A Stage-Theoretical Account of Diachronic Identity

Abstract

Abstract Diachronic identity is understood as an identity holding between something existing at one time and something existing at another time. On the stage view, however, ordinary objects are instantaneous stages that do not exist at other times so diachronic identity is, at best, problematic. On account proposed here a name does not, as Sider and others suggest, denote a stage concurrent with its utterance. Rather, at any time, t, a name of an ordinary object designates a stage-at-t as its primary referent and refers indeterminately over it and all and only those stages counterpart-related to it—its reference class at t. At any time, t, a at t1 is the same object as b at t2 iff for every stage x counterpart-related to a’s stage-at t and every stage y counterpart-related to b’s stage-at-t, x=y. Diachronic identity statements, therefore, assert strict identities—between concurrent stages. Ordinarily names select the same reference classes at every time so, in ordinary cases, identity statements are not ‘occasional’. In fission cases names select different reference classes at different times. Where a becomes b and c, at any pre-fission time ‘a’, ‘b’, and ‘c’ have same the primary referent and so select the same reference class—therefore, before fission b is the same object as c. At any post-fission time ‘b’ and ‘c’ select different reference classes—so after fission b is not the same object as c. Identity is not occasional but, in extraordinary cases, identity statements are—because reference is.