Résumé
We propose Statement Graphs (SG), a new logical formalism for defeasible reasoning based on argumentation.Using a flexible labeling function, SGs can capture the variants of defeasible reasoning (ambiguity blocking or propagating, with or without team defeat, and circular reasoning). We evaluate our approach with respect to human reasoning and propose a working first order defeasible reasoning tool that, compared to the state of the art, has richer expressivity at no added computational cost. Such tool could be of great practical use in decision making projects such as H2020 NoAW.