Prestige and the nature of self

[sqbr]

I saw "The Prestige" recently (after distantcam bugging me to see it for ages) and it was awesome. What follows are some VERY spoilery thoughts which you SHOULD NOT READ if you haven't seen the film. They're not about the film per se, but were inspired by a major plot point.

*SPOILER* *SPOILER* *SPOILER* *SPOILER*

*SPOILER*

So, in the film Danton has set up his stage so that a copy of him is made, and then immediately afterwards one of the versions of him is killed. At the end of the film he says "I never knew if I was going to be the one who lived or the one who died".

distantcam and I got into a discussion about whether or not this statement makes any sense. Unfortunately it was very late so I can't remember distantcam's argument well enough to do it justice but I'll try, and will let him explain himself better in the comments if he likes.

So. Just before the lever is switched we have one Danton, lets call him DantonA. He thinks to himself "I wonder if I will be the one who lives or the one who dies". Just afterwards we have DantonB1 and DantonB2, both of whom are exact duplicates of DantonA and have all his memories. DantonB1 appears in exactly the same position as DantonA, and is immediately killed. DantonB2 appears about 100m away, and goes on to become the only Danton (for the next 24 hours or so anyway)

distantcam's argument: (I think) by definition, the one who survives is, and always was DantonA, but he had a 50% chance of being DantonB1 and dying. Beyond that I don't 100% remember it.

My argument: every moment the person we are (DantonA) is destroyed, and a new almost identical person (DantonB) is created in the same place. We plan our lives as if we are the same person as our future selves, and make that future self's happiness a priority, but strictly speaking we are not them. However we are "the same person as them" in a more broad, commonsense sense. In my opinion, DantonB1 and DantonB2 are not the same person as each other, but depending on how you think about it they are either both or neither the same person as DantonA. (yes, usually "the same person as" is commutative, but that's because usually our notion of self doesn't have to deal with exact duplicates)

First let us consider what would happen if there was no cloning device, and Danton simply died after pulling the lever. DantonA thinks "I wonder if I will die?" and then turns into DantonB, thinks "crap, yep, going to drown", then drowns. In one sense the person who is DantonA doesn't drown because at that point there is no DantonA, only DantonB. But in the usual way of thinking about things, DantonA=DantonB, and so has a 100% chance of being "the one who drowns".

Now consider the world of the film. DantonA thinks "I wonder if I will die?". He then splits into DantonB1 and DantonB2. DantonB1 thinks "crap, I am the one who drowns" and drowns. DantonB2 thinks "Yay! Not the one who drowns!". They are both equally right, they both remember being DantonA and both think of themselves as being the same person as DantonA, only slightly in the future. Thus either we think of DantonA (the one who thought "I wonder if I will die?") as being already destroyed and so the question is meaningless, or they are both "the same person" as DantonA and so a person who is DantonA (but slightly in the future) always drowns, and a person who is DantonA (but slightly in the future) always lives.

An example I think illustrates my point: suppose neither of them died, but DantonB1 appeared the the left and DantonB2 to the right. Before pulling the lever DantonA thinks "I wonder if I will appear on the right or the left?". A moment later, DantonB1 appears and thinks "Ooh, I appeared on the left" while DantonB2 appears and thinks "Ooh, I appeared on the right". Which of them is the same person as DantonA? Does it make sense for Danton to ask himself "Will I appear on the left or the right?"? I say no, and that the question is equivalent to "Will I drown or not?".

Third POV I just thought of: DantonA=DantonB1, since they are physically continuous. Therefore DantonA, the person who thinks "I wonder if I will drown?", has an 100% chance of dying, and the surviving copy DantonB2 is just a clone who thinks he is DantonA (only slightly in the future) but is actually a totally different person.

So, make any sense to people? Or too philosophical and tl;dr? Any opinions?

Comments

[shrydar.livejournal.com]

hehe.

But yes, I think you're on to something there. His mental model seemed to be something along the lines of "a clone is created, then the one of us is selected at random for transportation."

I'm glad the film didn't appear to be going out of it's way to claim Danton's world view was necessarily prescriptive (cf comments below about him being off his rocker :).

[alias_sqbr]

So, looks like we do all actually agree with each other, but not with Danton, who was caraaazy.