The following correction was printed in the Guardian's Corrections and clarifications column, Thursday April 6 2006

We stated on this article that "it was announced that Prof Walt would step down from his job as academic dean at the end of June" and that "the move had long been planned". A spokesperson for the Kennedy School has asked us to make it clear that the school has made no such announcement linked with the present controversy and that Prof Walt remains there as professor of international affairs.





After the screenwriter Walter Bernstein was placed on the blacklist during the McCarthyite era he said his life "seemed to move in ever-decreasing circles". "Few of my friends dropped away but the list of acquaintances diminished," he wrote in Inside Out, a memoir of the blacklist. "I appeared contaminated and they did not want to risk infection. They avoided me, not calling as they had in the past, not responding to my calls, being nervously distant if we met in public places."

As chair of African American studies in Yale, Paul Gilroy had a similar experience recently after he spoke at a university-sponsored teach-in on the Iraq war. "I think the morality of cluster bombs, of uranium-tipped bombs, [of] daisy cutters are shaped by an imperial double standard that values American lives more," he said. "[The war seems motivated by] a desire to enact revenge for the attacks on the World Trade Centre and the Pentagon ... [It's important] to speculate about the relation between this war and the geopolitical interests of Israel."

"I thought I was being extremely mealy-mouthed, but I was accused of advocating conspiracy theories," says Gilroy, who is now the Anthony Giddens professor of Social Theory at the London School of Economics.

Scot Silverstein, who was once on the faculty at Yale, saw a piece in the student paper about Gilroy's contribution. He wrote to the Wall Street Journal comparing Gilroy to Hitler and claiming his words illustrated the "moral psychosis and perhaps psychological sadism that appears to have infected leftist academia". The Journal published the letter. Gilroy found himself posted on Discoverthenetworks.org, a website dedicated to exposing radical professors. The principle accusation was that he "believes the US fabricated the threat posed by Saddam Hussein".

Then the emails started coming to him and his colleagues, denouncing him. "Only one person said anything," says Gilroy. "Otherwise, nobody looked me in the eye. There was something about the way it never came up that made me realise how nervous and apprehensive they were."

Few would argue there are direct parallels between the current assaults on liberals in academe and McCarthyism. Unlike the McCarthy era, most threats to academic freedom - real or perceived - do not, yet, involve the state. Nor are they buttressed by widespread popular support, as anticommunism was during the 50s. But in other ways, argues Ellen Schrecker, author of Many Are the Crimes - McCarthyism in America, comparisons are apt.

"In some respects it's more dangerous," she says. "McCarthyism dealt mainly with off-campus political activities. Now they focus on what is going on in the classroom. It's very dangerous because it's reaching into the core academic functions of the university, particularly in Middle-Eastern studies."

Either way, a growing number of apparently isolated incidents suggests a mood which is, if nothing else, determined, relentless and aimed openly at progressives in academe.

Earlier this year, Fox news commentator Sean Hannity urged students to record "leftwing propaganda" by professors so he could broadcast it on his show. On the web there is Campus Watch, "monitoring Middle East studies on campus"; Edwatch, "Education for a free nation"; and Parents Against Bad Books in School.

In mid January, the Bruin Alumni association offered students $100 to tape leftwing professors at the University of California Los Angeles. The association effectively had one dedicated member, 24-year-old Republican Andrew Jones. It also had one dedicated aim: "Exposing UCLA's most radical professors" who "[proselytise] their extreme views in the classroom".

Shortly after the $100 offer was made, Jones mounted a website, uclaprofs.com, which compiled the Dirty 30 - a hit list of those he considered the most egregious, leftwing offenders. Top of the list was Peter McLaren, a professor at the UCLA's graduate school of education. Jones branded McLaren a "monster". "Everything that flows from Peter McLaren's mouth and pen is deeply, inextricably radical," wrote Jones. "In keeping with the left's identity politics he has been a friend to the gay community."

McLaren was shocked. "I was away when the story broke and when I came back there were 87 messages waiting for me. I was surprised a list like that could be created in these times. I thought, 'Wow, somebody's out there reading my work fairly carefully.'" The main impact, he says, was to try to insulate those close to him from the fallout. "I had to take down lots of things from my website - family pictures and contacts with other people. I didn't want other people to pay the price."

Also among the Dirty 30 was history professor Ellen DuBois. She was described as, "in every way the modern female academic: militant, impatient, accusatory and radical - very radical". DuBois told the Los Angeles Times, "This is a totally abhorrent invitation to students to participate in a witch hunt against their professors."

McLaren, who describes himself as a marxist-humanist, agrees. He believes the list was a McCarthyite attack on academe, with the aim of softening up public hostility for a more propitious moment: "This is a low-intensity campaign that can be ratcheted up at a time of crisis. When there is another crisis in this country and this country is in an ontological hysteria, an administration could use that to up the ante. I think it represents a tendency towards fascism."

