Updating Confidence in Beliefs

42 Pages Posted: 16 May 2019 Last revised: 28 Sep 2019

See all articles by Brian Hill

Brian Hill

HEC Paris - Economics & Decision Sciences; CNRS

Date Written: May 8, 2019


This paper develops a belief update rule under ambiguity, motivated by the maxim: in the face of new information, retain those conditional beliefs in which you are more confident, and relinquish only those in which you have less confidence. We provide a preference-based axiomatisation, drawing on the account of confidence in beliefs developed in Hill (2013). The proposed rule constitutes a general framework of which several existing rules for multiple priors (Full Bayesian, Maximum Likelihood) are special cases, but avoids the problems that these rules have with updating on complete ignorance. Moreover, it can handle surprising and null events, such as crises or reasoning in games, recovering traditional approaches, such as conditional probability systems, as special cases.

Keywords: Belief Update, Ambiguity, Multiple Priors, Confidence, Complete ignorance, Update on Surprising or Null Events

JEL Classification: D81, D83

Suggested Citation

Hill, Brian, Updating Confidence in Beliefs (May 8, 2019). HEC Paris Research Paper No. ECO/SCD-2019-1338, Available at SSRN: https://ssrn.com/abstract=3385116 or http://dx.doi.org/10.2139/ssrn.3385116

Brian Hill (Contact Author)

HEC Paris - Economics & Decision Sciences ( email )


CNRS ( email )

3, rue Michel-Ange
Paris, 75794

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