Full Idea
Criteria for identity across times have proven hard to give. Whatever criteria we lay down, it seems that there are possible situations in which two later objects bear the relevant relation to one earlier object, though only one of them can be identical.
Gist of Idea
Most criteria for identity over time seem to leave two later objects identical to the earlier one
Source
Ross P. Cameron (Intrinsic and Extrinsic Properties [2009], 'Personal')
Book Reference
'Routledge Companion to Metaphysics', ed/tr. Le Poidevin/Simons etc [Routledge 2012], p.267
A Reaction
We only have to think of twins, amoebae that fission, and the Ship of Theseus. We seem to end up inventing a dubious criterion in order to break the tie.