Present and Future of Formal Argumentation (Dagstuhl Perspectives Workshop 15362)

in Dagstuhl Manifestos (2018), 7(1), 69--95

Formal Argumentation is emerging as a key reasoning paradigm building bridges among knowledge representation and reasoning in artificial intelligence, informal argumentation in philosophy and linguistics ... [more ▼]

Formal Argumentation is emerging as a key reasoning paradigm building bridges among knowledge representation and reasoning in artificial intelligence, informal argumentation in philosophy and linguistics, legal and ethical argumentation, mathematical and logical reasoning, and graph-theoretic reasoning. It aims to capture diverse kinds of reasoning and dialogue activities in the presence of uncertainty and conflicting information in a formal and intuitive way, with potential applications ranging from argumentation mining, via LegalTech and machine ethics, to therapy in clinical psychology. The turning point for the modern stage of formal argumentation theory, much similar to the introduction of possible worlds semantics for the theory of modality, is the framework and language of Dung’s abstract argumentation theory introduced in 1995. This means that nothing could remain the same as before 1995 — it should be a focal point of reference for any study of argumentation, even if it is critical about it. Now, in modal logic, the introduction of the possible worlds semantics has led to a complete paradigm shift, both in tools and new subjects of studies. This is still not fully true for what is going on in argumentation theory. The Dagstuhl workshop led to the first volume of a handbook series in formal argumentation, reflecting the new stage of the development of argumentation theory. [less ▲]

Prioritized Norms in Formal Argumentation

in Journal of Logic and Computation (2017), abs/1709.08034

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 ... [more ▼]

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 implicit conflicts between arguments. [less ▲]

Handling Norms in Multi-Agent System by Means of Formal Argumentation

in IfCoLog Journal of Logics and Their Applications (2017)

Formal argumentation is used to enrich and analyse normative multi-agent systems in various ways. In this chapter, we discuss three examples from the literature of handling norms by means of formal ... [more ▼]

Formal argumentation is used to enrich and analyse normative multi-agent systems in various ways. In this chapter, we discuss three examples from the literature of handling norms by means of formal argumentation. First, we discuss how existing ways to resolve conflicts among norms using priorities can be represented in formal argumentation, by showing that the so-called Greedy and Reduction approaches can be represented using the weakest and the last link principles respectively. Based on such representation results, formal argumentation can be used to explain the detachment of obligations and permissions from hierarchical normative systems in a new way. Second, we discuss how formal argumentation can be used as a general theory for developing new approaches for normative reasoning, using a dynamic ASPIC-based legal argumentation theory. We show how existing logics of normative systems can be used to analyse such new argumentation systems. Third, we show how argumentation can be used to reason about other challenges in the area of normative multiagent systems as well, by discussing a model for arguing about legal interpretation. In particular, we show how fuzzy logic combined with formal argumentation can be used to reason about the adoption of graded categories and thus address the problem of open texture in normative interpretation. Our aim to discuss these three examples is to inspire new applications of formal argumentation to the challenges of normative reasoning in multiagent systems. [less ▲]