Hal Finney wrote:
Imagine facing your copy, perhaps an exact copy whose mind is synchronized with yours, and seeing a coin flip which will determine which one is destroyed. Your measure will be halved. In a sense it will have no subjective effect, your thoughts and memories will be preserved in one of you. But in another sense you face a 50-50 chance of experiencing that mysterous effect of instant death. I think it would be scary. Logically, similar reductions of measure should be viewed in the same light.
As I'm sure many on the list are familiar, David Brin's "Kiln People" is an interesting science fiction treatment of similar issues.
In this story, a technology exists by which one may copy one's "standing wave" (forgive the cheesy pseudo-terminology) into a specially formed clay-based body. These duplicates, or "dittos", have a limited (24 hour) lifespan before they self-destruct. Different clay templates are manufactured to enhance different parts of the mind's functioning, so one can create dittos that are better at abstract thinking, or that have more tolerance to menial work, etc.
In this society, people create a variety of dittos on a daily basis to conduct their business in the world while they themselves avoid risk or stick to the more pleasant things. The dittos know exactly what to do as they are the exact personality and memories of the original up to the point of copying. They have a compulsion to return home prior to their self-destruction so their memories can be reintegrated with their original. (It wasn't clear, to me anyway, whether this compulsion was forced or whether it was the consequence of the dittos understanding that they would "die" if they didn't make it back to reintegrate.)
Brin's treatment of this scenario is well worth the read; it's like a novel-length thought experiment. One scene follows the internal dialogue of the protagonist as he enters the copying machine, and then the individual internal dialogues of his copies. There is initial continuity and then a divergence as each copy "discovers" which one he is and thus what he must do for the day. And of course, each one feels like he became that particular copy at random.
Some of the same issues about whether one should "care" about one's copies (and whether the copies should care about the original) are handled as well. In this story, though, since the dittos reintegrate their memories, they know they will eventually have the memories of the other copies, as well as what has happened with the original in the interim.
Neat stuff. There is a lot more along these lines, wrapped in a suspense/murder/mystery storyline (the protagonist is a detective.) The last third of the book gets a little dubious, though, but it is a good read overall nonetheless.