Re: David Deutsch on probability in the MWI

From: Wei Dai <weidai.domain.name.hidden>
Date: Mon, 7 Jun 1999 18:34:34 -0700

> > http://xxx.lanl.gov/pdf/quant-ph/9906015

I just read this paper and it seems to have a pretty big problem. On page 5
it says:

"For convenience, let us consider games in which the measured value of X^
is numerically equal to the utility of the payoff, measured on some
suitable utility scale. And let us consider only players for whom the
utilities of the possible payoffs can be assigned so as to have an
additivity property, namely that the player is indifferent between
receiving two separate payoffs with utilities x1 and x2, and receiving a
single payoff with utility x1+x2."

It's not completely clear to me whether the second assumption (additivity)
is also "for convenience". The conclusion of the paper seems to depend on
this assumption and I could not see how to generalize the argument to
remove the dependency. If it really is a fundamental assumption for the
paper, then the conclusion would seem to apply only to hypothetical people
whose utilities just happen to satisfy the addititivity property.

BTW it's easy to see why these people don't exist. Additivity implies that
you either prefer two left shoes to a matched pair, or you prefer two right
shoes to a matched pair, or you are indifferent between all three choices.
Received on Mon Jun 07 1999 - 18:35:52 PDT

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