This work attacks questions that have long troubled social scientists–questions of the cumulative nature of social inquiry. Does the knowledge generated by the study of social, political, and economic life grow more comprehensive over time? Do today’s social scientists in any meaningful sense know more than their intellectual ancestors about such perennial concerns as the origins of war and peace, or the causes of economic growth, or the forces shaping social stratification, or origins of civil upheaval? These questions go to the heart of social scientists’ soul-searching as to whether they are indeed engaged in science.