Stathis Papaioannou writes:
> That is the basic idea behind these thought experiments with copies: as a 
> more easily understood analogy for what happens in the multiverse/plenitude.

I don't agree, and in fact I think the use of copies as an analog for
what happens in the multiverse is fundamentally misleading.  If it were
not, you could create the same thought experiments just by talking about
flipping coins and such.

What is the analog, in the multiverse, of pushing a button to make a copy?
When faced with the chance of torture, you are going to push a button
to make a copy.  What does that correspond to in the multiverse?

The closest I can suggest is flipping a coin such that you don't get
tortured if it comes up heads.  Well, that destroys the whole point of
the thought experiment, doesn't it?  Of course you'll flip the coin.
Anyone would.

Pushing a button to make a copy is completely different.  That's why we
have so much disagreement about what to do in that case, while there
would be no disagreement about what to do if you could flip a coin to
avoid being tortured.  That in itself should be a give-away that the
situations are not as analogous as some are suggesting.

I would suggest going back over these thought experiments and substitute
flipping coins for making copies, and see if the paradoxes don't go away.

I believe that many of the paradoxes in the copy experiments are because
people do not grasp the full meaning of what copying implies.  They are
thinking very much in the lines Stathis suggests, that it is a variant on
flipping a coin.  But it's not.  Copying is fundamentally different from
flipping a coin, because copying increases measure while coin flipping
does not.

Measure is crucially important in multiverse models because it is the only
foundation for whatever predictive or explanatory ability they possess.
Choosing to overlook measure differences in analyzing thought experiments
inevitably leads to error.  Treating copying like coin flipping is just
such an error.  If you would instead think through the full implications
of copying you would see that it is completely different from flipping
a coin.  The increase of measure that occurs in copying manifests in the
world in tangible and obvious ways.  Its phenomenological consequences are
no less important.  These considerations must be included when analyzing
thought experiments involving copies, otherwise you are led into paradox
and confusion.

Hal Finney

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