, one cannot claim to have said anything significant about the riddle of consciousness if one cannot propose (and defend) some sort of answer to this extremely natural-seeming and burning question. I think that by now you know my answer to the question, but maybe not. In any case, I’ll let you ponder the issue for a moment, and meanwhile, I’ll go on to tell you more or less how Parfit sees the matter.
This issue lies at the very core of Parfit’s book, and the explanation of his position occupies about a hundred pages. The key notion to which he is opposed is what he dubs “Cartesian Pure Ego”, or “Cartesian Ego”, for short. To put it in my words, a Cartesian Ego constitutes one exact quantum of pure soul (also known as “personal identity”), and it is 100 percent indivisible and undilutable. In short,