 Many people gave me extremely valuable feedback for this entry, or for material which preceded it. I would like to thank David Barnett, Henry Laycock, David Liebesman, Jim McCollum, Thomas McKay, David Nicolas, Jeff Pelletier, Joe Salerno, Adam Sennet, Irem Kurtsal Steen, Jim Stone, and especially Dean Zimmerman. The latter gave me an extraordinary amount of useful feedback and recommendations. I would also like to thank the editors of The Stanford Encyclopedia of Philosophy for their patience. I would like to thank Boğaziçi University Scientific Research Fund for supporting my research for this work (Grant Number: 6668-12B02P1).