An executable specification of a formal argumentation protocol

We present a specification, in the action language C+, of Brewka's reconstruction of a theory of formal disputation originally proposed by Rescher. The focus is on the procedural aspects rather than the adequacy of this particular protocol for the conduct of debate and the resolution of disputes. The specification is structured in three separate levels, covering (i) the physical capabilities of the participant agents, (ii) the rules defining the protocol itself, specifying which actions are ‘proper’ and ‘timely’ according to the protocol and their effects on the protocol state, and (iii) the permissions, prohibitions, and obligations of the agents, and the sanctions and enforcement strategies that deal with non-compliance. Also included is a mechanism by which an agent may object to an action by another participant, and an optional ‘silence implies consent’ principle. Although comparatively simple, Brewka's protocol is thus representative of a wide range of other more complex argumentation and dispute resolution procedures that have been proposed. Finally, we show how the ‘Causal Calculator’ implementation of C+ can be used to animate the specification and to investigate and verify properties of the protocol.