Philosophical Studies

, Volume 175, Issue 10, pp 2389–2398 | Cite as

No one can serve two epistemic masters

  • J. Dmitri GallowEmail author


Consider two epistemic experts—for concreteness, let them be two weather forecasters. Suppose that you aren’t certain that they will issue identical forecasts, and you would like to proportion your degrees of belief to theirs in the following way: first, conditional on either’s forecast of rain being x, you’d like your own degree of belief in rain to be x. Secondly, conditional on them issuing different forecasts of rain, you’d like your own degree of belief in rain to be some weighted average of the forecast of each (perhaps with weights determined by their prior reliability). Finally, you’d like your degrees of belief to be given by an orthodox probability measure. Moderate ambitions, all. But you can’t always get what you want.


Expert deference Disagreement Linear averaging 



Thanks to Michael Caie, Daniel Drucker, Harvey Lederman, and an anonymous reviewer for helpful conversations and feedback.


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Copyright information

© Springer Science+Business Media B.V. 2017

Authors and Affiliations

  1. 1.Department of PhilosophyThe University of PittsburghPittsburghUSA

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