 Note first that for all sentences of the form “A or B”, the negation of A is satisfied within the right disjunct. So “Geraldine is a mormon” is satisfied in the right disjunct of (27). And more generally, anything entailed by a combination of propositions in the context and the negation of the left disjunct will be satisfied in the right disjunct. Now, let us consider the clause “she has given up wearing her holy underwear”: we take this to trigger the presupposition that Geraldine has had holy underwear that she wore. This presupposition will be satisfied provided the global context of utterance, combined with the negation of the left disjunct, entails that she has had holy underwear that she wore. And classically this will be the case if and only if the context supports the conditional “if Geraldine is a mormon, then she has had holy underwear that she wore” (which would also be the case if the context supported something stronger). Hence, this conditional is the presupposition Karttunen (1974) predicts for (27).