I haven’t been counting recently, but it seems as if almost every moderate, liberal, or left-wing pundit and politician who surveys the political future alludes to the prospect of a new McCarthyism. Will a fiercely reactionary Trump administration revive the political repression of the 1940s and ’50s? Will it take as its model a widespread movement that treated dissent as disloyalty, punished thousands of law-abiding Americans, and scared millions more into silence, destroying much of the left and seriously narrowing the political spectrum?

Since I’ve been studying and writing about the McCarthy era for more than 40 years, I’m being asked this question a lot these days. The answer, of course, is “yes and no.”

No, because even our twittering president-to-be doesn’t tweet about a communist threat to American security. And McCarthyism was, above all, a wide-ranging campaign to eliminate communism and all the individuals, institutions, and ideas associated with it from any position of influence within American society.

But, given the certainty that the Trump administration will face determined opposition, attempts to repress it will certainly occur. They will not look exactly like McCarthyism, but they may recycle many of its techniques and objectives. After all, the new regime relies on the same kind of right-wing forces that most actively pushed the anticommunist purges.

One big difference is that the enemy has changed. And political repression does require an enemy, otherwise the authorities will be unable to frighten the nation into accepting massive violations of people’s rights. During the McCarthy era, the supposed threat to the USA was the international communist conspiracy; now it’s Islamic extremists, racial and ethnic minorities, immigrants, and left-wing professors. And they may be dealt with using methods J. Edgar Hoover embraced.

Newt Gingrich, for instance, has called for Congress to revive a World War II–style Un-American Activities Committee. Our president-to-be—who, it’s worth noting, took advice from Joe McCarthy’s sleazy amanuensis, Roy Cohn—has suggested depriving flag-burners of their citizenship. And, just last month, Turning Point USA, a right-wing student organization, posted a “Professor Watchlist” of one or two hundred (the numbers, like McCarthy’s, keep changing) academics who “advance a radical agenda in lecture halls” and make life hard for the conservatives in their classes. Their abuses: criticizing the Republican party, the NRA, and the current Israeli regime.

While it’s unlikely that HUAC will ride again, the current threat to create a Muslim registry recaps one of that committee’s few legislative triumphs. The Internal Security Act of 1950, originally sponsored by Richard Nixon, required the registration of individual Communists and so-called Communist front groups. Because liberal Democrats like Hubert Humphrey were so afraid of being labeled “soft on communism,” they inserted provisions in the measure for rounding up Communists and their allies in the event of an emergency. Though never implemented, the government even planned to resuscitate the former Japanese internment camps to house those supposed threats to the nation’s security. And, of course, the rather amateurish Professor Watchlist harks back to the more toxic blacklists of the 1950s.

Although McCarthyism may not return in its original form, we need to understand how it operated if we are to prevent a recurrence. It was, after all, a uniquely efficacious system of nonviolent political repression that for a decade silenced just about all serious criticism of the status quo.

It did so in accordance with a two-stage procedure. First, the alleged subversives were identified—either by the media or by an official agency like the FBI or a congressional committee—and then they were punished, usually by being fired.

Although a few hundred people went to prison and two—Julius and Ethel Rosenberg –were executed, the main sanctions were economic. People lost their jobs and could rarely find new ones. That blacklisting was remarkably effective—and not just in the entertainment industry. Professors, steel workers, writers, attorneys, longshoremen, school teachers, and anyone else who got caught up in the anticommunist furor could end up out of work and unemployable.

While most attention at the time went to the first stage of McCarthyism—exposure—it was the unheralded (and often secret) participation of public and private employers in its second stage that allowed the witch-hunt to flourish. There was no need for violence. The threat of joblessness sufficed to stifle most dissent.

Besides employers, other elements of American society facilitated the repression. McCarthyism came to dominate domestic politics because most of the nation’s mainstream institutions collaborated with it in one way or another. The Supreme Court, which could have prevented much of what happened, legitimized it instead. During the 1950s, the majority of its members deemed communism such a threat to national security that it did not block the criminal prosecutions, loyalty oaths, congressional inquisitions, and political tests for employment that under normal circumstances it would have ruled against.

Liberals, who should have known better, were also at fault. Upset by the Soviet purges of the 1930s as well as by their memories of unpleasant encounters with party members during the 1930s and ’40s, they came to believe that Communists did not deserve the same constitutional protections as other Americans. Moreover, because they felt so threatened by the GOP’s partisan charges that the New Deal had harbored communism, they purged themselves in self-defense. Labor unions, peace groups, civil-rights organizations, and the liberal wing of the Democratic Party—all rushed to expel the political undesirables in their ranks. Even the ACLU collaborated; with the exception of a few renegade chapters, it would not defend the civil liberties of card-carrying Communists.

That timidity spread to the nation’s colleges and universities as well. Again, with only a tiny handful of exceptions, every school that housed a faculty member who defied HUAC and the other committees decided to investigate that person. Academics who opposed the witch hunt were, it was claimed, professionally unqualified to teach. As dozens of professors lost their jobs for political reasons, the American Association of University Professors (AAUP), the official guardian of academic freedom, was hors de combat.

Eventually McCarthyism petered out. Joe McCarthy self-destructed on TV; the witch-hunters ran out of witches; and the mainstream institutions that had facilitated the anticommunist furor ended their collaboration with the forces of repression. Some even apologized. Whether these institutions learned any useful lessons from their experiences remains to be seen. And whether they are, in any event, able to defend themselves against an intensified campaign against dissent, is also an open question.

The prospect is not encouraging. The federal judiciary will provide no help. Nor will most of the institutions of civil society, hollowed out as they have been by decades of corporatization. The academy remains perhaps the one institution that might still shelter dissent. But it has been under attack for years and, as the cases of people like Norman Finkelstein and Steven Salaita reveal, all too many trustees, presidents, and faculty members seem no more willing to defend unorthodox college teachers than they were in the 1950s.

Still, all is not lost. There are signs that many—though not yet enough—liberals are prepared to fight back. Some talk about emulating the king of Denmark who put on a yellow star when the Nazis invaded his country; they have announced that they will sign up if the new administration forces Muslims to register (a noble sentiment, although it’s not entirely clear this will be possible). Meanwhile, thousands of professors under the aegis of a revitalized AAUP are already taking action; they are petitioning the Watchlist organizers for inclusion on their roster, while others are joining students to create sanctuaries for endangered immigrants. Courage can be contagious. And as increasing numbers of individuals and organizations refuse to collaborate with political repression, the less risky that action will be.

Still, we cannot drop our guard. To do so will allow the creation of an authoritarian regime that will stamp out dissent and create a far more repressive society than either Joe McCarthy or J. Edgar Hoover ever dreamed of.