Strawmen and eidolons: using argumentation to reason across scenarios

We propose a dialectical argumentation formalism for qualitative reasoning under uncertainty in a context of alternative scenarios. Our formalism extends prior work representing knowledge uncertainty using dialectical argumentation in participant interaction spaces called Agoras. We define the notion of a scenario in this framework and consider its formal properties. In particular, we ask when can two scenarios be considered the same, and how might we aggregate conclusions from debates conducted under different scenarios. Our formalism is a qualitative, argumentation-based generalization of notions of probability of provability.1