Abstract

The paper offers an explanation of the intuitive appeal of Saul Kripke's necessity of origin thesis, exhibiting it as the consequence of a temporally asymmetrical 'branching model' of possibilities which, in turn, rests on two plausible principles concerning possibility, time, and identity. Unlike some other accounts, my explanation dissociates the necessity of origin thesis from a commitment to individual essences or other sufficient conditions for identity across possible worlds. I conclude that although the branching model is not irresistible, its rejection may necessitate the denial of a plausible principle that requires possibilities for actual individuals to be 'anchored' to their actual characteristics