https://hal-hec.archives-ouvertes.fr/hal-00493170Gilboa, ItzhakItzhakGilboaGREGH - Groupement de Recherche et d'Etudes en Gestion à HEC - HEC Paris - Ecole des Hautes Etudes Commerciales - CNRS - Centre National de la Recherche ScientifiquePostlewaite, AndrewAndrewPostlewaiteSchmeidler, DavidDavidSchmeidlerIs It Always Rational to Satisfy Savage's Axioms?HAL CCSD2009StudiesEconomic theoryProbabilityPhilosophy[SHS.ECO.ECO] Humanities and Social Sciences/Economics and Finance/Economy and decision scienceHaldemann, Antoine2010-06-18 10:42:562022-06-25 10:50:552010-06-18 14:13:41enJournal articles10.1017/S02662671099902411This note argues that, under some circumstances, it is more rational not to behave in accordance with a Bayesian prior than to do so. The starting point is that in the absence of information, choosing a prior is arbitrary. If the prior is to have meaningful implications, it is more rational to admit that one does not have sufficient information to generate a prior than to pretend that one does. This suggests a view of rationality that requires a compromise between internal coherence and justification, similarly to compromises that appear in moral dilemmas. Finally, it is argued that Savage's axioms are more compelling when applied to a naturally given state space than to an analytically constructed one, in the latter case, it may be more rational to violate the axioms than to be Bayesian.