Re: Decision theory

From: Jacques M Mallah <>
Date: Fri, 1 Jan 1999 17:41:11 -0500

        Happy new year, everyone!

On Thu, 31 Dec 1998, Wei Dai wrote:
> On Wed, Dec 30, 1998 at 04:41:47PM -0500, Jacques M Mallah wrote:
> > Certainly any theory with no free parameters will predict many
> > cases in which a being like you will be faced with that decision, and in
> > some of them he will make one decision, in the rest he will make the
> > other. You can find out which of those cases you are in by making the
> > decision, and you can make the decision because the theory predicts the
> > results for both cases. Of course there must then be a small chance that
> > a 'random factor' might cause you to make the 'wrong' decision; QM
> > certainly predicts that there is such a chance, ditto a theory with 'all
> > possible structures'.
> I think you're suggesting that we think of decisions as selecting which of
> the you-like beings is really you, instead of as changing the universe
> somehow. This seems like a promising approach, and I've tried it too, but
> I haven't figured out how it can be formalized. It may require a
> different formal framework from "classical" decison theory.

        I don't see the problem. You were right when you said the problem
is a practical one: if it is impossible to calculate the effects of a
decision because that decision is physically impossible according to a
theory with no free parameters, that's a problem. I don't see that
problem ever occuring. In order to have no free parameters, the price
that a theory has to pay is precisely that all possible courses of action
will occur.
        Or to put it another way, even if the universe as a whole has no
free parameters, one is still free to consider a subsystem and has free
parameters available to specify what subsystem one chooses to look at.
        The bottom line is still that the only thing that matters is the
ability to calculate the effect of the decision.

                         - - - - - - -
              Jacques Mallah (
       Graduate Student / Many Worlder / Devil's Advocate
"I know what no one else knows" - 'Runaway Train', Soul Asylum
            My URL:
Received on Fri Jan 01 1999 - 14:43:17 PST

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