Some Alleged Differences between Imperatives and Indicatives
Anybody who studies imperative or deontic logic is bound to be very soon faced with the question of whether the logic or group of logics that he is studying differs radically from ordinary ‘indicative’ or ‘assertoric’ logic, or whether it can be accommodated, after a few relatively simple explanations, within the framework of ordinary logic. It would be foolish to pretend that this question can yet be settled. In this article I am going to maintain a less ambitious thesis: that several of the reasons which various writers have given for alleging differences between imperative and ordinary logic are based on misunderstandings. I shall divide these misunderstandings into two groups. The first can, I think, be removed by a straightforward application of Mr Grice’s recent work on what he calls ‘implicatures’; and the second, by insisting on the distinction, often ignored, between ordinary singular imperatives, on the one hand, and ‘ought’-sentences on the other. This important distinction is obscured by those systems of deontic logic which use the same symbol or operator for both purposes.
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