Just so with the Trumpist and alt-right villages. Different methods and values — but not altogether different. Both draw on similarly cramped ideas about nationhood and sovereignty. Both see political opponents as enemies and immigrants as invaders. Both are susceptible to conspiracy theories. And both feed off the same incessant background noise of Trump-speak. “Lock her up.” “Enemy of the American people.” “Illegal alien mob.”

In other words: the criminalization of political opposition, the vilification of the media, and the demonization of foreigners. At some point, the distance between word and deed becomes short. And then they are joined, as they were last week.

Conservatives used to understand the danger. Why care about social formalities, modes of dress, niceties of speech, qualities of restraint? Not simply because manners make the man, although they do, but because manners also shape political cultures. How does a conservative movement that is supposed to believe that every healthy society needs powerful moral guardrails give itself over to a president whose every other utterance cheerfully knocks those guardrails down?

The Trumpian defense is that no political leader can fairly be held accountable for the acts of followers like Sayoc, much less of avowed opponents like Bowers. Also, what about James Hodgkinson, the Bernie Sanders supporter who shot Republican Representative Steve Scalise last year? But Sanders wasn’t instigating anyone to violence. He wasn’t calling on supporters at his rallies to “knock the crap out of” hecklers, or praising fellow members of Congress for body slamming a reporter.

In an interview on Tuesday with The Times of Israel, Abe Foxman, the former longtime head of the Anti-Defamation League, precisely expresses the president’s level of responsibility for what happened in Pittsburgh.

“Pittsburgh is not Trump,” Foxman says. “It’s also Trump.” Trump, he adds, is not an anti-Semite. But fanning one set of hatreds against immigrants has a way of fanning others, as it did for Bowers when he attacked the synagogue because he was enraged by its support for the Hebrew Immigrant Aid Society.

Turning to last year’s neo-Nazi march in Charlottesville, Foxman says of Trump, “He didn’t create them. He didn’t write their script. He didn’t give them the brown shirts. But he emboldened them. He gave them the chutzpah, that it’s O.K.

“And when he had an opportunity to put it down,” Foxman adds, “he didn’t.” The blood that flowed in Pittsburgh is on his hands, also.

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