Six weeks after Jones released his list, two Los Angeles county sheriffs arrived unannounced at Professor Miguel Tinker-Salas's office at Pomona College and started asking questions. Tinker-Salas, a Latin American history professor, was born in Venezuela and is a vocal critic of US policy in the region. The sheriffs, part of a federal anti-terrorism task force, told him that he was not the subject of an investigation. Then, for the next 25 minutes they quizzed him on whether he had been influenced in any way by or had contact with the Venezuelan government, on the leadership within the local Venezuelan community, the consulate and the embassy. Then they questioned his students about the content of his classes, examined the cartoons on his door. "They cast the Venezuelan community as a threat," says Tinker-Salas. "I think they were fishing to see if I had any information they could use."

Pomona's president, David Oxtoby, says he was "extremely concerned about the chilling effect this kind of intrusive government interest could have on free scholarly and political discourse."

Last year, some students at the Department of Middle Eastern and Asian Languages and Cultures at Columbia University ran a campaign against alleged anti-Israeli bias among professors, criticising the university as a place where pro-Israeli students were intimidated and faculty members were prejudiced. A faculty committee appointed by Columbia concluded that there had been no serious misconduct.

These issues are not confined to university campuses: it is also happening in schools. Since February, the normally sleepy, wealthy district of Upper St Clair in Pennsylvania has been riven with arguments over its curriculum after the local school board banned the International Baccalaureate (IB), the global educational programme, for being an "un-American" marxist and anti-Christian. During their election campaign, the Republicans of Upper St Clair referred to the IB, which is offered in 122 countries and whose student intake has risen by 73% worldwide in the past five years, as though it was part of an international communist conspiracy, suspicious of a curriculum that had been "developed in a foreign country" (Switzerland). "Our country was founded on Judeo-Christian values and we have to be careful about what values our children are taught," said one Republican board member. Similar campaigns have also sprung up recently at school boards in Minnesota and Virginia.

Meanwhile, in January in Aurora, Colorado, social studies teacher Jay Bennish answered questions in his world geography class about President George Bush's speech from his students at Overland High School. Caricaturing Bush's speech, Bennish said, "'It's our duty as Americans to use the military to go out into the world and make the world like us.'" He then continued: "Sounds a lot like the things Adolf Hitler used to say: 'We're the only ones who are right, everyone else is backwards and it's our job to conquer the world and make sure they all live just like we want them to.' Now I'm not saying that Bush and Hitler are exactly the same. Obviously they're not, OK? But there are some eerie similarities to the tones they use."

Unbeknown to him, one 16-year-old student, Sean Allen, recorded part of the class on his MP3 player. When his Republican father heard it he was so incensed that he shopped it around to local conservative radio stations, where it finally found a home with radio talk-show host Mike Rosen.

Later in Bennish's class, the teacher had told his students, "I am not in any way implying that you should agree with me. I don't even know if I'm necessarily taking a position. But what I'm trying to get you to do is to think, all right, about these issues more in depth, and not just take things from the surface. And I'm glad you asked all your questions because they're all very good, legitimate questions." Rosen only played the first part of the tape on his programme. He also put it on the internet.

The next day, the Cherry Creek school district suspended Bennish, arguing that he had at least breached a policy requiring teachers to be "as objective as possible and to present fairly the several sides of an issue" when dealing with religious, political, economic or social issues.

The suspension sparked rival demonstrations at school. Hundreds of students staged a walkout, a few wearing duct tape over their mouths while some chanted, "Freedom of speech, let him teach." A smaller demonstration was staged against Bennish, with students writing "Teach don't preach" on their shirts.

But it has primarily been universities that have been on the frontline. And on the other side of the trenches has been the rightwing firebrand David Horowitz. Horowitz, who had Jones on his payroll but fired him after the taping controversy, was raised by communist parents and was himself a marxist as a teenager. He is involved with Campus Watch, Jihad Watch, Professors Watch and Media Watch; he was also connected to discoverthenetworks.org, which targeted Gilroy. A few years ago he founded a group, Students for Academic Freedom, which boasts chapters promoting his agenda on more than 150 campuses. The movement monitors slights or insults that students say they have suffered and provides an online complaint form. Students are advised to write down "the date, class and name of the professor", get witnesses, "accumulate a list of incidents or quotes", and lodge a complaint. Over the past three years Horowitz has led the call for an academic bill of rights in several states. The bills would allow students to opt out of any part of a course they felt was "personally offensive" and force American universities to adopt quotas for conservative professors as well as monitor the political inclinations of their staff.

