 Among conditional questions we can distinguish those in which the addressee is presumed to know whether the antecedent is true, and those in which he is not. In the latter case, the addressee is being asked to suppose that the antecedent is true, and give his opinion about the consequent: “If it rains, will the match be cancelled?”. In the former case — “If you have been to London, did you like it?” — he is expected to answer the consequent-question if the antecedent is true. If the antecedent is false, the question lapses: there is no conditional belief for him to express. “Not applicable” as the childless might write on a form which asks “If you have children, how many children do you have?”. You are not being asked how many children you have in the nearest possible world in which you have children. Nor is it permissible to answer “17” on the grounds that “I have children \(\supset\) I have 17 children” is true. Nor are you being asked what you would believe about the consequent if you came to believe that you did have children.