Debates and Decisions: On a Rationale of Argumentation Rules

2008

We present a game-theoretic model of debate and a laboratory experiment that explore how strategic incentives to make potentially persuasive arguments vary across different informational and institutional contexts. In our model, a key feature of the informational environment is the extent to which members of a debate audience are able to extract informational content from exposure to an argument that they find unconvincing. Our theoretical results show that when the informational content of unconvincing arguments is relatively high, speakers are discouraged from arguing irrespective of the distinct institutional rules of debate that we consider. By contrast, when the informational content of unconvincing arguments is relatively low, debate rules matter: speakers may be lead towards maximally or minimally informative debate, depending on the debate rule. In a laboratory experiment, we vary the informational and institutional settings for debate across four distinct treatments, and ob...

Proceedings of the Sixth Workshop on Computational Models for Natural Argument, 2006

Abstract. While researchers have looked at many aspects of argumentation, an area often neglected is that of argumentation strategies. That is, given multiple possible arguments that an agent can put forth, which should be selected in what circumstances. In this paper, we propose a heuristic that implements one such strategy. The heuristic assigns a utility cost to revealing information, as well as a utility to winning, drawing and losing an argument. An agent participating in a dialogue then attempts to maximise its utility. After informally ...

Social Choice and Welfare, 2006

An axiomatic modeling approach to multi-issue debates is proposed. A debate is viewed as a decision procedure consisting of two stages: (1) an "argumentation rule" determines what arguments are admissible for each party, given the "raw data", depending on the issue or set of issues under discussion; (2) a "persuasion rule" determines the strength of the admissible arguments and selects the winning party. Persuasion rules are characterized for various alternative specifications of the argumentation rule. These characterizations capture rhetorical effects that we sometimes encounter in real-life multi-issue debates.

In this paper, the term 'debate' refers to a situation in which two parties disagree over some issue and each of them tries to persuade a third party, the listener, to adopt his position by raising arguments in his favor. We are interested in the logic behind the relative strength of the arguments and counterarguments; we therefore limit our discussion to debates in which one side is asked to argue first, with the other party having the right to respond before the listener makes up his mind.

Journal of Applied Logic, 2016

This article demonstrates that typical restrictions which are imposed in dialogical logic in order to recover first-order logical consequence from a fragment of natural language argumentation are also forthcoming from preference profiles of boundedly rational players, provided that these players instantiate a specific player type and compute partial strategies. We present two structural rules, which are formulated similarly to closure rules for tableaux proofs that restrict players' strategies to a mapping between games in extensive forms (i.e., game trees) and proof trees. Both rules are motivated from players' preferences and limitations; they can therefore be viewed as being player-self-imposable. First-order logical consequence is thus shown to result from playing a specific type of argumentation game. The alignment of such games with the normative model of the Pragma-dialectical theory of argumentation is positively evaluated. But explicit rules to guarantee that the argumentation game instantiates first-order logical consequence have now become gratuitous, since their normative content arises directly from players' preferences and limitations. A similar naturalization for non-classical logics is discussed.

Lecture Notes in Computer Science, 2009

Arguing Global Governance

According to argumentation theory, reasoning takes place in different types of dialogue: persuasion dialogue, negotiation, deliberation, information-seeking dialogue, inquiry, and eristic dialogue. These different dialogue types may be nested within one another. Current research in artificial intelligence is building formal models corresponding to each of these types of dialogue and showing how they can be implemented in, for example, multi-agent communications systems. In this paper, we (1) clarify the distinction between deliberation dialogue and persuasion dialogue, (2) survey some recent research in artificial intelligence studying formal properties of deliberation dialogue, (3) present a model of argumentation in deliberation dialogue that has proved to be useful in electronic democracy, and (4) argue that this model provides an attractive alternative to the dominant cost-benefit model of rational argumentation traditionally accepted in economics and other fields as the basis for evaluating argumentation of the kind used in policy decision making.

2010

We introduce a special family of (assumption-based argumentation) frameworks for reasoning about the benets of decisions. These frameworks can be used for representing the knowledge of intelligent agents that can autonomously choose the \best" decisions, given subjective needs and preferences of decision-makers they \represent". We understand \best" decisions as dominant ones, giving more benets than any other decisions. Dominant decisions correspond, within the family of argumentation frameworks considered, to admissible arguments. We also propose the use of degrees of admissibility of arguments as a heuristic to assess subjectively the value of decisions and rank them from \best" (dominant) to \worst". We extend this method to provide notion of relative value of decisions where preferences over benets are taken into account. Finally, we show how our techniques can be successfully applied to the problem of selecting satellite images to monitor oil spills, to support electronic marketplaces for earth observation products. 2 Background: Assumption-based argumentation Here we provide essential background on assumption-based argumentation (ABA), more details can be found in [4, 13, 10, 14]. An ABA framework is a quadruple hv; ; e; gi where { v is a set of sentences, referred to as language 1 www.argugrid.eu

In this paper we study the complexity of strategic argumentation for dialogue games. A dialogue game is a 2-player game where the parties play arguments. We show how to model dialogue games in a skeptical, non-monotonic formalism, and we show that the problem of deciding what move (set of rules) to play at each turn is an NP-complete problem. 1 Introduction and Motivation Over the years many dialogue games for argumentation have been proposed to study questions such as which conclusions are justified, or how procedures for debate and conflict resolution should be structured to arrive at a fair and just outcome. We observed that the outcome of a debate does not solely depend on the premises of a case, but also on the strategies that parties in a dispute actually adopt. According to our knowledge, this aspect has not received the proper attention in the literature of the field. Almost all the AI literature on the strategic aspects of argumentation (see Section 3 for a brief overview) assumes to work with argument games with complete information, i.e., dialogues where the structure of the game is common knowledge among the players. Consider, however, the following example due to (?) (which in turn modifies an example taken from (?)): p 0 : "You killed the victim." c 1 : "I did not commit murder! There is no evidence!" p 1 : "There is evidence. We found your ID card near the scene." c 2 : "It's not evidence! I had my ID card stolen!" p 2 : "It is you who killed the victim. Only you were near the scene at the time of the murder." c 3 : "I didn't go there. I was at facility A at that time." p 3 : "At facility A? Then, it's impossible to have had your ID card stolen since facility A does not allow a person to enter without an ID card." This dialogue exemplifies an argument game occurring in witness examinations in legal courts. The peculiarity of this game is the fact that the exchange of arguments reflects an asymmetry of information between the players: each player

Practical Reasoning, 1996

Inspired by legal reasoning, this paper presents an argument{ based system for defeasible reasoning, with a logic{programming{like language, and based on Dung's argumentation{theoretic approach to the semantics of logic programming. The language of the system has both weak and explicit negation, and con icts between arguments are decided with the help of priorities on the rules. These priorities are not xed, but are themselves defeasibly derived as conclusions within the system. Apart from varying from domain to domain, priority rules can also be debatable, in the same way as`ordinary' domain information can be. For instance, if an artistic{buildings rule is of an earlier date than a con icting town planning rule, the just{mentioned con ict rule is in con ict with the temporal principle that the later rule has priority over the earlier rule. Other con ict rules may apply to this con ict, and this makes that also reasoning about priorities is defeasible.