Le groupe "Décision, rationalité et interaction" accueille Richard BRADLEY (London School of Economics) : Ellsberg's Paradox and the Value of Chance.
In this talk I will explore two ideas. First I will consider whether the typical pattern of choices exhibited by agents facing Ellsberg's problem can be rationalised by the hypothesis that they are risk averse with respect to the chances of winning money, a possibility that arises from a natural reframing of the problem they face. Secondly, I will explore the consequences of the more general hypothesis that chances matter, not just instrumentally in virtue of the outcomes with which they are associated, but also intrinsically. In particular I will consider the possibility that the hypothesis allows for a broadly Welfarist explanation for the widely observed fact that we prefer to distribute an indivisible good between equally deserving individuals by using a lottery to determine who gets it (over simply giving it to one of them)