John Gerring is Professor of Government at the University of Texas, Austin. He is the author of Party Ideologies in America, 1828–1996 (Cambridge, 1998), A Centripetal Theory of Democratic Governance (Cambridge, 2008), Concepts and Method: Giovanni Sartori and his Legacy (with David Collier, 2009), Social Science Methodology: A Unified Framework, 2nd edition (Cambridge, 2012), and Applied Social Science Methodology (with Dino Christenson, Cambridge, forthcoming), along with numerous articles.