Revisiting preferences and argumentation

The ASPIC+ framework is intermediate in abstrac-tion between Dung’s argumentation framework and concrete instantiating logics. This paper gener-alises ASPIC+ to accommodate classical logic in-stantiations, and adopts a new proposal for evalu-ating extensions: attacks are used to define the no-tion of conflict-free sets, while the defeats obtained by applying preferences to attacks, are exclusively used to determine the acceptability of arguments. Key properties and rationality postulates are then shown to hold for the new framework.