# RE: Measure, Doomsday argument

```From: Quentin Anciaux <[EMAIL PROTECTED]>
To: everything-list@eskimo.com
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

```