Groups engage in epistemic activity all the time. In the philosophy of mind and action there is a matured literature advancing competing theories of what groups are and how they do what they do. More recently, social epistemology has also flourished, expanding and making connections with other areas of philosophy. With these two philosophical lenses now beginning to align themselves, the new vista before us is that of collective epistemology—a natural next step for social epistemology. The essays in this book are essays in collective epistemology, and explore different epistemic aspects of the behaviour of different sorts of group—institutional bodies, the moral community, informal groups, religious communities, the state, or simply the population at large. Each essay has a particular focus that brings it under one of the following broad section headings: Epistemology, Ethics, Political Philosophy, Philosophy of Science. Together the essays indicate the richness and complexity of the philosophical issues generated by thinking about the epistemic life of groups.