Two approaches to the formalisation of defeasible deontic reasoning (Q1922822)

This paper contrasts two ways of formalizing defeasible deontic reasoning. One is the method of Horty, which develops a special nonmonotonic logic for deontic statements. The other, which the author recommends, adds standard deontic principles to an existing nonmonotonic (non-deontic) logic, such as Reiter's default logic. Both types of system are designed to give a plausible analysis of moral dilemmas and possible conflicts of prima facie obligations. It is odd, then, that the second method accepts commitment to the principle \(\sim (OA \& O \sim A)\), though the author argues that this is acceptable.