The bill has been debated in 23 states, including six this year. In July, Pennsylvania approved legislation calling on 14 state-affiliated colleges to free their campuses from the "imposition of ideological orthodoxy". Meanwhile, House Republicans have included a provision in the Higher Education Act which calls on publicly funded colleges to ensure a diversity of ideas in class - code for countering the alleged liberal bias in classrooms.

"The aim of the movement isn't really to achieve legislation," says Horowitz. "It's supposed to act as a cattle prod, to make legislators and universities aware. The ratio of leftwing professors in Berkeley and Stanford is seven to one and nine to one. You can't get hired if you're a conservative in American universities."

Reliable empirical, as opposed to anecdotal, evidence to back up Horowitz's claim of political imbalance is patchy but rarely contested. The most detailed study, conducted by California economist Daniel Klein and Swedish scientist Charlotta Stern, did reveal a significant Democratic bias which varied depending on the course they taught. It showed that 30 times as many anthropologists and sociologists voted Democrat as Republican, while for those teaching economics the ration plummeted to three to one.

But these results gave only a partial account of campus life. Limiting their research to the social sciences and the humanities excluded a substantial portion of the university experience. According to the Princeton Review, four of the top 10 most popular subjects - business administration and management, biology, nursing and computer science - are not in the social sciences or humanities. Republicans are probably more inclined to find a home in some of these disciplines. In any case, most academics do not deny that there is a progressive, liberal bias in academe. "Of course," says Todd Gitlin, a professor of journalism and sociology at the Columbia School of Journalism. "There's a lot of conservatives in oil. But there aren't a lot of conservatives planning on studying sociology."

And while liberals may be more numerous, argues Schrecker, a professor of history at Yeshiva University in New York, that does not necessarily mean they are more powerful. "Progressive academe is like the ninth ward of New Orleans before the levees break - neither secure nor particularly safe. It's one of the few areas left with some kind of progressive culture."

That, rather than protection of free expression on campus, is precisely why it remains a target for the right, they say.

In February, Horowitz published a book, The Professors: the 101 Most Dangerous Academics in America, in which he lists, in alphabetical order, the radical academics whom he believes are polluting academe with leftwing propaganda. "Coming to a campus near you: terrorists, racists, and communists - you know them as The Professors," reads the blurb on the jacket. "Today's radical academics aren't the exception - they're legion. And far from being harmless, they spew violent anti-Americanism, preach anti-semitism and cheer on the killing of American soldiers and civilians - all the while collecting tax dollars and tuition fees to indoctrinate our children."

The book is a sloppy series of character assassinations, relying more heavily on insinuation, inference, suggestion and association than it does on fact. Take Todd Gitlin, a journalism and sociology professor at Columbia University. Gitlin was the leader of Students for Democratic Society, a radical anti-war movement in the 60s. Today, his politics could be described as mainstream liberal. He supported the war in Afghanistan but not in Iraq and hung out the Stars and Stripes after the terrorist attacks on September 11. He has recently written a book, The Intellectuals and the Flag, calling for progressives to embrace a patriotic culture that distinguishes between allegiance to one's country, which he supports, and loyalty to one's government, which he does not.

None the less, Horowitz slams him for participating in an anti-war teach-in in March 2003 at which his colleague Nicholas de Genova called for "a million Mogadishus" to be visited on American soldiers in Iraq - referring to the murder of US military in Somalia. But Gitlin has never met or spoken to Genova and was not participating in the teach-in when Genova spoke. Horowitz also slates Gitlin for "immersing students in the obscurantist texts of leftists icons like Jürgen Habermas", but omits to mention that Gitlin also teaches from the works of Plato, Aristotle, Aquinas, Hobbes, Locke, Burke, Adam Smith and the gospels.

"Horowitz's idea of research is cherry-picking," says Gitlin. "And he can't even be trusted to find cherries. He comes up with bitter prunes."

Victor Navasky, the Delacorte professor of journalism at Columbia University, is also on Horowitz's hit list. Navasky, publisher emeritus of the leftwing magazine The Nation and chairman of the Columbia Journalism Review, is accused of "bankrolling" the review and denounced for organising lectures by "prominent leftists" such as Michael Tomasky of American Prospect and Hendrik Hertzberg of the New Yorker. Navasky points out that he has also hosted a lecture by Fox news anchor Bill O'Reilly and the editor of the rightwing Weekly Standard at Columbia, and that the only cheque he ever sent the Review was one he returned after the magazine paid him for an article.

"Were it not for all the inaccuracies I would say that I would be flattered to be on the list, but I don't think I earned it," says Navasky. "I don't think anyone seriously considers me a clear and present danger to the republic."

Horowitz accuses those who accuse him of McCarthyism of being McCarthyites themselves. "All they do is tar and feather me with slanders," he says. "It's the politics of Stalinism."

