Troubles for Bayesian formal epistemology

Terry Horgan

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20 Scopus citations


I raise skeptical doubts about the prospects of Bayesian formal epistemology for providing an adequate general normative model of epistemic rationality. The notion of credence, I argue, embodies a very dubious psychological myth, viz., that for virtually any proposition p that one can entertain and understand, one has some quantitatively precise, 0-to-1 ratio-scale, doxastic attitude toward p. The concept of credence faces further serious problems as well-different ones depending on whether credence 1 is construed as full belief (the limit case of so-called partial belief) or instead is construed as absolute certainty. I argue that the notion of an "ideal Bayesian reasoner" cannot serve as a normative ideal that actual human agents should seek to emulate as closely as they can, because different such reasoners who all have the same evidence as oneself-no single one them being uniquely psychologically most similar to oneself-will differ from one another in their credences (e.g., because they commence from different prior credences). I argue that epistemic probability, properly understood, is quantitative degree of evidential support relative to one's evidence, and that principled epistemic probabilities arise only under quite special evidential circumstances-which means that epistemic probability is ill suited to figure centrally within general norms of human epistemic rationality.

Original languageEnglish (US)
Pages (from-to)233-255
Number of pages23
JournalRes Philosophica
Issue number2
StatePublished - Apr 2017

ASJC Scopus subject areas

  • Philosophy


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