Re: QTI, SSI (fwd)

From: Marchal <>
Date: Tue May 18 06:33:43 1999

Russell Standish:
>This is precisely my point. SSA can apply to birth order, but it
>surely can't apply to subsequent concious moments.
>Bruno mentioned a "relative SSA". I suspect he is trying to say the same
>thing, but in a different way. How precisely would you define a
>relative SSA?

Here is the message of Nick Bostrom where he introduces briefly
the SSA (in this discussion list 13/04/99):

>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:

My feeling is that I agree with Russell. I cannot yet be sure of that
because of the lack in precision.
In particular I am not even sure we can apply SSA to birth order.

The difference I would make between absolute ("Bostromian") SSA and
SSA is that in the absolute case it seems that we can quantify
on the set of all "human beings" or "observers" or even on the
set of all conscious states. With the relative or
conditionnal case we quantify only on a set of continuations.
Exemple : in the quantum suicide experiment, or more easily in the
teleportation scheme you are supposed to be destroyed at place A and
reconstituted at place B. The absolute probability to find yourself at B
has no meaning, it is only the relative or conditionnal probability to
find yourself at B, knowing that you are at A "now" and knowing you will
be destroyed at A and reconstituted at B which makes possible to quantify
the indeterminisme.
P(B) has no meaning, but P(B/A) has.

James Higgo:
>Russell, here we disagree. A billion-year-old man has no more evidence of
>MWI than do his young contemporaries.

I don't understand why. COMP or MWI predict that from my first-person
perspective I will live much longer that any of my contemporaries.
If I live much more than my contemporaries I can take that as evidence
(not as a proof of course) that COMP or MWI or any theory wich predicts
that, is
correct. Here too I seem to agree with Russell.

I am not sure of the order of the posts (thanks to my amnesic E-MAILER).
I guess here is your answer, James:

>For anyone else, the sight of a billion-year-old man
>would not prove or disprove the Quantum Theory of
>But for you, at age 1 billion, the probability that you
>would reach a billion, given QTI, is one. And the
>probability that you would reach a billion given not-QTI
>is very tiny. So it is not unreasonable to believe QTI.
>I'm not sure you can really quantify this.
>On another note, the SSA is a dangerous to use
>when the Self is not a representative sample - the
>Self is immortal, whereas everyone else is not.

Do you agree with the following rephrasing:
"The first-person is immortal, whereas any third person is not." ?

Jacques M Mallah has said:
> Um ... what the hell did any of that have to do with immortality?
>I'll tell you what - nothing. Only by looking at the measure distribution
>can we find out about mortality.

And I have answered:
I agree. That is why a computationnalist should define a relative
measure distribution on the set of computationnal histories. But once you
accept the probability argument of the preceding posts, "immortality" is
qualitatively much more plausible than mortality.

I would like to add this "exercice": Show that for any running program
there is aleph-one never stopping possible continuations and only aleph-
zero possible stopping continuations. That is why immortality is more
probable than mortality.

Received on Tue May 18 1999 - 06:33:43 PDT

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