Re: Decision theory

From: Wei Dai <>
Date: Tue, 29 Dec 1998 15:08:54 -0800

On Tue, Dec 29, 1998 at 02:16:41PM -0500, Jacques M Mallah wrote:
> Since I explained why it should still work, how would an example
> help? You can just take any non-MWI example and restate it in the MWI
> language. OK, I'll be extra nice and do it myself.

I think I understand what you're saying now. You are suggesting that we
act as if we have free will and can select amongst alternative
wavefunctions, even if we don't believe it's true metaphysically.
This approach might work for the MWI, but not with a theory that has
no free parameters, since there would be no alternative meta-universes to
select amongst.

I realize now the problem with decision theory is really about the absence
of free parameters in a physical theory, and the problem is practical, not
metaphysical. So let me redescribe it. Decision theory depends on a
physical theory to compute the consequences of actions, statements like
"If I do X, Y will happen." But a physical theory with no free parameters
cannot be used for this purpose. Either the theory says I in fact do X, in
which case Y will happen but it's the same Y for every X, or it says in
fact I don't do X, in which case it doesn't give any predictions about Y
at all.
Received on Tue Dec 29 1998 - 15:11:41 PST

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