Roseanne Barr’s decision on Tuesday to post a tweet comparing a former adviser to President Obama, Valerie Jarrett, to an ape ranks among the predictable developments in an era marked by uncertainty and the unexpected. This was not the first time that Barr has trafficked in social-media racism or directed a simian comparison at an African-American closely connected to the Obama Administration. She has also directed anti-Semitic barbs at George Soros and promoted conspiracy theories pushed by the far left and the far right. ABC moved quickly to cancel Barr’s show, even though it was the top-rated program of the season. Channing Dungey, the president of ABC Entertainment Group, issued a statement calling Barr’s language “abhorrent, repugnant and inconsistent with our values,” and Bob Iger, the C.E.O. of Disney, which owns ABC, called Jarrett to apologize. ABC’s decision was praised as an example of placing values before money, though the largely unasked question was why, given Barr’s track record in recent years, the network didn’t see rebooting “Roseanne” as a violation of those values in the first place.

Donald Trump, who congratulated Roseanne for her high ratings, said nothing about the egregious racism that led to the show’s cancellation. He did, however, deploy his own hallucinatory sense of victimization. Why, he asked, had ABC not apologized for the “HORRIBLE” things it has said about him? That statement functioned on two levels: first, in implying that the network had tolerated equivalent offenses when directed at him, he deflected the idea that Roseanne had done anything beyond bounds. Sarah Huckabee Sanders, the current White House press secretary, followed up on this line in a briefing on Wednesday, when she asked, “Where was Bob Iger’s apology to the White House staff for Jemele Hill calling the President and anyone associated with him a white supremacist?”(Actually, Hill, a commentator on ESPN, which is also owned by Disney, didn’t say that everyone associated with Trump is a supremacist, just that he surrounded himself with them.) The second level of Trump’s remark was that, in pointing to his own wounds, he resorted to the aged, reactionary cliché that the real racists are not bigoted whites but, rather, black people who point out said bigotry.

Roseanne apologized for her joke, on Wednesday, and declared that she was leaving Twitter. But then, again predictably, she resumed tweeting and mused about her options. She had initially told her more than eight hundred thousand followers not to defend her, but they seem to have persuaded her after all that she had been wronged. “You guys,” she told them, “make me feel like fighting back.”

Jarrett, for her part, suggested using the incident as a “teaching moment.” Then, on Saturday, she sent out an e-mail message saying, “When we elect people who continually demean others — those of another race, or religion, or gender, or identity, or sexual orientation — and reach for an America in the past instead of one in the future, the results hurt us all,” and urging people to vote in November.

All this is central to the relief with which some conservatives greeted the news that Samantha Bee, during a monologue on Wednesday, on her television show, “Full Frontal,” called Trump’s daughter Ivanka a “feckless cunt.” In a single profane stroke, the conversation was shifted from Barr’s racism and Trump’s narcissism to the supposed double standard that applies to liberals guilty of unacceptable behavior. Sarah Huckabee Sanders noted that “the collective silence by the left and its media allies is appalling.” Bee apologized, conceding that her joke had “crossed a line.” Her apology, though, served to highlight the chasm between her contrition and the complete absence of the concept in Trump’s public behavior. Trump weighed in on Friday, tweeting, “Why aren’t they firing no talent Samantha Bee for the horrible language used on her low ratings show?”

Yet it’s not the case that indefensible humor directed at Trump has gone unpunished. CNN dispatched Kathy Griffin after she posed for a photo holding a replica of Trump’s severed head. Her career has yet to recover from the tailspin that image initiated. Thus we have a circumstance in which Trump, who has obliterated the norms of propriety in the most powerful office in the land, nonetheless complains about indecency among his opponents. He hypocritically shouts about hypocrisy.

L’affaire Barr would be just another border skirmish in the culture war did it not point to a larger question that seems to have vexed many since Trump’s ascent: Has his antagonism toward norms freed his opponents to flout those same rules, or is it more important than ever that they be upheld? It was the subtext of debates as far flung as whether Al Franken should have been pushed to resign, given that Trump himself has been accused of far worse behavior, or whether it was appropriate to pummel neo-Nazis in Berkeley, given Trump’s even-handed sentiments regarding Charlottesville, and in the reaction to Michelle Wolf’s blistering ridicule of Sarah Huckabee Sanders, at the White House Correspondents’ Association dinner. Michelle Obama famously noted that “when they go low, we go high,” a line Hillary Clinton borrowed on the campaign trail. The question, among hundreds that arose in response to the 2016 election, is, How does that work out in real life?

As my colleague Emily Nussbaum has pointed out, Trump’s insult-comic persona allowed him to portray the groups and the individuals whom he was attacking as dour, humorless marks, who were so fixated on his demise that they treated his jokes as policy statements. The flip side of this has been Trump’s own gossamer-skinned inclinations, the way that he consistently complains about “unfairness” in his Twitter rhetoric. To the outsider, he appears as the classic bully, capable of dishing it out, incapable of taking it. To the truest of his believers, however, he is cast in heroic terms, pointing out his wounds to show how deeply he has suffered on their behalf—a vulgar Jesus showing off his stigmata at the golf club.

Trump’s response to Roseanne was dictated not just by his narcissism but also by his instinctive antagonism toward the old system of norms. It has become common to cast Trump as hostile toward democracy, but his hostilities, like his appetites, are far more basic. They are not aimed at undermining democracy but the norms of decency and accountability that make democracy possible. Samantha Bee was right to apologize; CNN was right to part ways with Griffin. After Charlottesville, the alt-right has been impeded by lawsuits, not by well-aimed left hooks. That Roseanne Barr seems to have decided that maybe she was wronged only affirms the wisdom of ABC’s decision. The threat is not that Trumpism will destroy our sense of decency but rather that it may goad Americans into doing it for him.