If event e occurs before event c, then any possible world identical to the actual world up to c necessarily includes the occurrence of e.

However, and more importantly in the present context, is that Stalnaker-Lewis’ theory of counterfactuals has difficulties with backtracking counterfactuals and backward causation because if \(c\) occurs later than \(e\), the proposed method of truth evaluation assumes that \(e\) occurs in the relevant possible worlds in which \(c\) does not occur. In general, the assessment of a counterfactual conditional is carried out by assuming that the possible world must be identical with the actual world