How do you weigh a once-in-a-generation transfer of power from private sector to public sector and from capital to labour, against an irreversible rupture with the European Union?
Talk about chalk and cheese, or bicycles versus fish. How on earth do you decide, if you haven't made up your mind already, which you like best?
You could argue that the desire among some voters to squeeze the private sector's pips till they squeak and those that want to take a chainsaw to the UK's ties with the EU - with only a relatively small group apparently wanting both - stem from similar social and economic causes. Namely that the way we've run this place has eroded the living standards, security and a sense of being heard for millions of people, especially those outside the big metropolises, as well as among the young.
I have talked frequently about how there is an element of false consciousness - of trite and misleading populism - in each remedy. But they are the only remedies on offer.
And what is as conspicuous as a meteor hurtling to earth is that the prescriptions on offer from Johnson and Corbyn are so different that even they don't pretend that there is a rational way in the time remaining to choose one over the other.
Corbyn's overarching message is "choose big state now, and you can defer your decision on whether to leave the EU till next year"; Johnson's is "choose to leave the EU at the end of January and we will sort public services out after that".
But even for voters who have a preferred sequence, there are impossible imponderables - such as whether Corbyn or Johnson poses the greater risk to our prosperity (Johnson because he cannot rule out the theoretical possibility that there WILL NOT be a trade deal with the EU by his deadline of the end of December; Corbyn because he cannot rule out the risk of capital flight that would increase the cost of finance and decelerate the economy).
And then there are all the other hideous and impossible trade-offs as you and I weigh up where to put that cross: Labour antisemitism vying with Tory Islamophobia; Johnson's incredible "I never lie" against Corbyn's petulant and unempathetic, "I have said sorry [for antisemitism] in the past".
Which is another way of saying there are hardcore voters who worship Corbyn and Johnson respectively but never together, very few who are indifferent to them, and quite significant numbers who wish a curse on both their houses.
Now all of this explains why Corbyn and Johnson are, with their teams, seeking comfort in doing what they know and do best: in the case of Johnson and his battalion of Vote Leave veterans, sowing mayhem and chaos by painting everyone from television presenters and executives, to Theresa May's and David Cameron's austerity governments as the last and most pernicious enemies of the one true Brexit.
And in the case of Corbyn, putting on his Red Knight armour to keep the hated Trump from turning NHS hospitals into the vassals of America's big-pharma, big-finance industrial complex, while painting Johnson as the American president's craven lacky.
Both Johnson and Corbyn accuse the other of lies, deception and fake news. Such is the new political vernacular. Neither sees the innate contradiction or the tragedy in an election where each prefers the stunt that plays to our emotion and anger to any pretense at reasoned debate.
For the rest of us, there is only one comfort: only another 13 days and it will all be over. Well, actually not all of it. The cancer eating into the credibility of our fundamental institutions will still be there. But this particular acute phase will have passed.