Abstract
Regarding the identity of artifacts in time, four positions may be discerned: first, the view reducing the continuing identity of an object to the continuing identity of its parts; second, the more generally accepted position that spatiotemporal continuity under a kind is necessary; third, the claim that while continuity is not a necessary condition, the sameness of parts and the sameness of form are sufficient together; and fourth, the suggestion that continuity of form is a sufficient and non-defeasible condition for reidentifying artifacts. Others such as Scaltsas believe that the different conditions claimed to be sufficient by the views mentioned are, in fact, only criteria of identity applicable in different circumstances, and that no sharply defined hierarchy can be said to hold between them.