Full Idea
Talk of possible worlds is a graphic way of waging the essentialist philosophy, but it is only that; it is not an explication. Essence is needed to identify an object from one possible world to another.
Gist of Idea
Possible worlds are a way to dramatise essentialism, and yet they presuppose essentialism
Source
Willard Quine (Intensions Revisited [1977], p.118)
Book Reference
Quine,Willard: 'Theories and Things' [Harvard 1981], p.118
A Reaction
He makes the proposal sound circular, but I take a commitment to essences to be prior to talk of possible worlds. Possible worlds are a tool for clarifying modalities, not for clarifying essential identities.