For those of us watching from the UK, seeing the Democrats grapple with allegations of anti-Semitism in their ascendant left flank has brought on a serious case of déjà vu. For British progressives, it was only a few years ago that we cheered the rise of the left wing of the Labour Party, and the leftward tilt on domestic and foreign policy that followed.

Today, we are spectators from the near future, a place where a full-blown anti-Semitism crisis led to a literal split of the party last week. Viewing American progressive politics today is like seeing the beginnings of a slow-motion car crash, one we’ve already been through.

I have some advice for Democrats looking to avoid the scorched earth on which UK progressives now stand. First, deal with anti-Semitism on the left — and yes, that’s an actual thing, not a smear concocted by political opponents. In fact, this might be the most important advice, namely: Do not let your opponents define the terms of your response to a very real problem.

When accusations of anti-Semitism come from the right, it is all too easy to react defensively, rail against double standards, and cast the issue solely as a weapon of attack rather than a genuine problem. After all, isn’t the right — and especially its Trumpist, far-right faction — far more anti-Semitic? Why is everyone going after one of the first Muslim women in Congress, rather than the white supremacist president and his cronies? Don’t supporters of a rightist, expansionist Israeli government use accusations of anti-Semitism to shut down criticism of its policies?

It’s true: Cynical exploitation of anti-Semitism is as real as anti-Semitism itself.

But focusing only on this creates a decoy that will divide your movement. As we have found to our dismay in the UK, defensiveness can swiftly turn into denialism. And it can bleed into the creation of competing hierarchies of race hate, with the terrible attendant subtext that hatred against Jews is getting special attention.

A progressive movement should instead be built on the premise that an attack on one minority is an attack on all. This is not only how far-right racism actually works, it is also the best way to grow a movement in collective defense against it. With the far-right so frighteningly resurgent politically, Jewish communities look to the left with the expectation of solidarity. Claiming that the left is not as bad as the right on anti-Semitism is not the standard that progressives should aspire to, nor is it one that Jewish people will find reassuring. It’s a good idea to work closely with progressive Jewish groups, even when anti-Semitism isn’t a raging issue and especially with those already part of the left movement. They want to help. Let them.

A refusal to turn anti-Semitism into a political football applies to your own camp too. When complaints of anti-Semitism in the UK Labour Party were amplified by the right of the party, this was seen as another means of undermining the leftist leadership. With supporters of the Corbyn project keen to defend it, anti-Semitism quickly became part of an ongoing factional battle, despite constant pleas from the Jewish community to just not do this.

It has now grown so bad that one Jewish member of Parliament who has faced relentless anti-Semitic attacks — five people, including one Corbyn supporter, were convicted for vile abuse against her, with more investigations currently underway — has now left the party she joined 20 years ago. Her departure is coolly viewed by some Corbyn defenders entirely through the prism of factional fighting. It’s appalling. Don’t let things deteriorate to this point.

Progressives believe in building awareness and educating on issues like anti-Semitism, rather than casting out offenders. That’s good, but don’t let it blind you to the people who don’t want to be educated, or the need to put real space between you and them.

Conspiracy-prone recalcitrants are, with hindsight, easy to identify. They’re the people who insist it’s impossible to criticize Israel without being accused of anti-Semitism, even while progressive Jews are issuing a gazillion suggestions on how to do so without sliding into nasty tropes. They’re the people who reply to talk of anti-Semitism, or Holocaust memorials, with often abusive comments asking, “What about Palestine?” They respond to every claim of anti-Semitism with demands to see evidence, even as they are continually presented with damning examples.

