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Uncommon Priors Require Origin Disputes


In standard belief models, priors are always common knowledge. This prevents such models from representing agents’ probabilistic beliefs about the origins of their priors. By embedding standard models in a larger standard model, however, pre-priors can describe such beliefs. When an agent’s prior and pre-prior are mutually consistent, he must believe that his prior would only have been different in situations where relevant event chances were different, but that variations in other agents’ priors are otherwise completely unrelated to which events are how likely. Due to this, Bayesians who agree enough about the origins of their priors must have the same priors.

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  • Aumann R.J. (1998), Common priors: a reply to Gul. Econometrica 66(4): 929–938

    Article  Google Scholar 

  • Gul F. (1998), A comment on Aumann’s Bayesian view. Econometrica 66(4): 923–927

    Article  Google Scholar 

  • Morris S. (1995), The common prior assumption in economic theory. Economics and Philosophy 11, 227–253

    Article  Google Scholar 

  • Olson J.M., Vernon P.A., Harris J.A., Jang K. (2001), The heritability of attitudes: a study of twins. Journal of Personality and Social Psychology 80(6): 845–860

    Article  Google Scholar 

  • Talbott W. (1990), The Reliability of the Cognitive Mechanism: A Mechanist Account of Empirical Justification. Garland Publishing, New York

    Google Scholar 

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Correspondence to Robin Hanson.

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Hanson, R. Uncommon Priors Require Origin Disputes. Theor Decis 61, 319–328 (2006).

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  • origin
  • common prior
  • disagree
  • Bayesian