A masterly introduction to epistemology and an original contribution, this book succeeds on both levels. Those who know Michael Williams's earlier work will not be surprised by the rich texture of his writing and by how well it conveys the history and geography of the land of epistemology, while staking out a position of his own within it. Without piling on references, never woodenly didactic, Williams's manuscript still shows his mastery of the subject, in both its historical length and its contemporary breadth. Ernest Sosa, Brown University