Prioritized Norms in Formal Argumentation

TL;DR

This paper introduces a novel argumentation-based framework for prioritized normative reasoning, defining three approaches and demonstrating their representation within hierarchical abstract normative systems.

Contribution

It formalizes three prioritized normative reasoning methods—Greedy, Reduction, and Optimization—within an argumentation framework, linking them to existing principles.

Findings

Greedy and Reduction are representable via weakest and last link principles.

Optimization is captured by additional defeat relations.

Framework effectively models prioritized normative reasoning.

Abstract

To resolve conflicts among norms, various nonmonotonic formalisms can be used to perform prioritized normative reasoning. Meanwhile, formal argumentation provides a way to represent nonmonotonic logics. In this paper, we propose a representation of prioritized normative reasoning by argumentation. Using hierarchical abstract normative systems, we define three kinds of prioritized normative reasoning approaches, called Greedy, Reduction, and Optimization. Then, after formulating an argumentation theory for a hierarchical abstract normative system, we show that for a totally ordered hierarchical abstract normative system, Greedy and Reduction can be represented in argumentation by applying the weakest link and the last link principles respectively, and Optimization can be represented by introducing additional defeats capturing the idea that for each argument that contains a norm not belonging to the maximal obeyable set then this argument should be rejected.