Ali Farjami

University of Luxembourg

Abstract. The so-called modal logic and norm-based paradigms in deontic logic investigate the logical relations among normative concepts such as obligation, permission, and prohibition. The talk unifies these two paradigms by introducing an algebraic framework, called discursive input/output logic. In this framework, deontic modals are evaluated with reference both to a set of possible worlds and a set of norms. The distinctive feature of the new framework is the non-adjunctive definition of input/output operations. This brings us the advantage of modeling discursive reasoning.