It is a mark of the strange political breakdown that we seem to be experiencing that Her Majesty’s Opposition, at such a vital moment in our nation’s political life, is spending time and attention trying to reassure Jewish people that a future Labour government does not represent an existential threat. What on earth has happened? If, reader, you are tiring of takes on the alleged (m’laud) anti–Semitism in the Labour Party, close your browser now.

Of course, no single explanation will suffice. There is genuine anti–Semitism. There are failures of party management and simple moral leadership. There is, no doubt, a degree of ‘weaponisation’ of the issue by Corbyn’s opponents.

The ultimate source of this bigotry? There is plenty of ideological precedent on the Marxist left, but mainly it is rooted in the kind of politics (right and left–wing brands are available) that leans heavily on the premise that we are all the victim of shadowy undemocratic forces that connive to keep us locked out of power (see this review of Owen Jones’s book on ‘the establishment’). It’s a short step from there to casting the Jews as said subversive influence, drawing on classic stereotypes that have deep roots in European culture and religion.

Here’s another part of the answer which I haven’t yet seen advanced and so commit it to writing here. You can see it in Jeremy Corbyn’s Friday night video. By this point, after months of equivocation, it’s doubtful that anyone was really listening. Nevertheless, his pitch defined why this has become such a problem. “I have spent my life”, said Corbyn, “campaigning for a multicultural society and building recognition of the strength of our diversity” and “Labour exists to promote the social liberation of all people – and that can only be done by uniting people of all ethnic communities and faiths’. All very agreeable, but the implied vision of what the Labour Party is deserves unpacking.

For a politician with a reputation for returning the Labour Party to a more ideological stance – it is very hard to place Corbyn ideologically. The conventional reading is that he is ‘old Labour’, a return to Tony Benn style enthusiasm for state ownership. There’s something in that of course. Corbyn was, for instance, part of Benn’s Independent Left Corresponding Society and saw Benn as something of a mentor. But there’s clearly a strong ‘New Left‘ flavour to Corbynism.

The New Left arose in the 1950s and 1960s, partly through disappointment with the moral and practical failure of Soviet communism. One of the things that marks it out is a focus on cultural as well as political transformation – drawing on grievances of racial and gender inequality, as well as class and economic injustice. Corbyn’s vision of the Labour Party is therefore a rainbow coalition of different ethnic and religious and cultural identity groups and causes, gathering around the principle of ‘social liberation’. You can see it in the way he has harnessed the energy of a plethora of left–wing organisations that have traditionally seen themselves as outside – and indeed, unwanted by – the Labour Party.

In the early Labour party, ethnic, racial, religious and even ideological identities were on the whole downplayed as against class interests. It was not so much interest in their ‘social liberation’ as about having access to decent and decently paid work, a decent place to live, proper healthcare and education. It was also part of the genius of the early Labour Party. It was an institution in which the secular could bond with the religious, the political liberal with the Marxist, the Protestant with the Roman Catholic, the immigrant with the English. Divided interests could find common cause what G. D. H. Cole called a broad movement on behalf of the bottom dog.

At first glance, the early Labour movement and Corbynism seem to resemble each other, but their resemblance is superficial. Interests that happen to overlap and genuinely common interests are not the same thing. Only the latter will prove stable ground for a majoritarian and inclusive left of centre politics, and therefore New Left style politics always risks being fractious and fragile.

This argument seems to contradict the facts of the matter. Hasn’t Corbyn’s leadership been a surprising success? Isn’t there a different energy to his politics? Isn’t this the age of identity and the politics of liberation a most compelling one? Liberation implies oppressors and liberators, and a ‘progressive’ movement gets to casts itself as the chivalrous knight in a cut and dried morality tale. It is exciting to be on the right side of history!

But there are problems.

One is electoral feasibility. In a memorable 2016 article in the New York Times – The End of Identity Liberalism – Mark Lilla, a Columbia University political scientist, argued that Hilary Clinton’s presidential campaign failed because it adopted precisely this rainbow coalition approach. It targeted Latino’s, women, the LGBTQ community, and African–Americans but ignored the working class. “If you are going to mention groups in America, you had better mention all of them”. In the same way, Corbyn could lose either his ‘old’ Labour support – or indeed, depending on how Brexit pans out – his cosmopolitan social liberationist support.

Another is the Pandora’s Box nature of identity politics. Of course, there are minority groups with their own specific needs, grievances and causes. The problem comes when this begins to dominate the political discourse, encouraging everyone to see themselves as a marginalised and victimised. Mark Lilla suggested that the Democratic “obsession with diversity has encouraged white, rural, religious Americans to think of themselves as a disadvantaged group whose identity is being threatened or ignored”. In other words, Clinton eroded the centre ground for which she should have been fighting.

Likewise for Corbyn, it will rightly prove difficult to persuade different races or religious constituencies to yield up their own identities and group concerns when the very principle of the Labour party is their ‘social liberation’. Added to this is the concern that even now Corbyn and others in the Labour Party continue to balance the Palestinian cause and the cause of fighting anti–Semitism in his own party, as if these were a zero sum game. And if he sees it like that, why shouldn’t British Jews?

This is just one example of the ways in which identity politics is shifting political discourse in unpredictable ways. I don’t presume to offer an answer for Corbyn – though it’s hard to see a way out of the immediate political fix without adopting the full International Holocaust Remembrance Alliance definition of anti–Semitism, including the controversial examples. But if I’m right, and the controversy over anti–Semitism is actually just a symptom of a deeper political problem – then his long term task is much harder. That is to forge a genuine movement, built on the common good, not merely lead a crowd who happen to be travelling in a similar direction.