A metalogic formalization of legal argumentation as game trees with defeasible reasoning

Abstract

We outline an approach to logical analysis and formalization of legal argumentation and dispute as game trees, wellknown in AI, using metalogic programming. The argument/counterargument dialectic is facilitated through defeasible reasoning, and the applied principles are sought demonstrated by unravelling of a legal case within statutory law.

An Asymmetric Protocol for Argumentation Games in Defeasible Logic

“…In this paper we augment the model of dialogue games in defeasible logic of [24]. The work is based on ALIS [21], and we are inspired by [13] as we have separated the knowledge of the players into (1) private knowledge and (2) public knowledge. The common public knowledge forms the common set of arguments, which is a theory in defeasible logic.…”

“…Modelling argumentation games in defeasible logic has been addressed by [13,12,14]. [14], in contrast to our work, focuses on persuasion dialogues in a cooperative setting.…”

“…Section 3), while ignoring recent development in extensions of defeasible logic with modal and epistemic operators for representing the cognitive states of agents [9,10]. [13] provides an extension of defeasible logic to include the step of the dialogue in a way very similar to what we have presented in the paper. A main difference is that the resulting mechanism just defines a metaprogram for an alternative computational algorithm for ambiguity propagating defeasible logic while the logic presented here is ambiguity blocking.…”

A rule-sceptic characterization of acceptable legal arguments

“…Prior to the analysis carried out in the argumentation framework [4], we constructed a legally acceptable and meaningful formal theory for a legal case on claiming ownership of land through prescriptive rights. This is accomplished by the formalization Demo of provability given the legislation Code and the speech acts and evidence put forward in the pleas of the parties Party1 and Party2 .…”

“…To pursue analysis as to whether the key claim or its denial hold, we use the game tree explorer of our framework [4]. ∴ The game is won by Party1.…”