The Republican governor of Utah, Spencer Cox, articulated the feeling of many Americans when he said on CNN a few days after the assassination of the conservative activist Charlie Kirk,  “If your view of America is not shaken right now, then there’s something wrong with you.”

The country has indeed been shaken—not only by last week’s assassination but also this year by the shootings of two state legislators (one of them fatal) in Minnesota, the attempt to burn down the governor’s mansion in Pennsylvania and the death of a police officer in a shooting attack at the headquarters of the Centers for Disease Control and Prevention, as well as at least two attempts on the life of Donald J. Trump as he campaigned for president last year. 

The country should also be shaken by the prospect that these acts of violence, even if irrational and committed by individuals with no coherent political philosophies, could accelerate a slide into authoritarianism and the repression of constitutional rights. Mr. Cox was justified in asking, at the announcement that the suspected assassin of Mr. Kirk had been apprehended, “Is this the end of a dark chapter in our history, or the beginning of a darker chapter in our history?”

“We can return violence with violence, we can return hate with hate, and that’s the problem with political violence—it metastasizes,” Mr. Cox also said at that press conference. “Because we can always point the finger at the other side. And at some point, we have to find an off-ramp, or it’s going to get much, much worse.”

We cannot assume that everyone is looking for that off-ramp. In an interview with Fox News two days after the assassination, President Trump explicitly rejected the idea that extremists on both the left and the right were responsible for encouraging violence, instead insisting, “The radicals on the left are the problem, and they’re vicious and they’re horrible,” and “we just have to beat the hell out of them.”

Some of Mr. Trump’s political allies echoed this threat. The conservative activist and conspiracy theorist Laura Loomer told her 1.7 million followers on X that “The best way President Trump can reinforce Charlie’s legacy is by cracking down on the Left with the full force of the government.” Stephen Miller, the White House deputy chief of staff and a top adviser to the president, wrote on X that the “fate of millions depends upon the defeat of this wicked ideology.” And the Fox News host Jesse Watters told his viewers: “Whether we want to accept it or not, they are at war with us. And what are we going to do about it?”

There are already some indications of what will be done about it. Vice President JD Vance, serving as a guest host of Mr. Kirk’s podcast on Monday, suggested that both individuals and organizations should suffer financially for statements that could be interpreted as “celebrating Charlie’s murder.” “Call them out,” Mr. Vance said. “And hell, call their employer.” Mr. Vance also called for the federal investigation of organizations that fund “left-wing extremism.” As an example, he cited the Ford Foundation for having funded The Nation magazine, which ran a critical article about Mr. Kirk two days after his death—though The Washington Post reports that the Ford Foundation does not seem to have given any money to The Nation for at least five years.

Christopher Landau, the deputy secretary of state, said on X that the government will “undertake appropriate action” against foreign travelers to the United States who are “praising, rationalizing, or making light of” the Kirk assassination. (Does merely pointing out the irony of Mr. Kirk’s opposition to gun control count as “making light”?) A State Department spokesperson told ABC News that Mr. Landau was referring to the longstanding practice of not granting visas to “persons whose presence in our country does not align with U.S. national security interests.” Given the Trump administration’s extremely liberal use of the phrase “national security” to justify deportations without due process and the extrajudicial killings of individuals, there is reason for concern that it will be used to suppress political speech.

In Congress, a Republican representative from Louisiana, Clay Higgins, has urged government action against anyone who “belittled the assassination of Charlie Kirk,” the man who had been celebrated by some as a free speech champion for belittling people like Martin Luther King Jr. “I’m also going after their business licenses and permitting, their businesses will be blacklisted aggressively, they should be kicked from every school, and their drivers licenses should be revoked,” Mr. Higgins wrote. After the Trump administration’s many threats against the news media, it would be understandable for anyone to be concerned about the government taking action against anyone who “belittles” any political ally of the president.

Some of the commentary about Mr. Kirk from the right has been appropriate and inarguable. Vice President JD Vance called him “the smartest and most effective political operative I’ve ever seen” and a “once-in-a-generation figure in American politics.” It is true that an atmosphere of groupthink and intolerance of differing views had descended on some elite college campuses and in some newsrooms before Mr. Kirk built his audience among young people and others who felt unrepresented in political discourse, and he was justified in challenging this status quo. This does not in itself make him a champion of free speech (that phrase describes someone who defends the free speech of others), but his drive and energy are worthy of emulation. 

His legacy should not be the chilling of political debate or honest intellectual arguments. On Sunday, House Speaker Mike Johnson said on Fox News: “People have got to stop framing simple policy disagreements in terms of existential threats to our democracy. You can’t call the other side fascists and enemies of the state and not understand that there are some deranged people in our society who will take that as cues to act.”

Mr. Johnson is correct that framing all policy differences as existential threats to democracy or to the future of the United States is dangerous and corrosive to civil debate. (President Biden had to deal with the same kind of accusations.) He might have added that calling political opponents “un-American” or “treasonous” (as Mr. Trump has repeatedly done) is also playing with fire. And claiming that a sitting president does not “love America,” an accusation made against President Obama by Rudy Giuliani and others, does not exactly turn down the temperature.

But it is also a fundamental right in the United States, and any democracy, to evaluate and publicly comment on a president’s performance in office. Many historians and political scientists are now debating whether the United States is slipping or has already slipped into authoritarianism under Mr. Trump, and even whether the term “fascist” can be properly applied to him. Whether or not you agree with their conclusions, that discussion needs to continue—not despite but because of the threat of political violence.

Robert David Sullivan is the production editor at America magazine. From 2013 to 2016 he wrote a political column called (Un)Conventional Wisdom.