Long-time activist Tom Hayden switched his support from Bernie to Hillary in a deeply thoughtful Nation piece, and some Bernie fans immediately went on the attack. The same pattern has played out repeatedly this election. Individuals who have literally bled to secure our civil rights are verbally savaged for backing the first woman with a viable shot at the presidency. It is a shameful chapter in American politics.

I’m having a ’60s flashback over the kind of aggressive purity politics we see today, and the extreme tactics which have found a nurturing home in the bosom of the Sanders campaign.

Those purists are now attacking Tom Hayden (who was one of the Chicago 7 defendants, along with Abbie Hoffman, Jerry Rubin, and Bobby Seale). I don’t have the room to list all of Tom Hayden’s radical bona fides, but suffice it to say that a lot of progressive jaws dropped when he announced he was switching support from Bernie to Hillary.

Any credibility or good will Tom Hayden might have accumulated through decades of activism and organizing was gone in the blink of an eye. Poof! We recognize the pattern from the earlier attacks on John Lewis, Dolores Huerta, and Elizabeth Warren when she committed the grave sin of refusing to endorse Bernie.

That’s the thing about True Believers™. You can’t grow, you can’t change, and you mustn’t ever deviate. The purity is an end in itself.

I knew many sixties movement dudes, guys who talked a good game but rarely accomplished anything. People who loved to lecture, but didn’t see the difference between free-form activism and actually organizing for change. Most young people were dependable allies of change, in that you could probably count on them to show up for a rally (assuming there was a good enough band as a headliner), if not to vote. But most of them weren’t leaders.

Whether you agree with him or not, Tom Hayden is a leader. He’s done the hard work of organizing for decades. At least give him props for that.

I say “at least” because he’s been regularly attacked through the years for trying to strike that uncomfortable balance between pragmatic liberalism and leftist politics. I remember much moaning and gnashing of teeth after he ran successfully for public office in California, and didn’t embrace every Leftist position. (Alexander Cockburn, one of the purest ponies of them all, once quipped, “In the halls of the national gallery in Washington there are 46 portraits of Benedict Arnold. None look alike, yet they all resemble Tom Hayden.”)

I suspect Tom Hayden’s Catholic, working-class background still informs his macro vs. micro political choices; it does mine. It’s hard to blow up the world when you think about how much people would suffer, especially those who have little to begin with.

When you have financial security (if your parents can afford your bail, you have it), you have more time to think about oppression while the rest of us are at work, trying to survive.

But I digress. What, exactly, did Bernie do after the revolution, after the sit-ins, after the marches? What trail did he blaze? He certainly waited long enough before he prioritized those issues again.

Tom Hayden, on the other hand, never gave up.

Among the more inane responses to his powerful Nation piece was… to deny he ever supported Bernie in the first place! (Bernie supporters “proved” this by linking to a piece he wrote in 2012.)

Retail politics changes people, so I’m sure it changed Tom Hayden. Once you work on the inside, you see how difficult it to change anything, and that makes it a lot harder to demonize those who don’t agree with you — especially when you need to work with them. The white-hot flame of pure righteousness dies down, and instead, you build coalitions, and try to move things forward as much as you can.

I don’t deny the power of outside movements. Like any politics geek, I welcome their ability to drive change that would be excruciatingly slow without them. But when you dig in your heels, and label as corrupt anyone who doesn’t agree with you, it becomes impossible to make even incremental change. Especially when you’re demeaning the most courageous and effective activists of the past half century.

One more thing: Bernie’s supporters hold up a photo of him marching in the sixties as evidence of his credibility on civil rights. But they can’t have it both ways: if they’re asking voters to respect and honor Bernie for his activism, then they can’t malign civil rights heroes simply for choosing a different candidate.

That’s purism gone dreadfully wrong.

[Peter Daou contributed to this article]

(AP Photo/Ernest K. Bennett)