Book excerpt: This is the first part of Raymond Aron's landmark two-volume study of the sociological tradition—arguably the definitive work of its kind. More than a work of reconstruction, Aron's study is, at its deepest level, an engagement with the very question of modernity: how did the intellectual currents which emerged in the eighteenth century shape the modern political and philosophical order? With scrupulous fairness, Aron examines the thoughts and arguments of the major social thinkers to discern how they answered this question. Volume One explores three traditions: the French liberal school of political sociology, represented by Montesquieu and Tocqueville; the Comtean tradition, anticipating Durkheim in its elevation of social unity and consensus; and the Marxists, who posited the struggle between classes and placed their faith in historical necessity. In his customary clear and penetrating prose, Aron argues that each of these schools offers its own theory of the diversity of societies and that "each is inspired both by moral convictions and by scientific hypotheses." This Routledge Classics edition includes an introduction by Daniel J. Mahoney and Brian C. Anderson.