I was working on an essay on the nature of thought experiments about
copying, but it got bogged down, so I will make this short. I am trying
to analyze it based on evolutionary considerations. Copying is much like
biological reproduction and we can expect many of the same effects in
a society in which copying is a long-standing and widely used technology.
The most important effect is that making copies will be desirable.
Just as genes try to reproduce themselves, so will people once that
becomes possible, and for the same reason: successful reproducers occupy
more of the universe's resources (i.e. have higher measure) and so these
habits tend to become more widespread.
When we consider thought experiments involving copies, it is important to
understand these effects. It is truly different to make a set of copies
than to experience a probabilistic event. Making copies increases your
measure in the world; flipping a coin does not. The decisions you will
make in the two cases are different as a result.
One thought experiment was to consider two choices: flipping a coin and
being tortured if it came up a certain way; versus making several copies
and having one of them be tortured. Assuming the copies are all going to
survive, clearly the latter would be the one selected by evolution.
But note that this is still true if we reverse the probabilities: a
small probabilistic chance of being tortured, versus making one copy
(so there are two of you) and having one of them being tortured. There,
too, I think the evolutionary approach would encourage making copies.
Copying is such a bonus that it swamps consideration of quality of life.
In a world where people have adapted to copying, they would work as
hard to make a copy as they would in our world to avoid dying (each one
changes measure by plus or minus 100%).
It might be objected that this approach does not shed much light on what
our expectations would be or should be about what we will experience when
we go through these transformations. I agree with the perspective that
there is truly no "fact of the matter" about what it is like to have one
of these things happen. All we can really do is look at the experiences
and memory of each person, at each moment. No one will disagree about
what each person at each moment remembers and how many of them there are.
That is really all there is, factually.
Our attempt to make these novel situations fit our conventional
expectations don't work because we currently have an implicit assumption
of mental continuity which is violated by copying experiments. There
really is no meaningful and non-arbitrary way to map our current ways
of thinking about the future to a world where copying is possible.
But what we can do is really just as good: we can predict how people
would and should behave. Which preferences will they have in these
thought experiments? How hard will they work to achieve one option versus
another? Evolutionary theory provides guidelines and examples we can use
to understand how people will behave if and when copying becomes possible.