A Deontic Argumentation Framework Towards Doctrine Reification

A modular rule-based argumentation system is proposed to represent and reason upon conditional norms featuring obligations, prohibitions, and (strong or weak) permissions. The approach is based on common constructs in computational models of argument: rule-based arguments, argumentation graphs, argument labelling semantics and statement labelling semantics. Deontic reasoning patterns are captured with defeasible rule schemata to the greatest extent, towards the reification of doctrinal pieces. We show then that bivalent statement labellings can fall short to address normative completeness, and for this reason, we propose to use trivalent labelling semantics. Given an argumentation graph, deontic statuses can be computed efficiently. The system is illustrated with a scenario featuring a violation and a contrary-to-duty obligation.