Senses of ‘argument’ in instantiated argumentation frameworks

^†This paper was developed from Wyner, Bench-Capon, and Dunne (2009, 2013)

Abstract

Argumentation Frameworks (AFs) provide a fruitful basis for exploring issues of defeasible reasoning. Their power largely derives from the abstract nature of the arguments within the framework, where arguments are atomic nodes in an undifferentiated relation of attack. This abstraction conceals different senses of argument, namely a single-step reason to a claim, a series of reasoning steps to a single claim, and reasoning steps for and against a claim. Concrete instantiations encounter difficulties and complexities as a result of conflating these senses. To distinguish them, we provide an approach to instantiating AFs in which the nodes are restricted to literals and rules, encoding the underlying theory directly. Arguments in these senses emerge from this framework as distinctive structures of nodes and paths. As a consequence of the approach, we reduce the effort of computing argumentation extensions, which is in contrast to other approaches. Our framework retains the theoretical and computational benefits of an abstract AF, distinguishes senses of argument, and efficiently computes extensions. Given the mixed intended audience of the paper, the style of presentation is semi-formal.

Keywords:

• argumentation frameworks
• instantiated argumentation
• structured argumentation
• logic

Acknowledgements

The authors thank the anonymous reviewers for their helpful comments. They also thank the ASPARTIX research group (Egly, Alice Gaggl, and Woltran, 2010) for their useful web application which has been widely used for this research. The authors appreciate the comments from reviewers and conference participants. Errors and misunderstandings rest with the authors.

Conflict of interest disclosure statement

No potential conflict of interest was reported by the authors.

Notes

^† This paper was developed from Wyner, Bench-Capon, and Dunne (2009, 2013)

1. In alternative terminology, we may say to structure arguments, which we use interchangeably.