Free-market capitalism, hegemony, Western culture, peace, and democracy--the ideas that shaped world politics in the twentieth century and underpinned American foreign policy--have lost a good deal of their strength. Authority is now more contested and power more diffuse. Hegemony (benign or otherwise) is no longer a choice, not for the United States, for China, or for anyone else. Steven Weber and Bruce Jentleson are not declinists, but...