Christopher Winship is the Diker-Tishman Professor of Sociology at Harvard University and a member of the senior faculty at the Harvard Kennedy School of Government. He is affiliated with Harvard’s Institute for Quantitative Social Science and its Center for Public Leadership. He holds a B.A. in sociology and mathematics from Dartmouth College and a Ph.D. in sociology from Harvard. He is currently doing research on several topics: statistical models for causal analysis; the effects of education on mental ability; how people act when rationality is not a possibility; the linkage in pragmatism between action and knowledge; analysis of age period-cohort models; and inner-city youth behavior and violence. With Steve Morgan he is the author of “Counterfactuals and Causal Inference: Methods and Principles for Social Research,” now in its second edition.