No one cares about the man in the box

Christopher Nolan's The Prestige (2006 ) is both a wonderful film and the source of a provocative set of thought experiments about personal identity. I'd like to talk about a few of the movie's philosophical implications of the film and ask some questions, but I should first warn you that spoilers lie ahead.

David Bowie delivers a delightfully quirky performance as the scientist and inventor Nikola Tesla (1856-1943). Surely in both character and actor we have here the nearest thing to science fiction that real life humanity has to offer!

Tesla builds a fantastic machine for the magician Robert Angier (played by Hugh Jackman), who is desperate to duplicate the astonishing feat of his arch-rival Alfred Borden (Christian Bale). Somehow Borden is able to convince an audience that he has transported himself across the stage in a mere instant. Angier (wrongly!) thinks that one of Tesla's machines is responsible, so he wants one for himself.

But the machine he receives doesn't merely duplicate Borden's trick. It duplicates Angier himself! After the Tesla lightning plays over his body, Angier is apparently unaffected--except that a second Angier appears some distance away. Now that's magic!

Suppose we're wondering just what this machine does. Consider the following possibilities:

(1) The machine creates an exact duplicate of Angier some distance away from the orginal Angier, who is otherwise unaffected by the machine and simply remains where he was. Call this case Duplication.

(2) The machine transports Angier some distance away from his original position and then creates an exact duplicate of him in that position. Call this Transport and Duplication.

(3) The machine replaces Angier with two exact duplicates of himself, one in his original position and the other some distance away. Call this one Fission.

I'd argue that the film favors (1), since it jives quite nicely with the earlier version of the trick wherein Angier must hide under the stage while his body double receives the accolades of the audience. And it's also an extension of the film's opening trick with the bird, too, in which the original bird is killed and then replaced by an exactly similar one. But that's not really my point here. Instead, I want to suggest that although these initially appear to be three distinct options, the differences among them become blurred upon reflection.

Angier says, "It took courage to climb into that machine every night... Not knowing if I'd be the Prestige.... Or the man in the box." But what is it that he doesn't know? Each of the two men thinks that he is "the real Angier." Yet they cannot both be Angier, notwithstanding Tesla's earlier remark that "they are all your hat, Mr. Angier." You see, identity is a transitive relation, so if Angier 1 is the original Angier and Angier 2 is the original Angier, then Angier 1 is Angier 2. And obviously that isn't the case, since there are two of them, and one lives and one dies. (In the first use of the machine, the Angier who remains shoots the Angier who travels, while in later uses it's the Angier who remains who is dropped into the box and drowns.)

So, if they cannot both be identical to the Angier who steps into the lightning, how do we answer Angier's question? Are we asking about the causal connection between the original Angier's body and the bodies of Angier 1 and Angier 2? Or are we asking about psychological continuity rather than bodily continuity? What's the difference between a machine that transports people and a machine that destroys and then duplicates people? (This question will be familiar to Star Trek fans....) In the end, does it matter whether the machine works in way (1), (2), or (3)? Is there really a difference?

Note that this problem isn't merely a result of the obvious fact that we don't understand how an incomprehensible fictional machine works. The deeper problem is that we don't understand exactly what it is to be a person and to be the same person when such odd things are going on. But do we understand such matters in ordinary cases? Perhaps not. And there are odd cases in real life as well as in sf.