The historical reasons for this shift are complex. Although the reasons predate 9/11, the terrorist attacks and the events they set in motion have a lot to do with the rapidity of the change in the last decade. For many liberals, especially Jews, September 11 had the effect of awakening them to the pervasiveness of anti-Semitism in the world, after having long treated anxieties about Jew-hatred as an atavistic obsession of their parents.
For others, however, the attacks triggered what might be called a double backlash. Liberals (and many conservatives), anticipating an outbreak of nationalistic anti-Islamic feeling in an angry and wounded country, admirably took pains to fight negative depictions of Islam. But those laudable demonstrations of toleration sometimes became muddled, leading some liberals, as Leon Wieseltier put it, to start "granting Muslims a reprieve from the rigors of liberalism."
This free pass granted to Islamic fundamentalism often entailed minimizing the key role of anti-Semitism in Islamist ideology. This was seen, most recently, in the wake of Hosni Mubarak's ouster from his dictatorial rule in Egypt, when the op-ed pages and talk shows were awash in commentary insisting there was nothing to fear from the rise of the Muslim Brotherhood, ignoring or downplaying its doctrinal Jew-hatred. In this case and countless others, liberal readers have been tacitly taught to regard any objection to tolerating such extremists as a right-wing talking point—rather than as an assertion of the liberal values they otherwise cherish.
The double backlash could also be seen in foreign policy. The Bush administration's ideology-fueled agenda abroad made many liberals feel that either they were with the president or they were against him—and who would want to be with him? Clinton-era liberal internationalism fell from favor after several of its prominent adherents short-sightedly backed the Iraq War. As the Bush administration grew tight with the Likud governments in Jerusalem, sympathy for Israel came to be equated with a "neocon" position. Those governments, for their part—or at least Benjamin Netanyahu's—often seemed perversely determined to antagonize liberal opinion and alienate friends on the left.
A watershed was reached in 2006 with the publication of Stephen Walt and John Mearsheimer's tract The Israel Lobby. The book trafficked in age-old anti-Semitic stereotypes to conjure up the demon of a cabal of Jews and their allies who led America to war in Iraq against its national interest and were trying to do so again in Iran. Although soberly refuted from many angles, the book uncorked a bottled-up resentment against Israel's American backers, allowing extremist arguments to migrate from the fringes into the mainstream. Coming at the high point of dissatisfaction with the Iraq war, it amplified and encouraged conspiratorial explanations that blamed the decision for war on second-tier neoconservative Jewish officials, like Paul Wolfowitz, more than on top-tier, gentile, not-particularly-neo conservatives like George Bush, Dick Cheney, and Don Rumsfeld.
As these developments opened the door to the frank expression and reflexive rationalization of anti-Semitic views, another, longer-term trend was eroding the cultural taboos against that expression: the vanishing memory of the Holocaust. The murder of 6 million moved the world's conscience enough to finally bless the formation of a Jewish state in 1948. More than six decades later, the generation that liberated the death camps is dying off; so are the survivors. It's becoming easier to treat the Holocaust as part of a dusty history—important to study, like the French Revolution or the fall of Rome, but no more pertinent to today's politics than those long-ago events.
Stanley Fish, the New York Times' most consistently stimulating op-ed columnist and an occasional commentator on matters Jewish, wrote with self-awareness some time ago about his sensitivity to anti-Zionism. It was magnified, he said, by two factors: the time he spends on campuses, "where anti-Israel sentiment flourishes and is regarded more or less as a default position," and his age (now 73). Unlike friends just 10 years younger, Fish remembered World War II—as do his peers everywhere. For decades those memories chilled anti-Semitism and extended the world's concern and protection to the Jewish people. Now they are fading.
In the face of this sad, historical inevitability, what is likely to recommit liberals in America (and the West generally) to a concern with anti-Semitism? It is a question worthy of dispassionate study.