Abstract

This paper presents an argument to the effect that the relation of exact similarity with respect to properties that are supervenient cannot be transitive. The point of departure is that, while a difference in respect of supervenient properties entails a difference in respect of subvenient properties, exact similiarity in respect of supervenient properties is compatible with differences in respect of subvenient properties. It is logically possible that two such sets of differences that each individually is insufficient for a difference as regards the supervenient property together are sufficient for such a supervenient difference. This possibility claim is incompatible with the necessity claim entailed by the transitivity of exact similarity. Several objections to this argument are then considered.