Tendayi Bloom is a political and legal theorist who focuses on questions of noncitizenship and migration governance. She is author of Noncitizenism: Recognising Noncitizen Capabilities in a World of Citizens (2018) and co-editor (with Katherine Tonkiss and Phillip Cole) of Understanding Statelessness (2017). She carried out the work for the article featured in this issue as part of a Leverhulme Trust Research Fellowship, awarded to her for her project “Noncitizens and the Global Compact for Migration.” She is currently a lecturer in politics and international studies at the University of Birmingham. t.bloom@bham.ac.uk

Gordon Hull is associate professor of philosophy and public policy at the University of North Carolina at Charlotte. He is the author of The Biopolitics of Intellectual Property (forthcoming, 2020) and Hobbes and the Making of Modern Political Thought (2009), as well as numerous articles on privacy, intellectual property, law and technology, and the history of philosophy. ghull@uncc.edu

Robert O. Keohane is professor of international affairs emeritus at Princeton University. He is the author of Power and Governance in a Partially Globalized World (2002) and After Hegemony: Cooperation and Discord in the World Political Economy (1984). He is co-author (with Gary King and Sidney Verba) of Designing Social Inquiry (1994) and co-author (with Joseph S. Nye Jr.) of Power and Interdependence (1977). He has served as the editor of the journal International Organization and as the president of the International Studies Association and the American Political Science Association. He won the Balzan Prize in International Relations: History and Theory in 2017, the Johan Skytte Prize in Political Science in 2005, and the Grawemeyer Award for Ideas Improving World Order in 1989. He is a member of the American Academy of Arts and Sciences, the American Philosophical Society, and the National Academy of Sciences; and he is a corresponding member of the British Academy. His current work focuses on the comparative and international politics of climate change. rkeohane@princeton.edu

Jeff McMahan is the White's Professor of Moral Philosophy at the University of Oxford. He is the author of Killing in War (2009), The Ethics of Killing: Problems at the Margins of Life (2002), and a forthcoming collection of essays called The Values of Lives. jeff.mcmahan@philosophy.ox.ac.uk

Scott D. Sagan is the Caroline S. G. Munro Professor of Political Science, the Mimi and Peter Haas University Fellow in Undergraduate Education, and senior fellow at the Center for International Security and Cooperation and the Freeman Spogli Institute for International Studies at Stanford University. He is the author of The Limits of Safety (1993), Moving Targets (1989), and co-author (with Kenneth N. Waltz) of The Spread of Nuclear Weapons: An Enduring Debate (2012). He was the guest editor of a two-volume special issue of Daedalus: “Ethics, Technology, and War” (Fall 2016) and “The Changing Rules of War” (Winter 2017). ssagan@stanford.edu

Benjamin A. Valentino is associate professor of government at Dartmouth College and coordinator of the War and Peace Studies Program at Dartmouth's Dickey Center for International Understanding. He is the author of Final Solutions: Mass Killing and Genocide in the 20th Century (2004) and co-editor (with Jeremi Suri) of Sustainable Security: Rethinking American National Security Strategy (2016). benjamin.a.valentino@dartmouth.edu

George Vasilev is a research fellow at the University of Melbourne. He specializes in deliberative democracy, nationalism, conflict resolution, minority rights, transnational activism, and Balkan politics. He is author of Solidarity across Divides (2015) and has published his research in such journals as Review of International Studies, Nations and Nationalism, Review of Politics, Critical Review of Social and Political Philosophy, and East European Politics and Societies. george.vasilev@unimelb.edu.au

Michael Walzer is professor emeritus of social science at the Institute for Advanced Study in Princeton, New Jersey. He is the author of many books, including Just and Unjust Wars (1977). His most recent book is A Foreign Policy for the Left (2018). walzer@ias.edu