1. Am I me or just a copy?


Derek Parfit wasn’t the first to discuss the metaphysical perplexities surrounding teleportation, fission, fusion, and the like, but his discussions of them were often riveting. The passage above continues:


Can a person really be teleported to Mars, or anywhere else, in this way? The question is completely vexed. Assuming that the relevant physical procedures can be carried out, some philosophers are prepared to regard this as a genuine form of transport: the “fastest way of travelling,” as Parfit aptly puts it (p. 200). Others, however, consider this nothing so much as a way of killing oneself. These latter believe that the people who emerge from these “transporters” are not identical to the ones who entered but are just duplicates who look and act like them, and who unsuspectingly think they are them. The truth, they aver, is that the ones who entered died the instant the machines destroyed their brains and bodies, and the ones who emerged are mere copies.

It’s maddeningly unclear where the truth lies in this matter. Both parties to the controversy appear to have sensible arguments on their side and philosophers are completely divided on the issue.
In what follows, I will assume that this impasse is familiar by way of background context. I don’t really plan on examining it here because there seems to be little prospect of settling the debate a priori, which is how it is usually conducted. What I wish to consider instead is whether the controversy might be resolved empirically. Assuming that I had one of these teleporters at my disposal, could I not simply try it out for myself and see if the thing worked? Suppose, in particular, that I get into the machine, press the button, and promptly find myself waking up on Mars, much as Parfit describes above. Would that prove, if only to my own satisfaction, that I had indeed been transported to Mars?

I don’t know of any discussion of this question in the literature, e.g., Parfit himself does not discuss it anywhere in his book. The question is more interesting than may at first appear. Thus, a natural first thought is that the answer is no, since you wouldn’t be able to tell, should you awaken on Mars, whether you were real or copy, and thus whether the machine had worked or failed. So you’d be in no position to know that the machine had worked, even if it did. More generally, one might think that the reality (or otherwise) of teleportation cannot be established empirically any more than it can be established a priori. I will examine this sort of thinking below, however, and suggest that it is not quite right. In particular, I will argue that, if teleportation really works, then, under certain conditions to be specified, you can verify as much by trying a teleporter out for yourself. You’d find yourself waking up on Mars and you’d know that you were you and that the machine had worked.