Last summer, Jeremy Corbyn swept to power in the Labour Party — in spite of his political support for the anti-peace and antisemitic Hamas and Hezbollah. And it did him no damage when it emerged that he had leapt to the defence of Raed Salah, the blood libeller, and Steven Sizer, the 9/11 conspiracist. When the Corbyn campaign accused those who raised the issue of antisemitism of doing so to silence criticism of Israel and to hinder opposition to austerity, Corbyn’s reputation remained intact.

When people realised that he had worked for the Iranian state’s antisemitic TV propaganda channel, nobody seemed to mind.

Labour now has a leader who supports the campaign for a boycott of Israel, who prefers anti-Israel politics to the politics of peace and who has shown himself to be quite unable to recognise antisemitism.

His ally Ken Livingstone recently said that in his 45 years on the left of the Labour Party he had never — not once — seen any antisemitism.

In 2014, Vicki Kirby, a Labour Parliamentary candidate, was warned by the party for posting antisemitic tweets. ‘We invented Israel when saving them from Hitler, who now seems to be their teacher,’ she wrote. She also asked why ISIS was not attacking the ‘real oppressor’, ‘evil’ Israel. It emerged this week that she had been reinstated as a party member and that she was active in the Corbyn support network Momentum; she was then suspended. A picture of Kirby and Jeremy Corbyn, smiling happily together, has been circulating online.

Last week Gerry Downing was expelled from the Labour Party, but only after David Cameron raised his case at Prime Minister’s Questions, after having been allowed to re-join following a previous expulsion. Downing believes that Zionism is at the heart of global capitalism and he advocates re-opening ‘the Jewish Question’. He also said explicitly what Kirby implied — that terrorism is the violence of the oppressed and should never be condemned; it is fundamentally defensive against the real aggression, which is the violence of the global system, of which Jews and Zionism are a key element.

Oxford University Labour Club has been torn apart by Israel-haters who succeeded in drumming out their co-chair Alex Chalmers. Chalmers wrote on his resignation that a large proportion of club members had ‘some kind of problem with Jews’. There was a culture in which the politics of peace between Israel and the Palestinians was mocked as ‘Zio’. A politics of war against Israel was considered more appropriate and the ‘Zios’ were routinely baited with the song ‘Rockets over Tel Aviv’. Jewish students were treated as defenders of racism and apartheid and attempts were made to deny ‘Zio’ members the right to vote in club business. Alex Chalmers wrote that the antisemitic incidents he witnessed were less troubling than the culture which allowed such behaviour to become normalised.

Back in 2011, Labour MP Sir Gerald Kaufman turned to a neighbour on the Commons benches as pro-Israel MP Louise Ellman rose to speak and muttered: ‘Here we are, the Jews again’. He has a record of talking about the influence of ‘Jewish millionaires’ in UK politics and how the Israeli government exploits Holocaust guilt as justification for their murder of Palestinians.

We have just come through ‘Israel Apartheid Week’ on campus. Jewish students are given the choice of keeping silent or standing in the dock to answer charges of racism, imperialism, child-murder and oppression.

University College London Students Union this month voted to support Boycott Divestment and Sanctions against Israel but against no other state. In January, an event put on by pro-peace group Yachad at King’s College, London, was prevented from going ahead when protesters stormed the room.

A significant international academic conference was held last October at Exeter University which normalized the view that Israel is a ‘settler-colonial state’ and so is uniquely illegitimate.

The boycott movement has succeeded in opening up debates across North America about whether Israelis should be excluded from the global sporting, cultural, academic and economic community. Legitimate academic networks such as the American Studies Association and the American Anthropological Association have put their weight behind boycott.

After the murderous attack on the Jewish school in Toulouse, leading academic Tariq Ramadan denied that the killing of Jewish children was antisemitic, insisting that it was really to do with Israel. The attacks on Jews and Jewish targets in Paris, Copenhagen and Brussels did little to raise questions about contemporary antisemitism.

The Palestinian campaign to kill Israeli civilians in the streets has hardly impacted either the news or the political agenda in the Britain.

Owen Jones, Jeremy Corbyn’s most articulate supporter, has this week sounded the alarm about antisemitism in the Labour Party. He says that the old sickness infects progressives as well as the right and he calls for the left to act in solidarity with Britain’s Jews. He says that anyone who responds to the issue of antisemitism by crying ‘Israel’ is part of the problem. But Jones has not yet understood how so many of his comrades fail to see it. He has not yet seen how Kirby, Downing and Kaufman’s worldviews are related to those of Corbyn and Livingstone.

