OF COURSE the left should favour proportional representation if Nick Clegg makes its introduction the price of a deal next week. And it should do so even if the real beneficiary will almost certainly be the hard right.

The proposition  that a party’s representation in a legislative assembly should be broadly in line with the support its platform commands among the population strikes me as logically unassailable. For any serious democratic left, the argument from democracy itself is both sufficient and decisive.

Precisely because the point is unanswerable, supporters of first past the post have always had to dismiss principle by appeal to pragmatism, even if the thinly disguised self-interest is palpable. FPTP, Labour and the Tories have told us for decades, delivers strong and stable government. Translation: FPTP delivers either Labour or Tory governments.

The Labour left twist on this has been to point to continental systems, in which centre parties play the role of kingmakers. In the British context, the suggestion has been that such a set-up could act as a permanent brake on the possibility of a radical Labour administration delivering socialist reforms.

Frankly, neither argument stacks up any more. The outlook for next Thursday leaves an indecisive result the most likely outcome,  while the Lib Dems are if anything to the left of Labour on many issues.

So let’s assume that neither of the big two parties gets an outright majority and Clegg insists on PR as a prerequisite for coalition. There are many available variants, of course, and some of them  are not much of an advance on FPTP.

But let’s further assume we get something like the system used in the Scottish and London assemblies, with seats available to any party able to cross a 5% threshold. Even then, I would not put money on the socialist left being able to meet the challenge.

Optimists will presumably point to the Scottish experience. The Scottish Socialist Party was able to win half a dozen seats in 2003, while neither UKIP nor the British National Party have yet secured even a single place in Holyrood.

By way of a reality check, it has to be pointed out that Scotland instantiates a broadly social democratic political culture in a way that England does not, and moreover, sectarianism scuppered the SSP project soon enough.

A Scottish-style electoral mechanism south of the border would hand the BNP a couple of dozen seats on a plate, while UKIP could conceivably do even better. The hard right would become a meaningful force in national politics in a way that would be beyond its current dreams.

Sure, the Greens would also secure a bunch of MPs, and would become the repository for support from leftists looking for a viable vote. That has to be better than nothing.

But what are the chances of a socialist movement now more fractious, fissiparous and divided than at any point since the formation of the Communist Party in 1920 forming the credible single ticket necessary in the circumstances? Answers in the comments box, please.