This book began as a Ph.D. thesis written in 2011 and defended early in 2012 in the philosophy department of McMaster University. In writing the thesis, and later in turning it into a book, I benefited from the assistance of many friends and colleagues. I am particularly indebted to the following people for their brilliant comments, challenging criticism, and sound advice: Lu?s Duarte d’Almeida, Richard Fallon, Michael Giudice, Stefan Sciaraffa, Natalie Stoljar, Noel Struchiner, Wil Waluchow (my doctoral supervisor), and an anonymous referee for Springer. Noel and Wil deserve special thanks: they are mentors to whom I constantly turn for guidance in all professional matters. I am also very grateful to my parents, Roseli and Farid, and to my wife, Nat?lia, whose loving support has allowed me to complete this and many other challenging projects.