This concise and penetrating analysis introduces students to the life and thought of one of the giants of twentieth- century French intellectual life. Portraying Raymond Aron as a great defender of reason, moderation, and political sobriety in an era dominated by ideological fervor and philosophical fashion, Brian Anderson demonstrates the centrality of political reason to Aron's philosophy of history, his critique of ideological thinking, his meditations on the perennial problems of peace and war, and the nature of conservative liberalism. This accessible study of Aron's thought and the thought of his contemporaries will enhance any syllabus for classes on modern and contemporary political thought.