We remember the shoddiness, one-sidedness and the ferocity of Jones’ own condemnation of Israel at the time of the Gaza conflict; we remember his failure to speak out against the campaign to boycott Israel. The crazy, obvious antisemites cannot simply be singled out and expelled from the party like bad apples in a good barrel.

Jones needs to take to heart that there is a relationship between hostility to Israel and antisemitism. Hostility to Israel is partly caused by antisemitism and is also itself a cause of further antisemitism.

In 2012 the key institutions of the Jewish community said that the University and College Union had a problem with institutional antisemitism. Members who opposed the boycott, and the antisemitism which came in its wake, were routinely denounced as supporters of Israeli racism; a string of respected academics resigned from the union in disgust at the treatment they had received; the union stood stonily aloof as Jewish members were denounced as Nazis, as the Torah was portrayed as the source of Israeli racism and as opposition to the boycott was said to be allied to the forces of global capitalism. By 2012, there was hardly anybody left who was willing or able to oppose the boycott campaign at the union’s congress; they had been driven out or silenced.

The Employment Tribunal took the side of the union leadership, saying that raising the issue of antisemitism was an illegitimate and dishonest strategy to silence criticism of Israel, and it seemed ready to punish the Jewish litigant by making him pay the costs.

Fears are now mounting that what Jews experienced in the UCU and in the Tribunal was neither an isolated incident nor an exaggeration, but a prototype of what was to come in the wider labour and progressive movement.

There is no catastrophe. But there is a relentless and incremental deterioration in the ways in which Jews are imagined, described and suspected by many of the people in Britain today who think of themselves as good and clever.

Jewish life in the UK is still rich and free. In spite of legitimate fear of terrorist attack and in spite of the fact that Jewish communal buildings are marked by the fluorescent vests of the Community Security Trust, Jews are not subjected to significant violence on the streets. Antisemitism in Britain today is largely an elite phenomenon. It does not figure hugely in the popular press and in mass culture. It is, so far, a phenomenon about ways of thinking rather than physical violence.

Contemporary antisemitism is carried by people who believe themselves to be opponents of antisemitism; it is neither transparent nor obvious. The antisemites take the high ground, they feel virtuous and courageous. It is an antisemitism which makes Jews feel fearful and lonely, which makes us doubt ourselves and our own judgment. We accuse ourselves of inwardness and of paranoia and our instincts for self-preservation are disrupted and confused. But antisemitism is not a subjective feeling of hatred towards Jews, it is an objective social phenomenon and it can be defined and recognised by those who understand how it works and how it manifests itself.

One key fact about contemporary antisemitism is that it must not be mentioned. Antiracists are educated to assume that talk about antisemitism is an indicator of a Zionist attempt to silence the oppressed Palestinians; it is mis-recognized as the mobilisation of Jewish victim-power, the playing of the Holocaust card. The left is not hostile to Jews when they are powerless and stateless; but it finds it hard to shake the idea that Jews are untrustworthy and are connected to money. The image today is that the Jews have managed to strike a bargain with the American and capitalist devil; instead of playing their role as the symbol of the oppressed, they are conceived of as having saved themselves at the expense of everybody else.

Jews learn to keep quiet about antisemitism because talking about it makes them appear dishonest and selfish. Yet it is becoming increasingly clear that the only way of understanding the weirdness and the menace of contemporary hostility to Israel is to understand it in the context of antisemitic movements and discourses.

But there are reasons for hope. The Jewish Labour Movement — the old Poale Zion — is emerging as a key organising focus within the Labour Party. Labour is at war with itself and it has, for the moment, broken free form its anchor to democratic politics. Academics are organising scholarly responses to their colleagues who teach that Israel is a key evil in the world. Jewish students are defending themselves against antisemitism with courage and with brains.

As well as being a threat to Jews, antisemitism is an indicator of contempt for democratic norms in any movement which tolerates it. Those who fight antisemitism, and the totalitarian movements which feed on it, fight for democracy. They stand for democratic peace, they defend democratic movements, they champion democratic liberty and they argue for democratic equality. So long as Jews understand their resistance to antisemitism as being part of a global struggle for democratic life, they will remain part of a huge, strong, diverse and global movement for freedom.

David Hirsh is Lecturer in Sociology, Goldsmiths, University of London