If you’re on the left of British politics, how can you object to a progressive alliance? Don’t you like equality and justice? Do you want the Tories to win? It’s partly the unbearable smugness of the name, the political equivalent of wearing sunglasses on the Tube and admiring your reflection in the windows. But it’s also the inability to think seriously about how any such alliance would work.

Let’s start with the practicalities. Some Labour MPs have called for Labour to stand aside in Brighton Pavilion and Isle of Wight in exchange for the Greens standing aside in Ealing Central and Brighton Kemptown. The rhetoric is the usual, a kumbaya of vacuous niceties: splitting the progressive vote risks letting in the Tories; we’re all on the side of progress and equality; let’s work together for a common cause. But this false equivalency obscures the reality of the situation.

Ealing Central is a fight between Labour and the Conservatives. The excellent Rupa Huq has a majority of just 274 votes. The 2000 votes that the fifth-placed Greens received could be crucial to that contest. But Brighton Pavilion is fight between the Greens and Labour – and if Labour stands down, that puts the Tories into second place. Perhaps the 2000 Green voters in Ealing Central will happily transfer their vote to Rupa Huq, but there’s no reason to think that the 15,000 Labour voters in Brighton Pavilion will reciprocate. Many Labour voters won’t vote for the Greens, and to pretend otherwise is to replace politics with playtime. Taking away the Labour option sends them elsewhere.

Then there’s the distasteful ideology. Why should the Labour Party deny someone the option of voting for it, just because we’ve decided that beating the Tories is the most important thing? Perhaps I refuse to vote for a party, like the Greens, that supports the decriminalisation of prostitution. That’s a reasonable choice to make. Our Prime Minister cynically trades in the illusion that Brexit is the only thing that matters in this election, and some on the left connive in that impression. But housing matters, schools matter, gender justice matters – and someone who doesn’t want to vote for the Greens should be given a left-wing alternative. Voters are not a currency, to be traded where it suits.

Still, opportunity cost is real, and the Labour Party should think clearly and carefully about where it focuses its time and resources. And – ugh, that term – “progressive” voters who live in marginal constituencies should think carefully about how to use their votes and campaigning energy. But I don’t want a progressive alliance. I want the Labour Party to appeal to Green voters and put the Green party out of business. And I want it to appeal to Tory voters and put the Conservative Party out of business. Those of us in the Labour Party will soon have to undertake the hard work of rebuilding the party so that it appeals to voters across the spectrum. But we do so knowing that the Labour Party is the only serious vehicle for left-wing politics. It is make believe to pretend otherwise.

Anil Gomes is Fellow and Tutor in Philosophy at Trinity College, Oxford. His website is: http://www.anilgomes.com