Abstract.The starting point of deontic logic is the distinction between non‐normative necessity and normative necessity. The first part of the paper shows that the distinction between normative necessity and non‐normative necessity occurs already in Aristotle's Orgunon. The second part of the paper makes a further distinction within normative deon itself: The distinction between deontic deon and anankastic deon. Anankastic deon behaves differently from deontic deon in a very important respect: Deontic indifference has no anankastic counterpart.

Abstract.The paper offers a critical survey of two main sorts of problems hindering the possibility of conceiving deontic logic as a suitable account of the logical behaviour of (sentences expressing) legal norms. The notion of “legal norm” is viewed as the main source of the first sort of problems: (a) the typological variety of legal norms requires an account both of the differing logical behaviour of (sentences expressing) differing legal norms, and of the relations which might hold amon them; (b) (...) the ontologic, semantic, and epistemic features of legal norms shed doubt on the very attempt to figure out a logical analysis of (sentences expressing) legal norms. The notion of “systemic legal validity” is viewed as the main source of the second sort of problems: Deontic logic does not provide suitable logical tools to account for legal phenomena like enactment, derogation, and conflicts between legal norms which rely on systemic legal validity. (shrink)