Re: against UD+ASSA, part 1

From: Hal Finney <>
Date: Wed, 26 Sep 2007 14:04:52 -0700 (PDT)

Wei Dai writes:
> I promised to summarize why I moved away from the philosophical position
> that Hal Finney calls UD+ASSA. Here's part 1, where I argue against ASSA.
> Part 2 will cover UD.
> 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.

This is an interesting experiment, but I have two comments. First,
you could tighten the dilemma by having the mad scientist flip a biased
coin with say a 70% chance of coming up heads, but then he duplicates
you if it comes up tails. Now you have it that the different styles of
reasoning lead to opposite actions, while in the original you might as
well pick 0 in any case.

Second, why the proviso that the simulations are identical and
deterministic? Doesn't the reasoning (and dilemma) go through just as
strongly if they are allowed to diverge? You will still be faced with a
conflict where one kind of reasoning says you have your 91% subjective
probability of it coming up a certain way, while logic would seem to
suggest you should pick the other one.

But, in the case where your instances diverge, isn't the subjective-
probability argument very convincing? In particular if we let you run
for a while after the duplication - minutes, hours or days - there might
be quite a bit of divergence. If you have 91 different people in one
case versus 1 in the other, isn't it plausible - in fact, compelling -
to think that you are in the larger group?

And again, even so, wouldn't you still want to make your choice on the
basis of ignoring this subjective probability, and pick the one that
maximizes the chances for your survivors: as you say, the measure of
the outcomes that you care about?

If so, then this suggests that the thought experiment is flawed because
even in a situation where most people would agree that subjective
perception is strongly skewed, they would still make a choice ignoring
that fact. And therefore its conclusions would not necessarily apply
either when dealing with the simpler case of a deterministic and
synchronous duplication.

Hal Finney

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Received on Wed Sep 26 2007 - 18:26:43 PDT

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