Some comments

From: Marchal <>
Date: Mon May 10 03:35:37 1999

Hi Nick, Gilles, Jacques and all Everythingers,

Nick Bostrom wrote:
>The Self-Sampling Assumption (SSA), the idea that you should reason
>as if you were a random sample form the set of all observers,
>underlies many of the discussions we have had on this list. About
>half a year ago I discovered some paradoxical consequences of this
>assumption. It seems to imply that weird backwards causation and
>psychokinesis(!) is feasible in our world. In this small paper I
>describe these possible counterexamples and discuss whether they
>really are as paradoxical as they appear at first blush:

I think your paper is essentially correct, but the notion of "set of all
observers" is far from clear to me. In my work (cf signature below)
I use a much weaker *necessarily conditionnal (or relative)* "Self-
Sampling Assumption".

Gilles Henry wrote:
>But a conscious being cannot exist without being
>perturbated by its environment (in fact we are conscious BECAUSE we are
>constantly interacting with our environment).

This seems to me to be in contradiction with any standart
account of the dream phenomenon.
I just mean you cannot believe what you say here without being
with computationnalism.

Jacques M Mallah quoted a letter by Don N Page (adressed to Jacques M
> Thanks for your message. Jerry Finkelstein had asked me how the
>evidence of one's living to 2100 would be any diferent from the
>evidence of
>getting any other low-measure result, which would occur in MWI. (I
>suppose the
>only difference I see is that one would not be alive to be aware of the
>contrary evidence in other worlds.) But this got me to realize that
>the maverick worlds in which one would live to 2100 certainly exist in the
>they would have so low a measure that one experiencing it would be
>a very low typicality observation, which if one counts the typicality as
>likelihood, as I argue one should do in my Sensible Quantum Mechanics
>would be evidence agains the MWI just as strong as against the
> So I agree with your criticism.

So, Jacques, you succeed in convincing Don Page against Quantum
Immortality !
I would not be proud of that!

It seems that you (and Don Page now) reason like that :

Maverick worlds in which I am alive in 2100 are rare, so the probability
I feel alive in 2100 is low.
But, at least with computationnalism (or "comp" if you prefer: I mean the
hypothesis that I can survive with a digital *body*), I can only compute
the probability from a distribution defined on the worlds in which I
There is no sense in counting worlds in which I do not survive.
Typicality or likelihood are relative to the observer.

Of course the fact I feel alive in 2100 would not be necessarily a
confirmation of the MWI of Quantum Mechanics, it could be *just* a
confirmation of the MWI of computationalism.

You don't believe in comp-immortality, do you ?

Tell me if you agree at least with the weaker proposition:

     COMP + HE ====> immortality

where HE is the (extravagant) hypothesis saying that a real concrete
universal dovetailer (generating and executing all programs) exists
in our "universe".
If you agree, my only task will be to show you how to eliminate HE.


 Bruno MARCHAL Phone : +32 (0)2 6502711
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Received on Mon May 10 1999 - 03:35:37 PDT

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