Throughout history scepticism and the urge to question accepted truths has been a powerful force for change and growth. Today, as we are bombarded by fake news, adverts, and political rhetoric, a healthy amount of scepticism is widely encouraged. In this book, Duncan Pritchard examines the nature of scepticism, asking when it is problematic. He also examines the philosophical arguments for a radical form of scepticism which maintains that knowledge is impossible, and considers the part scepticism might play in leading a more meaningful life.