THE related questions of what politics is and what it is for are, naturally, political questions, and once upon a time the answers would have been politically revealing. Whether you think it’s primarily about people, or policy, or principles, or pragmatism (it seems obligatory to be things that begin with ‘p’) ought to offer clues about the kind of politics you favour.

But that seems less clear than it used to. The collective groups to which, in the last century, parties appealed – the industrial working class; the aspirational petite bourgeoisie – have been replaced by less obvious identities. Hence the contradictions in a Conservative government with the highest tax burden to GDP ratio for 30 years and a mania for banning or taxing all manner of activities, and a Labour Party which simultaneously claims to have a radical green agenda and a plan to reintroduce nationalised heavy manufacturing.

Even on the big questions where individual voters may have a very clear stance, such as independence or Brexit, prospective party allegiances are less obvious than one might expect. That’s why, according to both their supporters and critics, the two main UK parties need to get their positions clarified and sold to the electorate.

John McDonnell, the Shadow Chancellor, has been hinting that Labour may formally declare for a second EU referendum, or even Remain, in the face of Jeremy Corbyn’s resistance. Boris Johnson has been assuring Tory members (the only electorate which decides whether he becomes Prime Minister) that he has a new, much improved, plan which involves the UK leaving the EU on October 31, come hell or high water.

I’m not convinced that sorting out Brexit policy will do either party much good, in part because I’m sceptical that it can be sorted out. The Tories at least know that the vast majority of their potential voters are pro-Brexit, but their abysmal record on delivering it – and the results of the European elections – suggest they’re heading for a drubbing. In Leave areas, they’re vulnerable to the Brexit Party, but in Remain constituencies they currently hold, the Lib Dems will presumably be a threat.

Labour has the problem that the parliamentary party is strongly pro-Remain, but supporters and activists (not to mention the leadership) are divided. Mr Corbyn’s policy of unconstructive ambiguity paid off, in that he waited for the Tories to make a hash of it, and they didn’t disappoint, but there’s no confidence about Labour’s alternative, nor even much idea what it is.

READ MORE: Ruth Davidson could be in Brexit negotiating team 

But what matters at the moment is not policy, because there aren’t any good ones, but personnel. Specifically, the parties’ respective leaders.

For Labour, a belated shift to Remain probably won’t help, even if there were now a decisive majority for that in the electorate, something that’s in any case not at all certain. There are plenty of traditional voters disenchanted with the party for other reasons, chief among them Mr Corbyn’s leadership.

Whether it’s the quasi-Marxist economic policy, the knee-jerk anti-Western foreign policy, the continuing failure to tackle what looks more and more like widespread, institutional, anti-Semitism, or simply distrust of Mr Corbyn himself (certainly the chief factor for the wider electorate), Labour’s only hope for revival is ditching the leader. Indeed, all the polling indicates that almost any other Labour MP (except perhaps Mr McDonnell or Diane Abbott) would do better; a halfway decent candidate – Yvette Cooper, say – looks more or less guaranteed to trounce the Tories.

They, in keeping with their more ruthless style, have already ditched Theresa May, though she’s hanging around like a bad smell. Their issue is the opposite one. There’s practically no one, indeed very probably may be no one, who can save them from the richly deserved kicking that the general public is looking forward to giving them when the next election rolls round. They have one hope, if he doesn’t blow up his own campaign, and it is Mr Johnson.

He resembles Mr Corbyn in that he’s popular with his own fan base, and heartily disliked by a great many other people, but there’s some evidence that non-partisan voters may just give him the benefit of the doubt, as they did twice in London, hardly natural Tory territory. True, his opponent was the mad Leftist crackpot Ken Livingstone, but then that’s an argument for his being able to defeat the mad Leftist crackpot currently running Labour. Like Mr Corbyn, too, he’s evasive on detailed policy and there’s plenty of reason to suspect that he makes a lot of it up as he goes along.

READ MORE: Iain Macwhirter: By holding the balance in Westminster, the SNP could end up deciding the fate of Brexit and the Union 

Right now, though, the only question that really counts is which person might get your party elected. For Tories, there’s little to consider, because though Mr Johnson may well mess everything up and/or lose the next election, things can hardly get worse for them. For Labour, it’s the other way round. They almost certainly can’t win with Mr Corbyn in charge, and almost certainly would with almost anyone else.

Of course policies matter for the future of the country, but for the survival of the two main Westminster parties right now, public perception matters more. The Tories have every incentive to deploy their loose cannon, while Labour’s essential priority is to cut theirs loose. The Tories think politics is about power, so will take a chance on Mr Johnson; the Corbynistas think it’s about purity. If they prevail, Labour will miss one of the biggest open goals in political history.