A number of well-developed theories shed light on the question under what circumstances our
beliefs enjoy epistemic justification. Yet comparatively little is known about epistemic
defeat-when new information causes the loss of epistemic justification. This book proposes and
defends a detailed account of epistemic defeaters. The main kinds of defeaters are analyzed in
detail and integrated into a general framework that aims to explain how beliefs lose
justification. It is argued that defeaters introduce incompatibilities into a noetic system and
thereby prompt a structured re-evaluation process that makes a justified reinstatement of the
defeated belief impossible. The account is then applied to the topic of disagreement where it
is used in an argument for conciliationism as well as a new explanation for higher-order
defeat. Throughout the book the notion of defeat is the center of attention while a number of
new issues are discussed at the intersections of defeat and justification. Specifically new
problems are raised for broadly internalist accounts of defeat a fully descriptive reliabilist
account of defeat is provided and the case for normative defeat is revisited.
