This chapter scrutinises the framework within which Kant decides to conduct his argument against Constant. Constant argues that the would-be murderer has forfeited his right to be told the truth. Kant argues that the duty to be truthful does not depend on that kind of right; that Constant fails to distinguish between truth and truthfulness with sufficient care; and that one should distinguish the question of whether lying is permissible (licence to lie) in emergencies from the question of whether lying is ever morally required (obligation to lie). In the 1797 essay, Kant addresses the second question through the first. If there is never a licence to lie, there can be no obligation to do so.