Formalising Oughts and Practical Knowledge without Resorting to Action Types

摘要

We show how the logical modelling of puzzles concerning epistemic oughts, such as those put forward by Horty & Pacuit, are solved without introducing action types. We accomplish this within stit logic ([2], [6]), by lifting a deontic ordering over histories to the level of actions that an agent can knowingly perform. Through the relation of 'can' and 'practical knowledge', we arrive at objective and subjective axiomatizable versions of the ought-to-do modality.