If a decision maker, in a world of uncertainty à la Anscombe and Aumann (1963), can choose acts according to some objective probability distribution (by throwing dice for instance) from any given set of acts, then there is no set of acts that allows an experimenter to test more than the Axiom...

A decision maker (DM) is asked to make choices from a set of acts, which entail both risk and uncertainty in the sense of knight (1921). Extending Raiffa's (1961) argument I show that, provided the DM can choose acts objectively randomly (by flipping her own fair coin, for instance), provided...

We design and implement lab experiments, as close as possible to the Ellsberg two-color urn experiment, to evaluate the positive and normative appeal of behavior arising from models of ambiguity-averse preferences. We report three main empirical findings: First, these preference models do not...

Suppose a decision maker (DM), in the language of Anscombe and Aumann (1963), has preferences over acts (horse-race lotteries) that satisfy the von Neumann and Morgenstern (1944) axioms for objective lotteries (constant acts) and Anscombe and Aumann's (1963) Axioms of Reversal of Order and...