 I would like to thank Caroline Arruda, Robert Audi, Christine M. Korsgaard, Luca Ferrero, Mark LeBar, Elijah Millgram, Andrews Reath, Tim Scanlon, Robert Schwartz, Michael Smith, Robert Stern, Karsten Stueber and especially David Copp and Connie Rosati, the Editors and Referees of the Stanford Encyclopedia of Philosophy, for their invaluable comments on earlier drafts.