Re: Holodeck guy tries to prove 'Bruno theory'

From: Saibal Mitra <>
Date: Tue, 16 Apr 2002 11:24:19 +0200

----- Original Message -----
From: Brian Scurfield <>
To: <>
Sent: Tuesday, April 16, 2002 6:47 AM
Subject: RE: Holodeck guy tries to prove 'Bruno theory'

> In this paper Olum defends the self-indicating assumption which says that
> given the fact you exist you should favour hypotheses according to which
> many observers exist over hypotheses according to which few observers
> He sees the following possible problem:
> "However, one should at least give some consideration to the idea that a
> theory which involves a very large number is less likely to be correct
> one which does not. For example, suppose I have a crazy theory that each
> planet has 10^10^100 copies of itself on "other planes". Suppose that I
> cranks often do) believe this theory in spite of the fact that every
> reputable scientist thinks it is garbage. I could argue that my theory is
> very likely to be correct, because the chance that every reputable
> is independently wrong is clearly more than 1 in 10^10^100. To avoid this
> conclusion, one must say that the a priori chance that my theory was right
> was less that 1 in 10^10^100. It seems hard to have such fantastic
> confidence that a theory is wrong, but if we don't allow that we will be
> prey to the argument above." (p. 15)
> A case of having your cake and eating it too?

Maybe, but the idea that any theory with such large numbers must be given
low a priory probability also follows from independent reasoning. E.g. a
natural measurure on the set of all possible universes would show this
behaviour if it is consistent with Ocham's Razor.

Received on Tue Apr 16 2002 - 02:25:53 PDT

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