Here's the cleanest tale of hypothetical decline I could come up with, keeping away from the more partisan or hysterical scenarios, or those involving a catastrophic deus ex machina.
Imagine that the United States gets through the presidency of Donald Trump without a crippling constitutional crisis. Still, the shrill public debate — which will continue well past Trump’s time in office — will continue to prove unequal to the task of addressing the nation’s most pressing problems.
In recent years, the underlying rate of productivity growth often has been about 1 percent, and rates of economic growth are not even half of what they used to be.