Reifying default reasons in justification logic

The main goal of this paper is to argue that justification logic advances the formal study of default reasons. After introducing a variant of justification logic with default reasons, we first show how the logic can be used to model undercutting attacks and exclusionary reasons. Then we compare this logic to Reiter’s default logic interpreted as an argumentation framework. The comparison is done by analyzing dierences in the way in which process trees are built for the two logics.