DEONTIC LOGIC
Logics of obligation, permission, and prohibition, in which the modal operators carry a normative rather than an alethic reading. The systems formalize what ought to be, what is allowed, and what is forbidden, and confront the paradoxes that arise when norms conflict or are violated.
Entries are organized from the standard system outward. Standard Deontic Logic (the normal system KD) is the base; dyadic and conditional-obligation systems handle norms relative to circumstances; contrary-to-duty structures and input-output logic address violation and detachment. Agency-based approaches (STIT, deontic action logic, action logic) locate obligation in what agents see to, rather than in bare propositions.