Minimal Deontic Logics
Johan van Benthem

Abstract:
Free choice permission to Q may be modelled as an inverse universal modality saying that all Q-worlds are deontically accessible (or `acceptable'). We axiomatize the modal validities of the resulting somewhat unusual deontic logic, where permission is no longer the usual negation dual of obligation, and prove decidability of the system.

Note:
The system of this paper has been rediscovered several times in recent years, both in deontic logic of actions and in logical studies of game-theoretic rationality as endorsing a logic of `best action'. It seems useful to make the original text available on-line, since it is hard to access otherwise.