For the past many years and for many years to come, “extremism” has been unacceptable in U.S. politics. One must be in favor of more fossil fuel pipelines under certain strict conditions, not against them entirely. That would be extreme.

The moment when extremism becomes acceptable, or ceases to be extremism, will be the instant before the last human being breathes his or her last breath on a baked and ravaged planet. On that last breath may be the words: “I’ll be a leftist now, I suppose.”

Today, of course, one must be in favor of the good wars and against the bad ones — but not too much against the bad ones. One must not try to abolish war entirely. That would be extreme. So would be banning nuclear weapons.

But in that moment when we know that the nuclear missiles have been launched by the dozens, someone may have the presence of mind to mutter: “Perhaps banning them might have been sort of pragmatic after all. Of course it’s not something worth voting for a third party over. I loved you. Good bye.”

That’s leftism’s moment. It’s a fleeting and final moment in which concerns over offending advertisers might be expected to be somewhat reduced but television viewership should be high. It’s a moment of deep regret in dissonant coexistence with long established habit. It’s a moment that could have erased itself by arriving earlier.

Or maybe that’s not leftism’s moment at all. Maybe leftism’s moment is that instant one finds to pause and rest in during the endless long hectic days of promoting the same obvious perspectives over and over and over again in the struggle against invincible forces that spend half their time golfing.

Of course I’m only kidding. Being a leftist is nothing but free drugs and all-expenses-paid cruises to Moscow, living off the sweat of millions of future billionaires.

Leftism’s moment is perhaps the electoral success (sort of) of Jeremy Corbyn.

I hope so. But what is that moment? It’s a moment of recognizing that UK politics is not as deeply corrupted as US, or of recognizing that peace and justice activism works, or of despair when the Tories keep power anyway, or of renewed and reinvigorated struggle toward victory sometime in the future.

Maybe leftism’s moment is every moment, every straining Sisyphean step up the hill toward a future easier said than made.

Which of the above choices is it?

In the end, I think leftism’s moment will be the moment in which multiple-choice testing is abolished and people are asked to think for themselves. I expect it will come sometime after the apocalypse.