Characterising something as antisemitic is a political judgment. It requires knowledge about how antisemitism works, an understanding of context, some thought about intentions, but also analysis of unintended consequences. The working definition, which has now been adopted by the UK Government, offers helpful guidance on the making of such political judgments.

How would you decide whether a joke was antisemitic, or sexist for that matter? You could not invent a machine to do this for you. In part it would depend on whether the joke was funny, on who told it, how and why; on who laughed at it and why they laughed. It is a matter of judgment, and there is room for legitimate disagreement and debate over judgments.

In our time, people who do and think antisemitic things frequently believe themselves to be opponents of antisemitism. Those who single out Israelis and their supporters for boycott angrily deny that they are antisemitic; some who conflate Zionism and Nazism consider themselves to be antiracists; those who say Jews were among the chief financiers of the slave trade or who want to address the ‘Jewish question’ complain they are targets of Zionist smears.

On the level of words, prohibitions and taboos against racism and antisemitism remain firmly in place; but this does not prevent antisemitic and racist ways of thinking becoming ever more significant and influential in public discourse. Because the veneer of respectability is still important, denial and counter-accusations of bad faith tend to drown out rational and democratic discussion.

Antisemitism lurks under the surface; we are reluctant to see it in our allies and we are eager to see it in those we fear or hate. The left sniffs the antisemitism on the right and the right sniffs the antisemitism on the left.

The working definition does not seek to see a person’s essence to find out whether they are antisemitic. What it does instead is to help in the recognition of antisemitic actions and ways of thinking. It is concerned with what people do, what they say and what they tolerate; not what they are.

Many in the movement to boycott and to de-legitimize Israel are afraid of the working definition. They say that it defines criticism of Israel as antisemitic. It actually does the opposite. It helps us to make the distinction between what kinds of criticism may be legitimate and what kinds of hostility or demonization may either lead towards, or result from, antisemitism.

Some on the left will continue to say that the working definition is part of a Zionist and Tory conspiracy to smear left wing politics. This itself is an antisemitic claim.

The left needs to understand antisemitism and to come to terms with the history of antisemitism within its own movement. It needs to educate young people to recognize and oppose antisemitism, not to accuse those who do recognize it of being the problem. The working definition can help us to mobilize against antisemitism. It is not a threat to the left or to those who are for Palestinian freedom, it is a threat to antisemitism.

David Hirsh is a lecturer in sociology at Goldsmiths College, University of London