Full Idea
Even if the causal theory of reference proper does not presuppose essentialism, it does presuppose essentialism if it is to be an account of reference to modally extended entities.
Gist of Idea
Causal reference presupposes essentialism if it refers to modally extended entities
Source
Alan Sidelle (Necessity, Essence and Individuation [1989], Ch.6)
Book Reference
Sidelle,Alan: 'Necessity, Essence and Individuation' [Cornell 1989], p.190