Barry Stroud has since the 1970s been one of the most original contributors to the philosophical study of human knowledge; this volume presents the best of his essays in this area. More than half of the essays are concerned with identifying clearly the question or issue that philosophical theories of knowledge are meant to answer, and with the role of philosophical scepticism in giving the right kind of sense to that question. Another series of essays explores possibilities within the broadly Kantian or 'transcendental' project of establishing the distinctive status and therefore special invulnerability of certain aspects of our conception of the world. Stroud's discussions of these fundamental questions are essential reading for anyone interested in the possibility of philosophical theories of knowledge.