[extropy-chat] Doomsday argument

Robin Hanson rhanson at gmu.edu
Sun Oct 15 23:16:32 UTC 2006

At 11:19 PM 10/13/2006, Lee Corbin wrote:
> > If there are many aliens out there, then the total number of
> > creatures that we could have been in the universe doesn't change much
> > from scenarios where our civilization dies fast or lasts long.   So if
> > you are a random creature among all these creatures,
>I think that this is probably exactly the point at which Russell demurs.
>That's what I've never been able to choke down myself. And I know
>that Eliezer has publically denigrated such a calculus of souls, rightly
>saying that it's bad to think about a sample space (made up, say, of
>all sentient entities) from which you were drawn at random---
>in other words, that a priori, it was equally likely that you could have
>been born in the four centuries before Christ as that you were born
>in the U.S. in the 1960's.  No way!
>You could not have been born anywhere except on Earth and in
>the 20th century at that. You are the result of a baby with certain
>genetic traits being raised in a 20th century type environment. It is
>not possible that you could have been born with twelve tentacles
>living in a methane atmosphere and holding absolute religious
>convictions concerning the Great Squid that preclude all scientific
>or rational thinking.  It simple wouldn't be you.  Therefore as
>Eliezer says, the sample space is bad; and Bostrom and others
>seem to have been thinking that its made of soul-like points in the
>space of all possible outcomes.

Counterfactuals are one of our most powerful intellectual tools.
If we had to swear off using them our thinking would be immensely
impoverished.   They infuse science and ordinary thinking in equal
measures.    Sometimes the language we use to describe
counterfactuals makes it ambiguous which ones we refer to, but
the idea that we can imagine situations other than the one we find
ourselves and ask ourselves what we should believe in such situations
is a powerful way to clarify what we should believe in our real situation.

"What if you didn't know when you were born or what civilization you live
in" is an example of a useful thought-clarifying counterfactual.

Robin Hanson  rhanson at gmu.edu  http://hanson.gmu.edu
Associate Professor of Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030-4444
703-993-2326  FAX: 703-993-2323 

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