Re: quantum suicide = deadly dumb

[Wei Dai]

On Thu, Dec 10, 1998 at 03:20:58PM +0100, Gilles HENRI wrote:
> maybe the decision theory itself (I must confess that my only knowledge of
> it comes from what Wei writes here) is somewhat metaphysical because it
> assumes that an individual can actually change the evolution of the world
> ("acts upon it"). In any model (not only MWI) where human beings are
> nothing but rather complicated physical systems, free will is an illusion.
> They evolve simply (including in their "choices") following the physical
> laws. So you can theoretically determine what would be the "best" choice
> following some criteria, but you are never certain that a given physical
> system will follow this way. In MWI, you can also calculate a best way, but
> you are certain that other ways will be followed as well. In "one world
> interpretation", you can try to programm a system (or a brain") to maximise
> the probability of evolving along a "good" way, but I think it is also true
> in MWI (maximise the number of "worlds" where the "good" way is followed).

But in the MWI, you can't maximize anything since all of the measures are
predetermined by boundary conditions.

I agree the problem is with decision theory, and that's why I suggest we
find a new decision theory rather than reject the MWI. I think this is
serious and of interest to more than just economists, because decision
theory appears to be the only justification we have for Bayesian
probability theory. Probability theory was invented for gambling and its
axioms are still justified by showing that they lead (via decision theory)
to reasonable behavior. Without a viable decision theory, an MWIer would
have to either give up probability theory or accept it as a given without
justification. Then it won't even be clear what probabilities mean, since
they'll just be useless numbers.

Re: quantum suicide = deadly dumb

[Gilles HENRI]

>On Wed, Dec 09, 1998 at 08:12:38PM -0500, Jacques M. Mallah wrote:
>>  On the contrary, it's the same.  That is easy to prove: suppose
>> the MWI was false but assume the universe is spacially infinite, so there
>> are other people like you in distant galaxies.  Clearly they have no
>> bearing on what you do, so you should make the usual decisions, including
>> of course any suicide decisions.  It is no different in the MWI; the only
>> difference is that the others are in different parts of wavefunction
>> configuration space, rather than regular space.
>
>Unfortunately because currently accepted decision theory makes some
>metaphysical assumptions, it can be compatible with a spacially infinite
>universe but not with MWI. Basicly decision theory depends on the idea of
>alternate realities and the notion that an individual chooses the actual
>reality among the alternatives as he makes decisions and acts upon them.
>But according to MWI, all alternatives are real and have predetermined
>measures.
>
>I can't figure out how to apply decision theory with the MWI. If you can,
>show us how, and please include an example.

maybe the decision theory itself (I must confess that my only knowledge of
it comes from what Wei writes here) is somewhat metaphysical because it
assumes that an individual can actually change the evolution of the world
("acts upon it"). In any model (not only MWI) where human beings are
nothing but rather complicated physical systems, free will is an illusion.
They evolve simply (including in their "choices") following the physical
laws. So you can theoretically determine what would be the "best" choice
following some criteria, but you are never certain that a given physical
system will follow this way. In MWI, you can also calculate a best way, but
you are certain that other ways will be followed as well. In "one world
interpretation", you can try to programm a system (or a brain") to maximise
the probability of evolving along a "good" way, but I think it is also true
in MWI (maximise the number of "worlds" where the "good" way is followed).

Gilles