RE: Measure, Doomsday argument

From: Jesse Mazer <lasermazer.domain.name.hidden>
Date: Mon, 20 Jun 2005 19:41:24 -0400

>From: Quentin Anciaux <quentin.anciaux.domain.name.hidden>
>To: everything-list.domain.name.hidden
>Subject: Measure, Doomsday argument
>Date: Mon, 20 Jun 2005 23:37:45 +0200
>
>Hi everyone,
>
>I have some questions about measure...
>
>As I understand the DA, it is based on conditionnal probabilities. To
>somehow
>calculate the "chance" on doom soon or doom late. An observer should reason
>as if he is a random observer from the "class" of observer.
>
>The conditionnal probabilities come from the fact, that the observer find
>that
>he is the sixty billions and something observer to be "born". Discover this
>fact, this increase the probability of doom soon. The probability is
>increased because if doom late is the case, the probability to find myself
>in
>a universe where billions of billions of observer are present is greater
>but
>I know that I'm the sixty billions and something observer.

I always thought the DA was understood in terms of absolute probability, not
conditional probability. Conditional probability is supposed to tell you,
given your current observer-moment, what the probability of various possible
"next" experiences is for you; absolute probability is supposed to give the
probability of experiencing one observer-moment vs. another *now*. The DA is
based on assuming my current observer-moment is randomly sampled from the
set of all observer-moments (possibly weighted by their absolute
probability, although some people reason as if each observer-moment is
equally likely for the purposes of the random-sampling assumption), and
noting that if civilization were to be very long-lasting, it'd be unlikely
to randomly choose an observer-moment of a person so close to the beginning
of civilization.

Jesse
Received on Mon Jun 20 2005 - 19:43:27 PDT