A lot of this talk is overstated. Just as the argument about “socialism” among Democrats is more about whether to back Medicare for All than about whether to go #fullMarxist, many conservatives supposedly debating “post-liberalism” are really just debating the balance between libertarianism and economic populism, not preparing to give up on the Constitution. And both debates are taking place in a context defined more by stalemate and stagnation than by a 1930s-style crisis.

But even if overstated, the post-liberal and socialist turns reflect a real change in our politics since the halcyon 1990s. On right and left, it has become easier to imagine ways the liberal order might deserve to fall, because of evils generated from within itself.

On the right, that imagining extrapolates from examples like the Low Countries’ euthanizers toward a future society that remains formally liberal but resembles Aldous Huxley’s “Brave New World” — dominated by virtual reality and eugenics and mood-stabilizing drugs, post-familial and post-religious and functionally post-human. Would such a society deserve the political loyalty of (let us say) a traditional Christian or Muslim, just because it still affords them some First Amendment protections? It is reasonable to say that it might not.

On the left that imagining takes the form of a dire ecological extrapolation — a fear that climate catastrophe isn’t inevitable despite liberalism but because of it, that the combination of governments with limited powers, publics with limited knowledge and corporations with capitalist incentives might be responsible for civilizational disaster. Does this scenario (or other equivalents involving A.I.) call liberal proceduralism into question? For some Carl Schmitts (or Ted Kaczynskis) of the left, it might.

Versions of these imaginings are familiar from past critiques of liberalism. But without being necessarily persuasive, they are more plausible now than 20 years ago, and they explain as much of the flirtation with post-liberalism as xenophobia or millennial ingratitude.

Which means that the liberal order’s defenders need to take them seriously. Liberalism has never done as well as it thinks at resolving its own crises. America’s gravest moral evil, chattel slavery, was defeated by an authoritarian president in a religious civil war, not by proceduralism or constitutional debate. The crisis of the 1930s ended happily for liberalism because a reactionary imperialist withstood Adolf Hitler and a revolutionary Bolshevik crushed him. The liberal peace that followed may depend on fear of the atomic bomb.

All of which hints that a genuinely post-liberal politics might, indeed, someday be required — to save liberal civilization from dystopia or disaster. The post-liberalisms presently on offer are not as serious as either their advocates hope or their critics fear. But if you cannot imagine ever being a post-liberal, left or right, you are not being serious either.

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