Prioritised Default Logic as Rational Argumentation

We endow Brewka's prioritised default logic (PDL) with argumentation semantics using the ASPIC + framework for structured argumentation. We prove that the conclusions of the justified arguments correspond to the prioritised default extensions in a normatively rational manner. Argumentation semantics for PDL will allow for the application of argument game proof theories to the process of inference in PDL, making the reasons for accepting a conclusion transparent and the inference process more intuitive. This also opens up the possibility for argumentation-based distributed reasoning and communication amongst agents with PDL representations of mental attitudes.