Is America finished? Respected public intellectuals, think tank theorists, and members of the media elite seem to think so. The scare headline in a recent New York Times Magazine cover story by Parag Khanna titled “Waving Goodbye to Hegemony” asks, “Who Shrunk the Superpower?” Almost daily, learned authors proclaim The End of the American Era, as the title of a 2002 book by Charles Kupchan put it, and instruct us that the rise of China and India, the reawakening of Putin’s Russia, and the expansion of the European Union signal a profound shift in geopolitical power that will retire once...