Evidential Incomparability and the Principle of Indifference

The Principle of Indifference (POI) was once regarded as a linchpin of probabilistic reasoning, but has now fallen into disrepute as a result of the so-called problem of multiple of partitions. In ‘Evidential symmetry and mushy credence’ Roger White suggests that we have been too quick to jettison this principle and argues that the problem of multiple partitions rests on a mistake. In this paper I will criticise White’s attempt to revive POI. In so doing, I will argue that what underlies the problem of multiple partitions is a fundamental tension between POI and the very idea of evidential incomparability.