And here’s where moral clarity is needed. Antisemitism exists, it is a menace, and frightens Jews traumatised by the all too recent Holocaust. Labour must show far greater leadership in tackling antisemitism in the party and rooting out every and any antisemite. But that should not detract from the just cause of showing solidarity with the Palestinian people.

What does the strange irrational hatred called antisemitism consist of? I am not a historian of this vast topic, but personally I define it as the theory that holds Jews responsible for the spilling of the blood of non-Jews.

Antisemitism is a menace. It is not simply the preserve of knuckle-dragging neo-Nazi skinheads; this centuries-old sickness infects progressive circles, too. There are people reading this and thinking "ah, but what about Israel?" I know this because whenever I tweet about antisemitism, someone replies with a sentence along those lines. Sorry to sound self-righteous here, but if that's you, then you're part of the problem.

Anti-Semitism itself is a conspiracy theory... Anti-Semitism differs in this respect from racism, xenophobia, misogyny, and homophobia. Those other bigotries are founded on contempt. Anti-Semitism, like all forms of conspiracism, is founded on paranoia. Which is why people who start down any conspiracy-seeking path so often arrive at anti-Semitism. The pull is hard to resist, because the idea of Jews as arch-manipulators is such a powerful cultural resource.

Anti-Semitism means spreading enmity towards the Jews. When the accursed tsarist monarchy was living its last days it tried to incite ignorant workers and peasants against the Jews. The tsarist police, in alliance with the landowners and the capitalists, organised pogroms against the Jews. The landowners and capitalists tried to divert the hatred of the workers and peasants who were tortured by want against the Jews. In other countries, too, we often see the capitalists fomenting hatred against the Jews in order to blind the workers, to divert their attention from the real enemy of the working people, capital. Hatred towards the Jews persists only in those countries where slavery to the landowners and capitalists has created abysmal ignorance among the workers and peasants. Only the most ignorant and downtrodden people can believe the lies and slander that are spread about the Jews. This is a survival of ancient feudal times, when the priests burned heretics at the stake, when the peasants lived in slavery, and when the people were crushed and inarticulate. This ancient, feudal ignorance is passing away; the eyes of the people are being opened. It is not the Jews who are the enemies of the working people. The enemies of the workers are the capitalists of all countries. Among the Jews there are working people, and they form the majority. They are our brothers, who, like us, are oppressed by capital; they are our comrades in the struggle for socialism. Among the Jews there are kulaks, exploiters and capitalists, just as there are among the Russians, and among people of all nations. The capitalists strive to sow and foment hatred between workers of different faiths, different nations and different races. Those who do not work are kept in power by the power and strength of capital. Rich Jews, like rich Russians, and the rich in all countries, are in alliance to oppress, crush, rob and disunite the workers. Shame on accursed tsarism which tortured and persecuted the Jews. Shame on those who foment hatred towards the Jews, who foment hatred towards other nations. Long live the fraternal trust and fighting alliance of the workers of all nations in the struggle to overthrow capital.

When Sir Keir rightly attacked anti-Semitism in his party, he did not analyse its nature clearly enough. It is not like the old Right-wing anti-Semitism which regarded Jews as creepy foreigners. Rather it a lethally political cocktail of two things – whites on the hard Left who hate anything white, Western or British, and Islamists who, for pseudo-religious reasons, see Jews as the eternal enemy and imagine Allah is telling them to take Palestine by slaughter.

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 mis­recognized as the mobilisation of Jewish victim­power, 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.

For example, in the Labour code it is no longer likely to be antisemitic "to accuse Jewish citizens of being more loyal to Israel, or to the alleged priorities of Jews worldwide, than to the interests of their own nations". The code simply says this is "wrong", as if imprecise or uncivil language is the problem, rather than the prevalence of antisemitic attitudes. Yet this charge, that Jews cannot be trusted or must always be suspected of having a hidden agenda, is central to the old-fashioned, rightwing antisemitism that the Labour party claims to oppose.
Similarly, the IHRA definition says it is antisemitic to compare Israel to Nazi Germany, but Labour's code says this is only the case if there is "evidence of antisemitic intent": a caveat it attaches to all "contentious views" relating to Israel.

