Class actions have penetrated every sector of American commerce. Significant resources routinely are invested in resisting class certification because of the adverse economic and business management consequences that can follow from classwide relief. In those circumstances when a class is...

We confront two common objections to Harsanyi's impartial observer theorem; one to do with 'fairness', and the other to do with different individuals' having different attitudes toward risk. Both these objections can be accommodated if we drop the reduction axiom; in particular, if we...

The concept of a non-extreme-outcome-additive capacity (neo-additive capacity ) is introduced. Neo-additive capacities model optimistic and pessimistic attitudes towards uncertainty as observed in many experimental studies. Moreover, neo-additive capacities can be applied easily in economic...

This paper shows that, for CEU preferences, the axioms consquentialism, state independence and conditional certainty equivalent consistency under updating characterise a family of capacities, called Genralised Neo-Additive Capacities (GNAC). This family contains as special cases among others...

This paper studies how updating affects ambiguity-attitude. In particular we focus on the generalized Bayesian update of the Jaffray-Phillipe sub-class of Choquet Expected Utility preferences. We find conditions for ambiguity-attitude to be the same before and after updating. A necessary and...