Re: predictions

From: Wei Dai <>
Date: Tue, 7 Apr 1998 11:16:03 -0700

On Mon, Apr 06, 1998 at 11:38:08PM +0000, Nick Bostrom wrote:
> When you make your decision at time 1 you don't need any
> probabilities, since you already know with certainty what's going to
> happen given that you take a certain proposed action (and provided
> you have the conputational ability to derive this). You know that if
> you take such and such an action, then there will be n copies of
> yourself at some later time. In my opinion there is no further fact
> as to which one of these copies you will "really" turn out to be;
> you'll be all of them.

I think this is one possible approach for a new decision theory. I would
call this the outside view approach. You know with certainty that if you
take such and such an action, how you'll affect each and every universe,
and you make decisions based on the total effects your actions would have.
I'm not sure however, how you would reconcile this theory with the fact
that in the outside view every choice is always made in every
possible way. I'm not saying you can't, but this seems to be a problem
that needs to be solved before one could adopt an outside view
approach to decision theory.

The alternative to the outside view approach is the inside view approach.
Here your actions do not affect the universes, but only your own
perceptions. If you lay out all of your possible future perceptions in a
tree structure, you can think of your decisions as choosing which branches
to experience. The biggest problem I have with this approach is how to
handle the fact that people forget things, so perceptions do not just
branch but also merge. I'll say more about this in another thread.

> Also, it helps you make predictions at time 2, provided that you
> haven't yet opened your eyes and seen how the coin landed. (If you
> already know how it landed, then the issue is of course settled
> and the probability is 1 or 0).

I'm not sure I understand you. If you're adopting the outside view
approach (which your earlier paragraph seems to suggest), then before you
open your eyes you know with certainty that there are two of you in the
universe where the coin landed heads and one of you in the universe where
the coin landed tails. Probabilities simply do not enter into the picture.
Received on Tue Apr 07 1998 - 11:17:06 PDT

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