Radicalism and the Revolt Against Reason is a work that continues to have a steady and large scale impact on political and social theory fifty years since its first appearance. A study of how radical thought modifies its actions and ideologies in a time of unrealized and frustrated expectations, the focus is on Georges Sorel and the Europe of the fin de siècle, a time when socialist revolution was forcefully set aside by liberal reform. In a technique that presaged contemporary period, radical demands did not simply dissolve or disappear, they profoundly changed emphasis from the impersonal forces of history to highly personal forces of individual will. This edition includes a substantial brand new introduction by the author.