 A common starting point for many formal semantic treatments of questions is the idea that “questions set up a choice-situation between a set of propositions, namely those propositions that count as answers to it” (Hamblin 1973, 48). One way to implement this idea is to take a question to denote, in a world \(w\), the set of propositions that correspond to a possible answer to the question (Hamblin 1973). Another way to implement the same idea is to let a question denote, in a world \(w\), the set of propositions that correspond to its true answers in \(w\) (Karttunen 1977). In both systems, the meaning of a question is a function from worlds to sets of propositions. In Hamblin’s system, this function maps every possible world to the same set of propositions, corresponding to the set of all possible answers; in Karttunen’s system, every world is mapped to a subset of all possible answers, namely those that are true in the given world. As acknowledged by Karttunen (1977, 10), the difference is inessential. In both cases, the meaning of a question is fully determined by—and could be identified with—the set of all propositions that correspond to a possible answer.