Objective rationality foundations for (dynamic) α-MEU

• 成果类型: Article
• 署名作者: Frick, Mira; Iijima, Ryota; Le Yaouanq, Yves
• 署名单位: Yale University; Institut Polytechnique de Paris; ENSAE Paris; Ecole Polytechnique; University of Munich; Center for Economic & Policy Research (CEPR)
• 刊物名称: JOURNAL OF ECONOMIC THEORY
• ISSN/ISSBN: 0022-0531
• DOI: 10.1016/j.jet.2021.105394
• 发表日期: 2022
• 关键词: Ambiguity; alpha-MEU; objective rationality; updating

摘要

We show how incorporating Gilboa et al.'s (2010) notion of objective rationality into the a-MEU model of choice under ambiguity can overcome several challenges faced by the baseline model without objective rationality. The decision-maker (DM) has a subjectively rationalpreference greater than or similar to(Lambda)which captures the complete ranking over acts the DM expresses when forced to make a choice; in addition, we endow the DM with a (possibly incomplete) objectively rationalpreference greater than or similar to*, which captures the rankings the DM deems uncontroversial. Under the objectively founded alpha-MEU model, greater than or similar to(Lambda) has an a-MEU representation and greater than or similar to* has a unanimity representation a la Bewley (2002), where both representations feature the same utility index and set of beliefs. While the axiomatic foundations of the baseline a-MEU model are still not fully understood, we provide a simple characterization of its objectively founded counterpart. Moreover, in contrast with the baseline model, the model parameters are uniquely identified. Finally, we provide axiomatic foundations for prior-by-prior Bayesian updating of the objectively founded a-MEU model, while we show that, for the baseline model, standard updating rules can be ill-defined.