As the Taliban seize control of Kabul and indeed all of Afghanistan, it is worth pondering the less obvious lessons of this 20-year episode. It is a reminder of why I cannot bring myself to be a foreign policy hawk, even though I largely accept the hawks’ worldview and underlying values.

Let’s put aside whether or not you favor President Joe Biden’s withdrawal, and note that sooner or later it was likely to happen. Former President Donald Trump had favored withdrawal, too, as had earlier Republican presidential candidate Mitt Romney. Trump also negotiated toward that end. Barack Obama’s administration also toyed with the idea of troop withdrawal.

Whether those have been sincere views or cynical posturings, U.S. leadership didn’t exactly send signals of absolute, consistent support for the Afghan government. And thus the problem with foreign policy hawkism is this: American democracy is not very good at making long-term commitments outside our borders. It’s not like the government’s lasting support for, say, Social Security, which has many millions of voters expecting payments. The same can’t be said about Afghanistan policy.

If a country can’t make long-term commitments abroad, it can’t easily reshape the world in its image, or see through hawkish policies. And indeed, the Taliban are in it for the long run and America is not, so it is no wonder they took over Afghanistan so quickly once the U.S. announced its departure. The Afghanis on the ground understood the basic logic here much better than did the Biden administration.

America has made some successful long-term foreign policy commitments, for instance to Germany and South Korea. Those typically date from the Cold War and immediate post-World War II eras, and they are held in place partly by inertia. They also seem to be slowly crumbling. American voters are hardly calling for more such commitments.

The hawks I know, especially those with a politically conservative bent, typically will admit or perhaps even emphasize that the American electorate lacks the stomach for long-term interventions. But rather than consider the practical implications of such an admission, they too quickly flip into moralizing. We hear that the American citizenry is not sufficiently committed, or perhaps that non-conservative politicians are morally bankrupt, or that the Biden administration has made a huge mistake. But those moral claims, even if correct, are a distraction from the main lesson at hand. If your own country is not morally strong enough to see through your preferred hawkish policies, maybe those policies aren’t going to prove sustainable, and thus they need to be scaled back.

I still largely agree with most of the hawk worldview: America can be a great force for good in the world, the notion of evil in global affairs as very real, America’s main rivals on the global stage are up to no good, and there is an immense amount of naivete and wishful thinking in most of those who do not consider themselves hawks. What I do not see is a very convincing recipe for hawk policy success over time.

That all said, I still think the Biden withdrawal from Afghanistan was a policy mistake. The U.S. has allowed a very certain evil to rule about 38 million people, without constraint, and has damaged America’s credibility. The Afghani future never looked promising, but sudden reversals of fortune do occur in world affairs — for instance the Irish peace process of the 1990s or the cessation of war in South America. Hoping for such a reversal, and extending the previous American commitment, seemed a better option. Perhaps the best chance for credibility was, from the beginning, to sell the American public on the notion of a permanent garrison, to forestall disaster, rather than nation-building.

The U.S. never had great options in the first place. In 2001, it was necessary to undertake some form of military action because the U.S. had been attacked from Afghanistan, and further attacks were planned. But when exactly was the right time to withdraw forces? It might have been some year earlier than this, but calculating all of the necessary counterfactuals has always been extremely difficult, and I am suspicious of those who claim to know the right answers with such confidence.

This debate involves a host of untenable views. One camp condemns America’s Afghan interventions but offers few constructive alternatives. Another affiliates with hawkish values, but cannot enforce America’s will. Yet another recognizes the fragility of the current situation, but does not wish to turn over the keys to evil right now and hopes to straggle toward a different set of alternatives.

Very reluctantly, I’ve signed up for the last option.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Tyler Cowen is a Bloomberg Opinion columnist. He is a professor of economics at George Mason University and writes for the blog Marginal Revolution. His books include “Big Business: A Love Letter to an American Anti-Hero.”

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