 As one might expect, advocates of the fair-play account have not remained silent in the face of these criticisms. The leading advocate, George Klosko, has written two books elaborating and defending the principle of fairness as the foundation of political obligation (2004 [1992], 2005), and it sometimes seems that every fresh attack on fair play provokes a swift response (e.g., Carr 2002 and Lefkowitz 2004; Zhu 2014 and Tosi 2017). And the attacks have certainly continued (e.g., Simmons 2001, chap. 2; McDermott 2004), as we shall indicate shortly. First, though, it is necessary to see how fair-play advocates have responded to the criticisms sketched above.