John A. Hall is the James McGill Professor of Comparative Historical Sociology at McGill University in Montreal. He has held previous positions at the London School of Economics and Harvard, and has been a Visiting Professor for many years at the University of Copenhagen. He is the author of books dealing with states in history, nationalism, social theory, and liberalism —most recently, "Ernest Gellner" (Verso, 2010), "The Importance of Being Civil" (Princeton, 2013), "The World of States" (with J.L. Campbell, Bloomsbury, 2015) and "The Paradox of Vulnerability" (with J.L. Campbell, Princeton 2017). While at Princeton, he will be working on the interactions between states, empires, and nations.