Last Friday an email from the Labour party – of which I’ve been a member for 44 years – broke my political heart. They wrote coldly to tell me that back in May 2021, I’d committed a crime: retweeting a Lib Dem MP’s call for some voters to back Green candidates in local elections, accompanied by my suggestion that such cross-party cooperation represented “grownup progressive politics”. Why did I say that, why on earth am I facing expulsion for it, and what might it mean for the future of our politics? I said it for two reasons. First, because the progressive majority in our country is thwarted by the electoral system. Votes on the right go almost exclusively to the Tories, but the progressive vote is always split between Labour, Lib Dems and Greens. Under first past the post (FPTP) the Conservatives win on a minority of the vote, again and again. Cooperation between progressives just makes sense. But the real reason I said it is because cooperation is what people do when they have broadly shared goals but bring different attributes and ideas to the table. In every aspect of our daily lives, we succeed when we work respectfully with others. It’s called pluralism, and it celebrates our differences in the sure-fire knowledge that any future worth having is one we negotiate with others rather than one imposed on us. The Labour party was founded on the principle of pluralism: it was a federation of trade unions and socialist societies that cooperated for a common purpose. Its initial electoral breakthrough came in 1906 because the Liberal party stood aside in 30 seats. The spine of Labour’s remarkable 1945 manifesto came from the Liberal minds of John Maynard Keynes and William Beveridge. And then, before 1997, Tony Blair and Paddy Ashdown forged a strong bond to get the Tories out and usher a new Britain in. Today Labour councillors work hand in hand with Greens and Lib Demsto defend communities from Tory cuts. In Wales Labour runs the country successfully in alliance with Plaid Cymru, the Welsh nationalists. This realistic and hopeful politics is the heart and soul of Labour. It finds meaningful expression now in the overwhelming backing of members and unions for proportional representation (PR), so that all votes count equally and thus boost the Lib Dems and the Greens at the expense of the Tories. It suggests a world in which Labour does as well as possible but knows that governing with others is better than losing alone. This is where I stand – on the shoulders of giants such as John Smith, Neil Kinnock, Robin Cook, Mo Mowlam and today, Ed Miliband and Andy Burnham. So, why use an uncontentious tweet from over two years ago to move to expel me? The reason is that the party machine is no longer run in this long and rich spirit of pluralism. It has been captured by a clique who see only true believers or sworn enemies. They are behaving like playground bullies, using people’s desperation to get rid of Tories and the limitations of the voting system to enforce discipline internally and externally. All this is fast amounting to an abusive relationship in which first past the post gives members no realistic alternative party to leave for, and the voters nowhere else to put their cross. PR is the route to a progressive century, but for the Labour machine that would mean sacrificing its domineering power: most of its behaviour now originates in this paranoid, top-down way of political thinking. It doesn’t seem matter to the cliques at the top that even mildly radical policies are being junked or watered down – from rent controls to the £28bn-a-year green transition – or that Labour’s leader chooses the Rupert Murdoch path to power over the progressive majority route. They bat away suggestions that even if Labour rule will be better than the Conservatives, it will not be good enough to deal with a permacrisis world, and its shaky hold on power could dangerously pave the way to authoritarian populism. More than anything, the machine doesn’t care if there’s an absence of hope in its project: it doesn’t matter what you think or feel, so long as you obediently support it. I feel a deep sadness that I’ve tried to do my bit to make Labour a more hopeful, ambitious, generous and compassionate place, and everything has come to this end. I feel the hurt of seeing my MP and activist friends cowed by the fear that they may be next; that they must walk some arbitrary line that keeps them constantly watching their backs. I feel shocked that the factionalism I warned against at the start of the year in these pages has taken its revenge and pretty much proved the point: it’s a petty tyranny. It will be tragic if this is the culture Labour takes into government, because it will fail. And it’s not party bureaucrats who will pay the price, but the nation. Politics can be beautiful or brutal. It can be a place of dreams and hope, collective endeavour, generosity and love. Or it can deny all those things. In his allegorical play The Crucible, about the McCarthyite witch-hunts in the US, Arthur Miller writes: “You know in all your black hearts that this be fraud … You are pulling Heaven down!” Labour’s persecutors and witchfinders aren’t the best of the party, just the people who currently happen to be at the top. They are hard but brittle. Inevitably, like all bullies, they have to be generously but firmly stood up to, until they understand their own insecurities and can start to heal. To my accusers, I therefore send my love. You can fight almost anything but the zeitgeist, that inevitable spirit that shapes our lives. Today, in the face of enormous challenges and opportunities, all we have is our interconnectedness and our shared humanity. Pluralism, that ugly but powerful word, is the force that will shape anything that is progressive. Because it is right, it is good, because it works and people almost everywhere know it. This very human truth is the opposite of the message I was sent in that cold and clinical email. Somewhere in their hearts, I suspect the people who wrote it know that as well. The headline and text of this article were amended on 30 June 2023 to clarify that the author is facing possible expulsion from the Labour party, but is not ‘being expelled’, as an earlier version stated. Neal Lawson is director of the cross-party campaign organisation Compass