John J. Mearsheimer is the R. Wendell Harrison Distinguished Service Professor of Political Science at the University of Chicago. He is the author of The Great Delusion: Liberal Dreams and International Realities. He lives in Chicago, IL. Sebastian Rosato is professor of political science at the University of Notre Dame. He is the author of Intentions in Great Power Politics: Uncertainty and the Roots of Conflict. He lives in South Bend, IN.