There is a reason why some people are brought up not to talk about politics at the dinner table. Political discussion is a Molotov cocktail of the personal and the public. It brings out our deepest private convictions and sets them on a collision course with the convictions of others. The effect is often explosive. Politics gets personal very quickly, and it can bring out the worst in us.

In the present phase of the Labour party’s civil war, both sides are now lobbing Molotov cocktails at each other. Bitter personal attacks have been a part of the "new politics" (a phrase which was always going to be hostage to fortune) ever since Jeremy Corbyn’s ascension last summer. The taunts of "Red Tory" and "Blairite scum" still ring in the ears of Labour moderates (or would do if tweets could sound). Now, as the stakes rise, the insults are being returned.

For a while, the Stop Corbyn strategy rested on two traditional critiques: Corbyn cannot win a general election; and he is not a competent leader. In quieter times, these might have been enough. But most of Corbyn’s supporters are unmoved by these arguments. They tend not to see winning elections as important, and are therefore not likely to be persuaded that leadership and competence are important either. What matters to them, above everything else, is "principles" and "integrity". Corbyn’s dogged attachment to his principles is what made him such an authentic voice in last summer’s contest. It remains his strongest suit. When all else about him is shown to be catastrophic for Labour, at least he can claim to be offering a different, "new" type of politics – one which involves less dissembling and a more "straight-talking, honest" approach. In an age of mass disgust for politicians and parties, It’s easy to see the appeal of that.

No wonder, then, that the Stop Corbyn camp have moved on from "he’s incompetent" and "he can’t win" to "he is not who he says he is". The only way to beat him is to weaken his strongest suit. The new line is that Corbyn and those around him are not principled and do not have integrity. Hence the accusations that Corbyn lied about calling for Article 50 to be invoked on 24 June; hence the (faintly absurd) story that Corbyn tried to "bully" MP Conor McGinn into supporting him by phoning his father; hence the focus on Corbyn receiving payment for appearances on a discredited Iranian TV channel; and hence the revelations that Momentum spokesman James Schneider had been "plotting with Tories". It is a campaign designed to make Corbyn supporters question their hero’s integrity. And it is perhaps the last hope for those who want to rid the Labour party of Corbyn’s leadership.

There is a profound critique to be made of Corbyn’s claim to principles. He has spent a lifetime on the moral high ground, pouring scorn on those workaday politicians who grapple in the mud below. But it’s in the mud where politics happens – where things are achieved (or not), where lives are improved (or not). On the high ground, nothing actually happens. It may be principled in one sense to dwell there, but in another it is the height of irresponsibility.

But the emerging Stop Corbyn critique is more personal than that. It’s about Corbyn’s decency as a human being, and not so much about the quality of his politics. There is a sound argument to make about Corbyn’s handling of Labour’s anti-semitism crisis over the summer – but to describe him as a "coward" and "no man at all, let alone a nice one" is to cross over from critique to invective. It is to enter the realm of US political rhetoric, where everyone’s integrity is questioned and where cynicism reigns.

Of course, the attacks have to be sharp if they are going to cut through to the Corbyn support base. And for those MPs and others who have had their integrity viciously maligned by Corbyn supporters, it no doubt feels good for the boot to be on the other foot. But it is a desperate tactic for a desperate cause. Perhaps the attacks will persuade a small number of Corbyn supporters to revisit their assumption that he is principled, but it is unlikely to be enough to swing the leadership election for his challenger, Owen Smith. Meanwhile, the side-effects could cause even longer-term damage to Labour. In the US, negative campaigning has been shown time and again to polarise the electorate and increase public disgust with politics. What will be left of Labour members’ enthusiasm for politics after this brutal fight?

When both sides of a contest are destroying each other, no one really wins. Whatever happens, Labour has been demeaned. The fact that the Stop Corbyn camp has had to resort to personal attacks shows how high the stakes are. But it seems increasingly unlikely that Labour can survive this trench warfare in any meaningful sense.

The party is in grave peril. To have any long-term prospects, Labour will have to stop tearing itself apart at some point. When Clement Attlee was being attacked by Harold Laski for not being left-wing enough, he gave this restrained reply: “A period of silence on your part would be welcome.” I think Labour is crying out for a period of silence. When this leadership contest is over – no matter who wins – perhaps we should all stop talking about politics at the dinner table. At least for a little while.

Will Brett is a Labour councillor in Hackney. He writes in a personal capacity.