In 1996, Tom Paulin, an Oxford don and poet, condemned the literary establishment for tolerating T.S. Eliot's anti-Semitism. Now Harvard stands accused of tolerating the same "malignity" in Mr Paulin. In April he told an Egyptian paper that he thought "Brooklyn-born Jews" who tried to settle in the West Bank should be shot. Despite that, Harvard invited him to deliver a lecture on poetry. The offer was retracted after protests from students and alumni, but renewed when, in the name of free speech, the English faculty voted, with only two abstentions, that he be asked to come. Mr Paulin has accepted.
Harvard's shilly-shallying reflects the current of self-doubt coursing through American academia. One question is where criticism of Israel and its American supporters ends and anti-Semitism begins. Another is what form this criticism should be allowed to take on campuses, many of which have extremely strict "hate codes" for any perceived racism.
Support for Israel remains strong in America. Nevertheless, a "divestment" campaign is asking universities across the country to stop investing money in Israeli firms and in other firms that have Israeli subsidiaries or engage in joint ventures with Israelis. Harvard's investments in such firms, which include Intel, AIG and General Electric, add up to more than $600m. A divestment petition at Harvard and the Massachusetts Institute of Technology has won thousands of signatures.
The spread of the divestment campaign in recent months has added to fears that anti-Semitism is taking hold in American universities. Nasty incidents of intimidation have taken place. Harvard's president, Larry Summers, argues that the divestment campaign unfairly castigates Israel because it is a Jewish state. "My definition of anti-Semitism", says Alan Dershowitz of Harvard Law School, "is taking a trait that is universal and singling out only Israel for exhibiting that trait."
Opponents of divestment argue that many governments commit far worse sins than Israel and yet are ignored by the divestment campaigners. Mr Dershowitz is working with students to prepare mock divestment petitions that would ask universities to divest from Syria, Saudi Arabia and other countries. He says that, though he would be willing to sign divestment petitions for Israel and the rest together, he would not sign one aimed at Israel alone.
The advocates of divestment, recalling that the same weapon was once directed at apartheid South Africa, insist they are not anti-Semitic. Their target, they say, is the relationship between the United States and Israel. Sam Halabi, the leader of Harvard's Justice for Palestine, a student organisation, argues that America in effect finances the occupation and settlement of Palestinian territory. The very fact that Israel is a democracy, unlike the dictatorships around it, suggests it will change its behaviour in response to such pressure.
The row has produced some weird scenes. This month a group of Harvard students launched a "Buy Israel" campaign, selling such things as Israeli military T-shirts, the proceeds from which will be used to buy care packages for Israeli soldiers. At Yale, pro-divestment students set up a "checkpoint", supposedly imitating Israeli checkpoints in the West Bank, where students in military uniforms, carrying fake firearms, stopped fellow students as they went to class.
Another front in the war is to be found on the Internet. Many scholars of Islamic or Middle Eastern affairs have been listed on a website called Campus Watch, established by Daniel Pipes, an academic, and the Middle East Forum, a pro-Israel think-tank. In September, Campus Watch posted the names of eight academics whom it accused of downplaying the dangers of militant Islam or exaggerating Israel's faults. About 100 other academics, in a gesture of solidarity, asked it to add their names to its list. Campus Watch obliged, calling them all "apologists for suicide bombings and militant Islam".
John Esposito of Georgetown University, one of the website's original eight, says he was picked out because he has argued that extremist Islamists are a tiny minority of the Muslim world. After the website posted his name, Mr Esposito began to get hundreds and sometimes thousands of e-mails every day. Some of them contain death threats. Others accuse him of being anti-Semitic, anti-Israeli or un-American.
Campus Watch's defenders say it is making academics, many of them less esteemed than Mr Esposito, publicly accountable for their views and indeed lies (such as saying that no Israelis were killed in the World Trade Centre). And Campus Watch is helping people to exercise the right to free speech (without asking people to shoot each other, as Mr Paulin did). But Mr Esposito still feels targeted: this, he says, will make it even harder for universities to discuss Israel than it already is.