 I have benefited, too, from helpful comments, criticisms, and suggestions. For them, I thank Anne Barnhill, Selim Berker, Mark Budolfson, Terence Cuneo, Bob Fischer, Rachelle Gould, Matthew C. Halteman, Elizabeth Harman, Oscar Horta, James John, Robert C. Jones, Jeff McMahan, members of the Vermont Ethics Group, Kate Nolfi, Clare Palmer, L.A. Paul, Tina Rulli, Jeff Sebo, Peter Singer, Sarah Stroud, Mark Timmons, Amy Trubek, and Alisha Utter.