 For helpful discussions and comments, Nien-hê Hsieh would like to thank Rahul Kumar, Martin Sandbu, Alan Strudler, Kok-Chor Tan, and Sara Toomey. A special debt of gratitude is given to Walter Sinnott-Armstrong for his support and for his extremely detailed comments and suggestions. Hsieh also would like to thank Jennifer Woo for research assistance.