Abstract
Many epistemologists are attracted to the claim that knowledge possession excludes luck. Virtue epistemologists attempt to clarify this idea by holding that knowledge requires apt belief: belief that is true because of an agent's epistemic virtues, and not because of luck. Thinking about aptness may have the potential to make progress on important questions in epistemology, but first we must possess an adequate account of when a belief is true because of luck. Existing treatments of aptness assume a simple and natural view of luck attribution, according to which the success of a performance is attributable to luck if one of the principal causes of the success is a lucky event. I show that this view is false, and should be replaced. This has major implications for virtue-theoretic accounts of knowledge, as well as the role of luck in epistemology more generally