Ever since the Global Financial Crisis of 2008, a number of leading intellectuals, from both liberal and conservative points on the political spectrum, have been predicting the decline of the United States. The London School of Economics philosopher John Gray responded to the GFC by declaring: “The era of American global leadership is over.” The Yale historian Paul Kennedy revived his doctrine of  “imperial overstretch” to argue that American military spending and the consequent increase in federal debt would soon bankrupt the country.

The conservative Harvard economic historian Niall Ferguson was the most pessimistic of all. In a 2010 paper “Empires on the Edge of Chaos: The Nasty Fiscal Arithmetic of Imperial Decline,” Ferguson said America’s fate would be sealed very quickly. Like other great powers of...