ABSTRACT
It is sometimes said that there are two theories of identity across time. First, there is “three-dimensionalism,” according to which persisting objects are extended in the three spatial dimensions and have no other kind of extent and persist by “enduring through time” (whatever exactly that means). Secondly, there is “four-dimensionalism,” according to which persisting objects are extended not only in the three spatial dimensions, but also in a fourth, temporal, dimension, and persist simply by being temporally extended.
