His primary interests are in contemporary political philosophy and ethics as well as their history. He is the co-editor with David Reidy of The Cambridge Rawls Lexicon (2015) and A Companion to Rawls (Blackwell, 2014) and the author of three books: Rawls's A Theory of Justice: An Introduction (2009), Global Justice (2006), and What's Left of Liberalism? An Interpretation and Defense of Justice as Fairness (2000). He has published articles on the work of John Rawls, global justice, public reason, Rousseau, Kant, meta-ethics, and other topics. He teaches courses on contemporary ethical and political philosophy, the history of ethics and political philosophy, and global justice, among other topics. He served as department chair from 2004-2013.