THE crowds sang John Lennon’s “Imagine” at memorial rallies for victims of the weekend shootings in Copenhagen. The anti-religion anthem was an odd choice to express solidarity with Denmark’s Jews, but their leaders were not about to quibble with tens of thousands of Danes offering tearful support. Helle Thorning-Schmidt, the prime minister, proclaimed that “an attack on the Jews of Denmark is an attack on Denmark”—the sort of emphatic language European Jews wanted to hear. A day earlier Binyamin Netanyahu, the Israeli prime minister, had offered a different but equally emphatic take. “Jews have been murdered again on European soil,” he said, adding that “Israel is your home.”

European leaders, and most European Jews, were incensed. Speaking at a French Jewish cemetery desecrated a day after the shootings, President François Hollande rejected Mr Netanyahu’s implication that Jews do not belong in Europe. The French prime minister, Manuel Valls, urged them to stay: “A Jew who leaves France is a part of France that is gone.” In Denmark, the Netherlands, Britain and Germany, Jewish leaders said governments should guarantee Jews’ safety wherever they live, and vowed not to be chased out. “We have to strengthen the Jewish communities in Europe, not panic them,” said Raphael Werner, president of Belgium’s Forum of Jewish Organisations.

Few Jewish leaders disagree with the notion that anti-Semitism in Europe is on the rise. Yet to establish the truth is hard, because anti-Semitism is difficult to measure or even describe. Reports of anti-Semitic incidents are based on differing data and rely heavily on subjective testimony. Assessments of European anti-Semitism tend often to be exaggerated in the Israeli and American press. Indeed, Mr Netanyahu may have been surprised by the uproar that greeted his statements: after all, Zionist leaders were urging Jews to leave Europe in the late 19th century.

There is some evidence that everyday anti-Semitism has risen. Once a phenomenon of the nationalist right, it is now found more among Europe’s Muslims than elsewhere. The Kantor Centre at Tel Aviv University, which compiles international data, says that anti-Semitic attacks have become more frequent in Europe since the early 2000s. Yet both Kantor and the EU’s Agency for Fundamental Rights find that annual numbers have bounced up and down since 2003. They rise in years like 2009 when Israel and the Palestinians are at war. With Israel’s campaign in Gaza last summer, 2014 was a bumper year.

The conflation of Israel with Jews raises thorny questions of when political views cross into bigotry. Palestinian sympathisers accuse pro-Israeli groups of misusing the term “anti-Semitism” to stigmatise legitimate criticism. In July a Belgian doctor who favours sanctions against Israel used the word “Gazacaust” to refer to Israel’s treatment of Palestinians there. To many Jews the term was pure anti-Semitism, but others accepted the comparison. In France Gaza protests have turned into chants of “Death to Jews”; German protesters have sung “Hamas, Hamas, Jews to the gas.” At a rally for solidarity with Gaza, a Dutch rapper called Appa said he was “through with these Zionist dogs, who are out for our money and our blood”. The term “Zionist” did nothing to conceal the latent anti-Semitism, particularly given the hint of old-style blood libels.

Conflicting evidence comes from attitude surveys. A study last November by Fondapol, a French think-tank, found that, whereas 25% of those surveyed agreed that Jews “have too much power in the economy and finance”, the ratio among French Muslims was 67%. In stridently anti-racist Germany a 2010 study found 3% of Germans without any immigrant background agreeing that “Jews have too much power in the world”; the number rose to 25% among those of Turkish origin and 40% among those of Arab origin.

Yet at least among non-Muslim Europeans, anti-Jewish feeling may have declined (see chart). Far-right European political parties once embraced anti-Semitism, but today’s populist-right parties focus on opposing immigration or Islam. The UK Independence Party has stolen the thunder of the quasi-fascist British National Party. France’s National Front has tried to shed its anti-Semitic roots, and the Dutch Party for Freedom is actively pro-Israel. Yet both far-right parties and secular centrist ones can alienate Jews. A Swedish politician from the Centre Party wondered aloud last year why Jews had so much power, yet claimed she was not anti-Semitic; she was forced out, but her party minimised her sentiments as a communication problem.