ABSTRACT
The concept of epistemic defeat occupies the center stage in the contemporary theories of knowledge, justification, and reasoning. This is to be expected given the fallibility of our belief-producing processes and the impact of new information on our already held beliefs. Awareness of the new information can sometimes negatively impact the epistemic status of such beliefs, resulting in their revision. Defeaters are considerations that discharge such roles. Discussions of epistemic defeat can be conducted along a number of dimensions. One set of issues concerns the type of entities that are said to have defeating power as well as their targets. Here, it is, for example, customary to distinguish propositional from mental state defeaters. A second set of issues involves the varieties of defeaters and the mechanism by which they discharge their undermining function. This chapter is exclusively concerned with the question of the varieties of defeaters and their mechanism of defeat. In particular, it seeks to show how the phenomenon of higher-order defeat can be accommodated within a general account of epistemic defeat. The main claim of the chapter is that these issues are best handled within the dispositional framework of epistemic reasons and reason-possession.
