To do something else

This paper presents two deontic logics following an old idea: normative notions can be de ned in terms of the consequences of performing actions. The two deontic logics are based on two special propositional dynamic logics; they interpret actions as sets of state sequences and have a process modality. The di erence between the two deontic logics is that they contain di erent formalizations of refraining to do an action. Both of the two deontic logics have a propositional constant for marking the bad states. The normative notions are expressed by use of the process modality and this propositional constant.