This volume delves into the question of how, in an Iberian world apparently far removed from the battlegrounds of modernity and secularisation, doubt and unbelief found fertile soil, stimulated by social and religious developments. Adopting a multidisciplinary perspective, the contributors show how the crisis of identity produced by forced mass conversion touched off inner crises about the nature of Truth. By tracing the path from medieval Spain to the Spanish Inquisition, and from the great literary and artistic works of the Spanish Baroque to Sephardic Marranism, this volume fills a historiographical gap in European social and intellectual history, demonstrating the importance of the Iberian world in the evolution of European scepticism.