Chateauneuf, AlainEichberger, JürgenGrant, Simon2022-12-020022-0531http://hdl.handle.net/1885/281498We develop the simplest generalization of subjective expected utility that can accommodate both optimistic and pessimistic attitudes towards uncertainty—Choquet expected utility with non-extreme-outcome-additive (neo-additive) capacities.A neo-additive capacity can be expressed as the convex combination of a probability and a special capacity, we refer to as a Hurwicz capacity, that only distinguishes between whether an event is impossible, possible or certain. We show that neo-additive capacities can be readily applied in economic problems, and we provide an axiomatization in a framework of purely subjective uncertainty.application/pdfen-AU© 2007 The authorsComonotonic preferencesOptimismSubjective mixturesChoquet expected utilityPessimism200710.1016/j.jet.2007.01.0172021-11-28