Deontic Logic in Computer Science

Throughout its history, deontic logic had to face the question whether it is a logic of descriptions or a logic of prescriptions, namely of imperatives. The paper describes how the idea that there is a ‘logic of imperatives’ first came about, what proposals there have been to explain it and what problems it has had difficulties to solve. The paper argues that the idea of a logic of imperatives rests on a mistaken parallelism between imperative and indicative language and that there is, as a matter of fact, no such logic. However, we can argue about what ought to be done or need not be done according to given imperatives, and appeal to existing imperatives to motivate new ones. Descriptively interpreted deontic logic suffices to explain the reasoning involved.