Last Wednesday, on the eve of his election to the House of Representatives, Montana Republican Greg Gianforte beat up Ben Jacobs, a reporter for the British newspaper The Guardian
What prompted the violence? Mr. Jacobs had asked Mr. Gianforte for his reaction to the Congressional Budget Office report showing that the House Republican substitute for the Affordable Care Act would result in 23 million Americans losing their health insurance.
Then, according to a Fox News team who witnessed the brutal attack: "Gianforte grabbed Jacobs by the neck with both hands and slammed him into the ground behind him. ... Gianforte then began punching the reporter. As Gianforte moved on top of Jacobs, he began yelling something to the effect of, 'I'm sick and tired of this!' Jacobs scrambled to his knees and said something about his glasses being broken. ... To be clear, at no point did any of us who witnessed this assault see Jacobs show any form of physical aggression toward Gianforte, who left the area after giving statements to local sheriff's deputies."
After the attack, Mr. Jacobs was evaluated in an ambulance at the scene and taken to Bozeman Health Deaconess Hospital. Several hours later he left the hospital wearing a sling around his arm. Mr. Gianforte was charged with misdemeanor assault.
Donald Trump's reaction? He praised Gianforte's election as a "great win in Montana."
For years, conservatives warned that liberals were "defining deviancy down" by tolerating bad social behavior. Mr. Trump is actively defining deviancy down in American politics. He's also making America meaner.
Last year, Mr. Trump said of a protester at one of his campaign rallies: "I'd like to punch him in the face." He added that "in the old days," protesters would be "carried out on stretchers."
In a different era, when decency was the norm, the members of the U.S. House of Representatives would not seat a thug like Mr. Gianforte in the chamber. But House Republicans seem eager to have another kindred spirit.
Charlie Sykes, a conservative former talk-show host in Wisconsin, told the Washington Post that "every time something like Montana happens, Republicans ... normalize and accept previously unacceptable behavior."
Mr. Gianforte's attack on Mr. Jacobs was shameful enough. Almost as shameful was Mr. Gianforte's press release about what occurred, which blamed Mr. Jacobs. "It's unfortunate that this aggressive behavior from a liberal journalist created this scene at our campaign volunteer BBQ."
It was a blatant lie, as evidenced by the Fox News team and the charge against Mr. Gianforte. But under Mr. Trump, blatant lying is the new normal. And a "liberal journalist" is the enemy.
Kathleen Hall Jamieson, a professor at the University of Pennsylvania's Annenberg School for Communication, told the Post that Mr. Trump "has contributed to a climate of discourse consistent with assaulting a reporter for asking an inconvenient question."
It used to be that candidates and elected officials were supposed to answer reporters' questions. We thought democracy depended on it. But we're now in the era of Donald Trump, who calls the press the "enemy of the American people."
In America, candidates or officials didn't beat up reporters who posed questions they didn't like. That kind of thing occurred in dictatorships.
More generally and menacingly, Mr. Trump has licensed the dark side of the American psyche. His hatefulness and vindictiveness have normalized a new meanness in America.
Since Mr. Trump came on the scene, hate crimes have soared. America has become even more polarized. Average Americans say and do things to people they disagree with that in a different time would have been unthinkable.
"I'd submit that the president has unearthed some demons," Rep. Mark Sanford, a Republican from South Carolina, told the Post. "I've talked to a number of people about it back home. They say, 'Well, look, if the president can say whatever, why can't I say whatever?' He's given them license."
The new meanness is also finding its way into public policy, where Mr. Trump wants unprecedented cuts in Medicaid, Social Security disability and food stamps, and to shove 23 million Americans off health insurance -- all so the rich and corporations can get big tax cuts.
I recall a time in America when this kind of proposal would be considered an affront to decency. Now it's the baseline for negotiations.
A president contributes to the norms of our society. He sets the moral tone. Mr. Trump is setting that tone at a new low.
Robert Reich, a former U.S. Secretary of Labor, is professor of public policy at the University of California at Berkeley and the author of "Beyond Outrage," now available in paperback. His new film, "Inequality for All," is now out on iTunes, DVD and On Demand. He blogs at www.robertreich.org.