Re: against UD+ASSA, part 1

From: Bruno Marchal <>
Date: Wed, 26 Sep 2007 17:07:40 +0200

Le 26-sept.-07, à 15:34, Stathis Papaioannou a écrit :

> On 26/09/2007, Wei Dai <> wrote:
>> Consider the following thought experiment. Suppose your brain has been
>> destructively scanned and uploaded into a computer by a mad
>> scientist. Thus
>> you find yourself imprisoned in a computer simulation. The mad
>> scientist
>> tells you that you have no hope of escaping, but he will financially
>> support
>> your survivors (spouse and children) if you win a certain game, which
>> works
>> as follows. He will throw a fair 10-sided die with sides labeled 0 to
>> 9. You
>> are to guess whether the die landed with the 0 side up or not. But
>> here's a
>> twist, if it does land with "0" up, he'll immediately make 90
>> duplicate
>> copies of you before you get a chance to answer, and the copies will
>> all run
>> in parallel. All of the simulations are identical and deterministic,
>> so all
>> 91 copies (as well as the 9 copies in the other universes) must give
>> the
>> same answer.
>> ASSA implies that just before you answer, you should think that you
>> have
>> 0.91 probability of being in the universe with "0" up. Does that mean
>> you
>> should guess "yes"? Well, I wouldn't. If I was in that situation, I'd
>> think
>> "If I answer 'no' my survivors are financially supported in 9 times
>> as many
>> universes as if I answer 'yes', so I should answer 'no'." How many
>> copies of
>> me exist in each universe doesn't matter, since it doesn't affect the
>> outcome that I'm interested in.
>> Notice that in this thought experiment my reasoning mentions nothing
>> about
>> probabilities. I'm not interested in "my" measure, but in the measures
>> of the outcomes that I care about. I think ASSA holds intuitive
>> appeal to
>> us, because historically, copying of minds isn't possible, so the
>> measure of
>> one's observer-moment and the measures of the outcomes that are
>> causally
>> related to one's decisions are strictly proportional. In that
>> situation, it
>> makes sense to continue to think in terms of subjective probabilities
>> defined as ratios of measures of observer-moments. But in the more
>> general
>> case, ASSA doesn't hold up.
> There is an asymmetry here because you are reasoning about a part of
> the multiverse which isn't duplicated. If both you and all your
> survivors were duplicated together, or if you were only interested in
> some selfish reward you would obtain in the event of a "0", that would
> change the problem.

> A discrepancy between 1st person/ 3rd person POV
> is also seen in QS experiments.

Important point, I agree. Like I agreed with Stathis' answer to Youness
(I think) for helping to distinguish ASSA and RSSA. At least formally
RSSA implies immortality, where ASSA does not.
Of course the kind of immortality you get from comp (and thus RSSA-like
theory, like pure QM also) is not necessarily resembling the kind of
"wishful type of immortality" associated with some religion.


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Received on Wed Sep 26 2007 - 11:10:01 PDT

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