Book excerpt: On Folk Epistemology explores how we ascribe knowledge to ourselves and others. Empirical evidence suggests that we do so early and often in thought as well as in talk. Since knowledge ascriptions are central to how we navigate social life, it is important to understand our basis for making them. A central claim of the book is that factors that have nothing to do with knowledge may lead to systematic mistakes in everyday ascriptions of knowledge. These mistakes are explained by an empirically informed account of how ordinary knowledge ascriptions are the product of cognitive heuristics that are associated with biases. In developing this account, Mikkel Gerken presents work in cognitive psychology and pragmatics, while also contributing to epistemology. For example, Gerken develops positive epistemic norms of action and assertion and moreover, critically assesses contextualism, knowledge-first methodology, pragmatic encroachment theories and more. Many of these approaches are argued to overestimate the epistemological significance of folk epistemology. In contrast, this volume develops an equilibristic methodology according to which intuitive judgments about knowledge cannot straightforwardly play a role as data for epistemological theorizing. Rather, critical epistemological theorizing is required to interpret empirical findings. Consequently, On Folk Epistemology helps to lay the foundation for an emerging sub-field that intersects philosophy and the cognitive sciences: The empirical study of folk epistemology.