The authors study preferences over Savage acts that map states to opportunity sets and satisfy the Savage axioms. Preferences over opportunity sets may exhibit a preference for flexibility due to an implicit uncertainty about future preferences reflecting anticipated unforeseen contingencies....

It is shown that well-behaved preference orderings may exhibit the Ellsberg paradox on the set of unambiguous events as defined by Epstein and Zhang (2001). Moreover, since such counterexamples can be constructed even when the set of unambiguous events is rich, EZ’s main representation result...

Coherent imprecise probabilistic beliefs are modelled as incomplete comparative likelihood relations admitting a multiple-prior representation. Under a structural assumption of Equidivisibility, we provide an axiomatization of such relations and show uniqueness of the representation. In the...

While the meaningfulness of the common prior assumption (CPA) under incomplete information has been established recently by various authors, its epistemic rationale has not yet been adequately clarified. To do so, we provide a characterization of the CPA in terms of a new condition called...

A decision-maker is utility-sophisticated if he ranks acts according to their expected utility whenever such comparisons are meaningful. We characterize utility sophistication in cases in which probabilistic beliefs are not too imprecise, and show that in these cases utility-sophisticated...

Two agents are like-minded when their beliefs are equal once conditioned on knowledge of both of their types. Assuming the existence of an outside observer that is commonly known to be likeminded and uninformative about the insiders, we derive the existence of a common prior among the insiders,...