Hal wrote:

> Jonathan Colvin writes, regarding the Doomsday argument:
> > There's a simple answer to that one. Presumably, a million 
> years from 
> > now in the Galactic Empire, the Doomsday argument is no longer 
> > controversial, and it will not be a topic for debate. The 
> fact that we 
> > are all debating the Doomsday argument implies we are all 
> part of the 
> > reference class: (people debating the doomsday argument), and we 
> > perforce can not be part of the Galactic Empire.
> Well, I don't want to open up discussion of the DA.  Suffice 
> it to say that good thinkers have spent considerable amounts 
> of time considering it and don't necessarily think that this 
> reply puts it to bed.
> http://www.anthropic-principle.com has an exhaustive discussion.

Since it is coming from Nick B., over-exhaustive :) 
I don't think anybody, Nick included, has yet come up with a convincing way
to define appropriate reference classes. Absent this, the only way to rescue
the DA seems to be a sort of dualism (randomly emplaced souls etc).

> [Regarding measure and size]
> > I find these conclusions counter-intuitive enough to suggest that 
> > deriving measure from a physical fraction of involved reasources is 
> > not the correct way to derive measure. It is not unlike trying to 
> > derive the importance of a book by weighing it.
> Don't be too eager to throw out this concept of measure.  It 
> is fundamental to the Schmidhuber and Tegmark approach to the 
> multiverse.
> It allows deriving why induction works as well as Occam's razor.
> It explains why the universe is lawful and has a simple description.
> It allows us in principle to calculate how likely we are to 
> be in The Matrix or some such simulation vs a basement-level 
> universe.  It is quite an amazing quantity of results from 
> such a simple assumption.
> I don't think you will find anything else like it in philosophy.
> As far as the specific issue of measure and size, suppose you 
> agree that making copies of a structure increases its 
> measure, but you object to the idea that scaling up its size 
> would do so.  Years ago I came up with a thought experiment 
> that adopted the position you have, that size doesn't matter. 
>  (That's what my wife kept telling me, after all...) From 
> that I proved that copies didn't matter either, which wasn't 
> too appealing.  Today I would say that my premise was wrong.  
> Size matters.

Isn't there a counter argument, though? Imagine a Universe of size X, and
that observers have size Y<X. As Y increases towards X, the number of
possible observers in the Universe decreases, until at the limit Y=X a
universe can contain only one observer. Conversely, the smaller the Y, the
more observers the universe can contain (and presumably the larger the
measure). On this argument, *decreasing* our size should increase our
measure (in the same way that smaller universes have greater measure).

Jonathan Colvin

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