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Objective and Subjective Rationality in a Multiple Prior Model
Author(s) -
Gilboa Itzhak,
Maccheroni Fabio,
Marinacci Massimo,
Schmeidler David
Publication year - 2010
Publication title -
econometrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 16.7
H-Index - 199
eISSN - 1468-0262
pISSN - 0012-9682
DOI - 10.3982/ecta8223
Subject(s) - rationality , mathematical economics , axiom , subjective expected utility , binary relation , prior probability , context (archaeology) , ecological rationality , expected utility hypothesis , mathematics , set (abstract data type) , representation (politics) , decision theory , computer science , epistemology , discrete mathematics , bayesian probability , statistics , paleontology , biology , programming language , philosophy , geometry , politics , political science , law
A decision maker (DM) is characterized by two binary relations. The first reflects choices that are rational in an “objective” sense: the DM can convince others that she is right in making them. The second relation models choices that are rational in a “subjective” sense: the DM cannot be convinced that she is wrong in making them. In the context of decision under uncertainty, we propose axioms that the two notions of rationality might satisfy. These axioms allow a joint representation by a single set of prior probabilities and a single utility index. It is “objectively rational” to choose f in the presence of g if and only if the expected utility of f is at least as high as that of g given each and every prior in the set. It is “subjectively rational” to choose f rather than g if and only if the minimal expected utility of f (with respect to all priors in the set) is at least as high as that of g . In other words, the objective and subjective rationality relations admit, respectively, a representation à la Bewley (2002) and à la Gilboa and Schmeidler (1989). Our results thus provide a bridge between these two classic models, as well as a novel foundation for the latter.