But “Is America in decline?” may be the wrong question. The truth is that most of the affluent world — again, the United States, Europe and Japan — faces similar threats.

First: Their welfare states are overwhelmed. Aging societies face a collision between promised benefits and acceptable taxes. Either the first must be cut, or the second must be raised. The politics are poisonous. As the Goldman report notes, how the United States handles its debt creates enormous uncertainty. The same is true elsewhere.

Second: Economic management is breaking down. Before the 2007-09 financial crisis, most economists thought they could avoid deep slumps and engineer acceptable recoveries. Confidence has given way to contentious disagreements. Policies are improvised.

Third: Global markets have run ahead of global politics. Countries depend increasingly on international trade and money flows. But globalized commerce is menaced by nationalistic, ethnic, religious and political differences among nations.

A second American Century, though possible, seems a stretch. The harder question is whether the affluent world can defeat these deeper and more persistent threats to political and economic stability.