 Counterpart theory is also significant to the topic of identity over time in another way, since it provides the analogy to which the stage theorist (who regards all everyday reference as reference to momentary stages rather than to perdurers) appeals to explain de re temporal predication. Thus, according to the stage theorist, just as “I might have been fat” does not require the existence of a possible world in which an object identical with me is fat, but only the existence of a world in which a (modal) counterpart of me is fat, so “I used to be fat” does not require the existence of a past time at which someone identical with (the present momentary stage which is) me was fat, but only the existence of a past time at which a (temporal) counterpart of me was fat. The problem of identity over time for things of a kind, for stage theorists, is just the problem of characterizing the appropriate temporal counterpart relation for things of that kind.