Inspired by legal reasoning, this paper presents a formal framework for assessing conflicting arguments. Its use is illustrated with applications to realistic legal examples, and the potential for implementation is discussed. The framework has the form of a logical system for defeasible argumentation. Its language, which is of a logic-programming-like nature, has both weak and explicit negation, and conflicts between arguments are decided with the help of priorities on the rules. An important feature of the system is that these priorities (...) are not fixed, but are themselves defeasibly derived as conclusions within the system. Thus debates on the choice between conflicting arguments can also be modelled.The proof theory of the system is stated in dialectical style, where a proof takes the form of a dialogue between a proponent and an opponent of an argument. An argument is shown to be justified if the proponent can make the opponent run out of moves in whatever way the opponent attacks. Despite this dialectical form, the system reflects a declarative, or relational approach to modelling legal argument. A basic assumption of this paper is that this approach complements two other lines of research in AI and Law, investigations of precedent-based reasoning and the development of procedural, or dialectical models of legal argument. (shrink)

Dialogues and dialectics have come to playan important role in the field of ArtificialIntelligence and Law. This paper describes thelegal-theoretical and logical background of this role,and discusses the different services into whichdialogues are put. These services include:characterising logical operators, modelling thedefeasibility of legal reasoning, providing the basisfor legal justification and identifying legal issues,and establishing the law in concrete cases. Specialattention is given to the requirements oflaw-establishing dialogues.

In this paper, the author describes a dialogical approach tolegal argumentation from the perspective of argumentationtheory. In a pragma-dialectical approach of legalargumentation, the argumentation is considered to be part of acritical discussion aimed at the rational resolution of thedispute. The author describes how a pragma-dialecticalanalysis and evaluation of legal argumentation can be carriedout.

ABSTRACT Inspired by legal reasoning, this paper presents a semantics and proof theory of a system for defeasible argumentation. Arguments are expressed in a logic-programming language with both weak and strong negation, conflicts between arguments are decided with the help of priorities on the rules. An important feature of the system is that these priorities are not fixed, but are themselves defeasibly derived as conclusions within the system. Thus debates on the choice between conflicting arguments can also be modelled. The (...) semantics of the system is given with a fixpoint definition, while its proof theory is stated in dialectical style, where a proof takes the form of a dialogue between a proponent and an opponent of an argument: an argument is shown to be justified if the proponent can make the opponent run out of moves in whatever way the opponent attacks. (shrink)

The paper outlines ongoing research on logic-based tools for the analysis and representation of legal contracts, of the kind frequently encountered in large-scale engineering projects and complex, long-term trading agreements. We consider both contract formation and contract performance, in each case identifying the representational issues and the prospects for providing automated support tools.

Mencius, the second sage of Confucianism after Confucius, is well known for his subtle argumentative skills. Mencius did not develop his own argumentation theory, but argumentation practices, including his political argumentation, have enormously inspired later scholars in China to develop argumentation theories. In this paper, we try to reconstruct Mencius’s political argumentation from perspectives of both strategic maneuvering developed by van Eemeren et al. in argumentation theory and truth-functional logic in formal logic. The aim is to manifest the Dao, a (...) rational balance among logical, dialectical and rhetorical dimensions in Mencius’s political argumentation. The results indicate that Mencius’s political argumentation is not only logically justified but also shown to have maneuvered strategically between reasonableness and effectiveness, and that human beings have a common ground of formal and substantial logos, which makes it possible for people from different cultural groups to communicate rationally. (shrink)

Becker argued Confucianism lacked of argumentation, dialogue and debate. However, Becker is wrong. First, the purpose of philosophical argumentation is to justify an arguer’s philosophical standpoints. Second, both Confucius’ Analects and Mencius’ Mencius were written in forms of dialogues. Third, the content of each book is the recorded utterance and the purpose of dialogue is to persuade its audience. Finally, after Confucius, Confucians’ works have either argued for those unjustified standpoints or re-argued about some justified viewpoints in the Analects.

The notion of validity fulfils a crucial role in legal theory. In the emerging Web 3.0, Semantic Web languages, legal ontologies, and normative multi-agent systems are designed to cover new regulatory needs. Conceptual models for complex regulatory systems shape the characteristic features of rules, norms, and principles in different ways. This article outlines one of such multilayered governance models, designed for the CAPER platform, and offers a definition of Semantic Web Regulatory Models . It distinguishes between normative-SWRM and institutional-SWRM. It (...) also compares existing principles in privacy by design, linked open data , legal information institutes , and online dispute resolution . The article concludes by proposing the notion of Relational Law to summarize the ethical dimension of SWRM. Ethics are the only regulatory way to constitute a global space, out of the jurisdictional public domain set by national, international, or transnational law, and opposed to the private one. (shrink)

In the law, it is generally acknowledged that there are intuitive differences between reasoning with rules and reasoning with principles. For instance, a rule seems to lead directly to its conclusion if its condition is satisfied, while a principle seems to lead merely to a reason for its conclusion. However, the implications of these intuitive differences for the logical status of rules and principles remain controversial.A radical opinion has been put forward by Dworkin (1978). The intuitive differences led him to (...) argue for a strict logical distinction between rules and principles. Ever since, there has been a controversy whether the intuitive differences between rules and principles require a strict logical distinction between the two. For instance, Soeteman (1991) disagrees with Dworkin's opinion, and argues that rules and principles cannot be strictly distinguished, and do not have a different logical structure. (shrink)