One idea in particular is going to have to go. Following the Cold War, the American foreign-policy establishment embraced the tragically misguided belief that we could set aside traditional forms of great-power competition and balance-of-power diplomacy while focusing our efforts on “global issues” like human rights, climate change and the construction of an ever-stronger set of international institutions operating under an ever-more-pervasive system of international law.

That destructive consensus rested on two mistaken perceptions. The first was that America’s victory in the Cold War was final and America’s economic and military power plus our diplomatic prestige ensured our unchallengeable supremacy for decades.

The second was that the so-called rules-based world order we were using our power to build would be popular abroad and uncontroversial at home. The economic benefits of the free-market, free-trading world system were so great that no serious country abroad or political movement at home would be insane enough to challenge it. And the elegant international system was going to be so ethically beautiful and politically inspiring that countries all over the world would be irresistibly drawn into it.

The war in Afghanistan illustrates the feckless nature of two decades of American foreign policy.