…but only in theory?
I’m wondering if rather than being tried and found wanting, Keynesianism hasn’t been found impossible and left untried. Whether the amount of stimulus needed to jolt the economy back to trend isn’t simply too large to pass political muster. It’s hard to see a situation short of total war where that kind of money could be authorized or spent in the requisite period of time.
That’s why Krugman wants the space-alien invasion. Works, but only in theory, is how Marxism works, too.