A logical calculus created by adding operators ‘Op’ (it ought to be the case that p) and ‘Pp’ (it is permissible that p) to a basic system such as the propositional calculus, together with rules of inference for them. A deontic logic will study inferences between these forms, telling for instance whether Op & p → q yield Oq, or whether Op → ¬O¬p. Principles such as these have proved controversial and there is no one ‘classical’ system of deontic logic. See also gentle murder, paradox of.
Subjects: Philosophy — Psychology.