There is, however, another possibility besides a looming liberal crack-up – that a political order can be exhausted and sclerotic, its great ambitions foreclosed and its projects frustrated, and still continue for a good long while without either real reform or real collapse.

That may well be the fate of the liberal order over the next few generations: a kind of sustainable decadence, a zombie existence punctuated by periods of temporary crisis and alarm that continues indefinitely because all of its plausible rivals and inheritors have too many challenges and weaknesses of their own to effectively exploit its incompetence, torpor and stagnation.

In his 1904 poem “Waiting for the Barbarians”, the Greek poet CP Cavafy imagines a Roman-style city where everyone expects the Huns to invade at any moment. When they don’t arrive, there is a “sudden restlessness”, a confusion and even disappointment:

And now, what’s going to happen to us without barbarians?