And I'll close by saying this. Because anti-Semitism is the godfather of racism and the gateway to tyranny and fascism and war, it is to be regarded not as the enemy of the Jewish people, I learned, but as the common enemy of humanity and of civilisation, and has to be fought against very tenaciously for that reason, most especially in its current, most virulent form of Islamic Jihad. Daniel Pearl's revolting murderer was educated at the London School of Economics. Our Christmas bomber over Detroit was from a neighboring London college, the chair of the Islamic Students' Society. Many pogroms against Jewish people are being reported from all over Europe today as I'm talking, and we can only expect this to get worse, and we must make sure our own defenses are not neglected. Our task is to call this filthy thing, this plague, this — this pest, by its right name; to make unceasing resistance to it, knowing all the time that it's probably ultimately ineradicable, and bearing in mind that its hatred towards us is a compliment, and resolving (some of the time, at any rate) to do a bit more to deserve it. Thank you.

Antisemitism based on purely emotional grounds will always find its ultimate expression in the form of pogroms. A rational antisemitism, however, must lead to the systematic legal fight against and the elimination of the prerogatives of the Jew. ... Its ultimate goal, however, must unalterably be the elimination of the Jews altogether.

Of all the bigotries that savage the human temper there is none so stupid as the anti-Semitic. It has no basis in reason; it is not rooted in faith; it aspires to no ideal; it is just one of those dank and unwholesome weeds that grow in the morass of racial hatred.

Formerly an anti-Semite was somebody who hated Jews because they were Jews and had a Jewish soul. But nowadays an anti-Semite is somebody who is hated by Jews.

The anti‐Semite understands nothing about modern society. He would be incapable of conceiving of a constructive plan; his action cannot reach the level of the methodical; it remains on the ground of passion. To a long‐term enterprise he prefers an explosion of rage analogous to the running amuck of the Malays. His intellectual activity is confined to interpretation; he seeks in historical events the signs of the presence of an evil power. Out of this spring those childish and elaborate fabrications which give him his resemblance to the extreme paranoiacs. In addition, anti‐Semitism channels evolutionary drives toward the destruction of certain men, not of institutions. An anti‐Semitic mob will consider it has done enough when it has massacred some Jews and burned a few synagogues. It represents, therefore, a safety valve for the owning classes, who encourage it and thus substitute for a dangerous hate against their regime a beneficent hate against particular people. Above all this naive dualism is eminently reassuring to he anti‐Semite himself. If all he has to do is to remove Evil, that means that the Good is already given. He has no need to seek it in anguish, to invent it, to scrutinize it patiently when he has found it, to prove it in action, to verify it by its consequences, or, finally, to shoulder he responsibilities of the moral choice be has made. It is not by chance that the great outbursts of anti‐Semitic rage conceal a basic optimism. The anti‐Semite as cast his lot for Evil so as not to have to cast his lot for Good. The more one is absorbed in fighting Evil, the less one is tempted to place the Good in question. One does not need to talk about it, yet it is always understood in the discourse of the anti‐Semite and it remains understood in his thought. When he has fulfilled his mission as holy destroyer, the Lost Paradise will reconstitute itself. For the moment so many tasks confront the anti‐Semite that he does not have time to think about it. He is in the breach, fighting, and each of his outbursts of rage is a pretext to avoid the anguished search for the Good.

One of the worst forms of national enmity is antisemitism, that is to say, racial hostility towards the Jews, who belong to Semitic stock (of which the Arabs forms another great branch). The Tsarist autocracy raised the hunt against the Jews in the hope of averting the workers' and peasants' revolution.