The unprecedented success of Bernie Sanders’s run and his enduring popularity should have been a wake-up call to much of Leftworld: the country is ready for working-class politics, and even for the s-word, as long as we talk about it in everyday, tangible terms.

And yet, much of the radical left learned the opposite lesson from 2016. We have been staking out increasingly wilder terrain, moving the goalposts well beyond what most of the last century’s socialists or communists thought possible. Of course, there’s nothing wrong with horizons — we need them. But the basic challenge of left-wing politics is to train our eyes on horizons that others can see. Social democracy failed not because it traded utopianism for reform but because it swore off horizons entirely, and began to look inwards, upon its own parties and parliaments. In rhetoric, the radical left is different; but in practice, the mistake is similar: victory is defined as whatever makes the already-initiated tick. Ultra-leftism and reformism are united by their scorn for mass action.