Since W1 contains p, every conjunct of p in the actual world W is also a conjunct of the BCCF of W1, so no property of p is absent from W1.

If one grants modal Axiom S5 (if it is possible that it is necessary that \(p\), then it is necessary that \(p\)), the critical premise in the argument is the second, and Gale and Pruss proceed to defend it using their weak PSR. They begin with the notion of a Big Conjunctive Fact (BCF), which is the totality of propositions that would be true of any possible world were it actualized. Since all possible worlds would have the same necessary propositions, they are differentiated by their Big Conjunctive Contingent Fact (BCCF), which would contain different contingent propositions. Let \(p\) be t...