COMMA 2022

Abstract. Normative reasoning is inherently defeasible. Formal argumentation has proven to be a unifying framework for representing nonmonotonic logics. In this work, we provide an argumentative characterization of a large class of Input/Output logics, a prominent defeasible formalism for normative reasoning. In many normative reasoning contexts, one is not merely interested in knowing whether a specific obligation holds, but also in why it holds despite other norms to the contrary. We propose sequent-style argumentation systems called Deontic Argument Calculi (\(\calc\)), which serve transparency and bring meta-reasoning about the inapplicability of norms to the object language level. We prove soundness and completeness between $\calc$-instantiated argumentation frameworks and constrained Input/Output logics. We illustrate our approach in view of two deontic paradoxes.

Explainable artificial intelligence (XAI) has gained increasing interest in recent years in the argumentation community. In this paper we consider this topic in the context of logic-based argumentation, showing that the latter is a particularly promising paradigm for facilitating explainable AI. In particular, we provide two representations of abductive reasoning by sequent-based argumentation frameworks and show that such frameworks successfully cope with related challenges, such as the handling of synonyms, justifications, and logical equivalences.