Gideon Rosen is Stuart Professor of Philosophy at Princeton University. He is the author (with John P. Burgess) of A Subject With No Object (1997) and numerous essays in metaphysics, moral philosophy, and the philosophy of mathematics. Alex Byrne is Professor of Philosophy at the Massachusetts Institute of Technology. He is co-editor, with David R. Hilbert, of Readings on Color, vols. 1 and 2 (1997) and, with Heather Logue, Disjunctivism (2008). He is currently completing a book on self-knowledge. Joshua Cohen is a faculty member at Apple University, and has taught at MIT (1977-2006) and Stanford (2006-2014). He is the author, co-author, or editor of more than 25 books. His most recent books are Philosophy, Politics, Democracy (2009); The Arc of the Moral Universe (2011); and Rousseau: A Free Community of Equals (2012). Since 1991, Cohen has been editor of Boston Review. Elizabeth Harman is Laurance S. Rockefeller Professor of Philosophy and Human Values at Princeton University. She is the author of “Morally Permissible Moral Mistakes” (Ethics), “The Irrelevance of Moral Uncertainty" (Oxford Studies in Metaethics), “Creation Ethics: The Moral Status of Early Fetuses and the Ethics of Abortion” (Philosophy and Public Affairs), and other essays in moral philosophy. Seana Valentine Shiffrin is Professor of Philosophy and Pete Kameron Professor of Law and Social Justice at UCLA. She is the author of Speech Matters: On Lying, Morality, and the Law (2014), an associate editor of Philosophy and Public Affairs, and a member of the American Academy of Arts and Sciences.