Evidence to back up his central argument - that these political leanings are at all related to a teacher's ability to be fair, balanced or competent in class - are non-existent. Most of the criticisms of lecturers on both the Dirty 30 list and in Horowitz's book are levelled at comments professors have made outside the classroom and rarely do they provide any evidence of the accused actually criticising or ridiculing students with rightwing ideas.

Nobody denies that bad leftwing lecturers exist. As Russell Jacoby argued in The Nation, "Higher education in America is a vast enterprise boasting roughly a million professors. A certain portion of these teachers are incompetents and frauds; some are rabid patriots and fundamentalists - and some are ham-fisted leftists. All should be upbraided if they violate scholarly or teaching norms. At the same time, a certain portion of the 15 million students they teach are fanatics and crusaders." It is not their work as professors Horowitz does not like; it is the ideologies they espouse, whether in or outside the classroom.

Political assaults on intellectuals are not new. Nor are they specific to the US. At the dawn of western civilisation, Socrates was executed for filling "young people's heads with the wrong ideas". Mao targeted professors for particular humiliation during the cultural revolution.

Mark Smith, the director of government relations for the professor's union, the American Association of University Professors, says that these broadsides vary according to the political climate. Shortly after world war one, the litmus test was those who opposed America's participation in the war or backed the fledgling Russian revolution; during the 50s, it was communists; during the 80s, it was leftwing professors in Latin American studies departments. During the early 90s, Lynne Cheney, the wife of the current vice-president, was chair of the National Endowment for the Humanities, when she lead the bureaucratic charge against "political correctness". In many humanities faculties, she claimed, the common thinking is that "there is no truth. Everything we think is true is shaped by political interests ... Since there is no truth ... faculty members are perfectly justified in using the classroom to advance political agendas."

"These things go in cycles," says Smith. "Horowitz did not invent this. He's capitalising on an ongoing anti-intellectualism and fear of the other."

Many believe that this current cycle has intensified as a result of the official response to 9/11. Two months after the terrorist attacks, the conservative American Council of Trustees and Alumni (ACTA), founded by Lynne Cheney in 1995, branded colleges and universities the "weak link in America's response" to the terrorist attacks and called on lecturers and professors to defend western civilisation. In a report entitled Defending Civilization: how our universities are failing America and what can be done about it, ACTA president Jerry Martin and vice-president Anne D Neal, wrote: "While faculty should be passionately defended in their right to academic freedom, that does not exempt them from criticism. The fact is: academe is the only section of American society that is distinctly divided in its response to the attacks on America."

Regardless of their accuracy, integrity and provenance, some believe that these assaults do have an effect. "There is a cunning behind the battyness," says Gitlin. "It's not just the self-aggrandisement. It's an assault on one of the few social enclaves that the right doesn't control. There is a scattershot bellicosity whether the fortunes of the political right are up or down. They find it useful for fundraising if nothing else."

Others argue that while the individual accounts are troubling, their ultimate effect on academe can be exaggerated. The response to the recent article in the London Review of Books by two prominent American professors arguing that the pro-Israel lobby exerts a dominant and damaging influence on US foreign policy may be a case in point. Stephen Walt and John Mearsheimer have been accused of being anti-semites and bigots, prompting accusations of a McCarthyite witch-hunt. Shortly after publication, it was announced that one of the authors, Walt, was stepping down from his job as academic dean at Harvard's Kennedy School of Government and the school removed the piece from the front page of its website. But the Kennedy School and Walt's colleagues said that the move had long been planned. Meanwhile, the school explained the website change thus: "The only purpose of that removal was to end public confusion; it was not intended, contrary to some interpretations, to send any signal that the school was also 'distancing' itself from one of its senior professors."

"The University of Chicago and Harvard University have behaved admirably in difficult circumstances. We have had the full support of our respective institutions," Mearsheimer said. So all that is left are the accusations which, given the nature of the original article, not even the authors say surprised them. People have a right to be offended. It is when that offence is either based on flawed information or mobilised into an institutional or legislative clampdown that accusations of a witch-hunt truly come into play.

"Clearly these things are disturbing," says Jon Wiener, professor of history at UCLA. "But I don't think they are happening because students are demanding it. The Bruin Alumni Association [turned out] to be one ambitious, well-funded guy. There are some frightening moments, but then things seem to return to normal."

"It's not even clear this is much other than the ill-considered action of a handful, if that, of individuals," says DuBois.

But however many people are involved, the attacks do make a difference, claims Gilroy. "Of course it has an effect," he says. "There's a pre-written script you have to follow and if you chose not to follow it, then there are consequences, so you become very self-conscious about what you say. To call it self-censorship is much too crude. But everybody is looking over their shoulder".