Re: FIN Again (was: Re: James Higgo)

From: Jacques Mallah <>
Date: Thu, 30 Aug 2001 17:51:46 -0400

>From: "Jesse Mazer" <>
>I don't understand your objection. It seems to me that it is perfectly
>coherent to imagine a TOE which includes both a universal "objective"
>measure on the set of all observer-moments and also a relative conditional
>probability which tells me what the probability is I'll have experience B
>in the future if I'm having experience A right now.

    "You" is just a matter of definition. As for the conditional effective
probability of an observation with characteristics A given that it includes
characteristics B, p(A|B), that is automatically defined as p(A|B) = M(A and
B) / M(B). There is no room to have a rival "relative conditional
probability". (E.g. A = "I think I'm in the USA at 12:00 today", B="I think
I'm Bob".)

>In statistics we have both absolute and conditional probability, so what's
>wrong with having the same thing in a TOE?

    In fact there is no choice but to have conditional probability - as long
as it's the one that the absolute measure distribution automatically

>I suppose one objection might be that once we have an objective measure, we
>understand everything we need to know about why I find myself having the
>types of experiences I do

    Indeed so.

>and that defining an additional conditional probability measure on the set
>of all observer-moments would be purely "epiphenomenal" and inelegant. Is
>that what your problem with the idea is?

    It's not just inelegant. It's impossible, if by "additional" you mean
one that's not the automatic one.

>self-sampling assumption--what does it mean to say that "I" should reason
>as if I had an equal probability of being any one of all possible

    It means - and I admit it does take a little thought here - _I want to
follow a guessing procedure that, in general, maximizes the fraction of
those people (who use that procedure) who get the right guess_. (Why would
I want a more error-prone method?) So I use Bayesian reasoning with the
best prior available, the uniform one on observer-moments, which maximizes
the fraction of observer-moments who guess right. No soul-hopping in that
reasoning, I assure you.

>if I am about to step into a machine that will replicate one copy of me in
>heaven and one copy in hell, then as I step into the imaging chamber I will
>be in suspense about where I will find myself a moment from now, and if the
>conditional probability of each possible future observer-moment is 50%
>given my current observer-moment, then I will interpret that as a 50/50
>chance that I'm about to experience torture or bliss.

    That depends on the definition of "you". In any case, one copy will be
happy (the one partying with the succubi in hell) and the other will be sad
(the one stuck hanging out with Christians). So your utility function
should be about even. I assume you'd care about both future copies at that

>Surely you agree that there is nothing *mathematically* incoherent about
>defining both absolute and conditional probability measures on the set of
>all observer-moments. So what's your basis for calling the idea "crazy?"

    I've explained that in other posts, but as you see, the idea is indeed
mathematically incoherent - unless you just mean the conditional effective
probability which a measure distribution defines by definition. And _that_
one, of course, leads to a finite expectation value for ones's observed age
(that is, no immortality).

                         - - - - - - -
               Jacques Mallah (
         Physicist / Many Worlder / Devil's Advocate
"I know what no one else knows" - 'Runaway Train', Soul Asylum
         My URL:

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Received on Thu Aug 30 2001 - 14:52:53 PDT

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