Defending the Ramsey Test: What is wrong with Preservation?



janvier 2012, vol. 121, n°481, pp.131-146

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Mots clés : Conditionals, Revisions

In `A Defence of the Ramsey Test', Richard Bradley makes a case for not concluding from the famous impossibility results regarding the Ramsey Test ' the thesis that a rational agent believes a conditional if he would believe the consequent upon learning the anteceden ' that the thesis is false. He lays the blame instead on one of the other premisses in these results, namely the Preservation condition. In this paper, we explore how this condition can be weakened by strengthening the notion of consistency which appears in it. After considering the ffects of such weakenings for Bradley's argument, we propose a refinement of the Preservation condition which does not fall prey to Bradley's argument nor to Gärdenfors's impossibility theorem. We briefly compare it to Bradley's suggested restriction of Preservation