, Volume 52, Issue 1, pp 93–108 | Cite as

Observer-Relative Chances In Anthropic Reasoning?

  • Nick Bostrom


John Leslie presents a thought experiment to show that chances are sometimes observer-relative in a paradoxical way. The pivotal assumption in his argument – a version of the weak anthropic principle – is the same as the one used to get the disturbing Doomsday argument off the ground. I show that Leslie's thought experiment trades on the sense/reference ambiguity and is fallacious. I then describe a related case where chances are observer-relative in an interesting way. But not in a paradoxical way. The result can be generalized: At least for a very wide range of cases, the weak anthropic principle does not giverise to paradoxical observer-relative chances. This finding could be taken to give new indirect support to the doomsday argument.


Thought Experiment Related Case Indirect Support Anthropic Principle Experiment Trade 
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Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Nick Bostrom
    • 1
  1. 1.Department of Philosophy Logic and Scientific MethodLondon School of EconomicsLondonU.K.

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