What do snowboarding and British politics have in common?

I snowboard a bit. Every couple of years I hit the slopes, pick up where I left off and get a little better. What I learned in my first few goes is that you get the furthest by making only small course corrections. Left to your instincts, the fear of gathering too much speed makes you want to fully control each turn, to absorb all the momentum so that you can gather your thoughts before initiating the next turn.

This is a terrible approach, since the act of making safe often makes you wobble and fall – most rookie wipeouts are due to this fearful overcompensation. The same effect occurs in early stand-up gigs by the way. Hold the course and all will be well; check in compulsively with how the gig is going and you will project doubt, sending the value of your stock into a tailspin. Credit checks harm your credit rating.

Democratic societies also slalom forwards, tacking to the political left and right as they progress. But they also trend leftwards or rightwards across the mountainside: the political centre is not a fixed place on the mountain but the midpoint of the skiers on the slope. What was left wing in the 1970’s is extreme left wing now, for the centre has drifted rightwards since the 1980s, when Thatcher skidded sharply to the right and then Blair, pragmatically, followed to within hailing distance, always staying within the Overton Window.

I like to drop the Overton Window into conversation whenever I can – my opportunity to do this I call the Overton Window Window. But since you ask, the Overton Window refers to the visible spectrum of ideas tolerated in public discourse, ranging in their political acceptability from actual policy outwards through popular, sensible, acceptable, radical and unthinkable. Politicians who wish to be elected or to remain in office are advised to keep their policy proposals within this range – and over time the range itself is nudged left or right: radical ideas become acceptable, sensible and then policy.

Our parliamentary system of debate is supposed to illuminate this spectrum of opinion. It should work like a courtroom: each side must present its arguments as vigorously as possible, averaging out everybody’s bias and leaving the truths exposed. It is a system that works well at keeping our society on a reasonably even keel – as long as everybody shows up to do their bit in the adversarial process. When, however, one side fails to attend the debate, as in the history-making case of the Remain campaign that never was, the snowboard can lurch unpredictably. Leaving the EU rather than remaining in it and reforming it procedurally will be such a lurch – not leftwards but towards nationalism.

When extreme parties gather grassroots support, they tend of course to siphon it from their ideological near neighbours. To win those votes back, moderate parties can be tempted to tack to the extreme. This risks losing votes from their centrist flank – so they prefer to stay where they are and emit a series of ultrasonic pheeps audible only to the pricked ears of the hardliners, signalling to them that their sympathies are really with them, but that the shills in the mainstream won’t let them say so. It is fair to say that Cameron did not deftly pull this off.

Corbyn, rightly or wrongly a man of genuine principle, has never skied towards the centre. It is the left, the youth vote in particular, that found him again. Despite him being beyond the pale for many, public disenchantment with the excesses of Tory capitalism and the specific incompetence of the current lot may fluke him into office. There he may be able to exert a leftward pull on our notion of normal. If Boris were to repeat May’s error and call a general election to strengthen his parliamentary hand, Corbyn could be in the driving seat before October. I could finish this fantasy happily if I knew what he intends to do about Europe.

The trouble with the European project – and the reason it has split both major parties – is that it represents different things at once to different people. The right in this country think that the EU is socialist. Ask a Greek and you’ll get a very different perspective – they see Europe as a capitalist mechanism for extorting their labour. The word Grexit was in currency back in 2012, when the word Brexit was still a whimsical portmanteau.

It should certainly have stayed that way. We were quite balanced on our snowboard with respect to Europe until Boris and Nigel shouted at us that our course needed drastic correction and we began our long national flail.

I don’t think I will outlive my incredulity at the casual arrogance with which Boris and the other Latin-spouting dummies assured the populace that negotiating an exit deal and new trade deals would be a matter of no difficulty for the Eloquent Ones.

And I don’t think I will outlive my incredulity at the tactical incompetence with which Theresa May triggered Article 50 without any preparation having been done, without any soundings beings taken, without any preliminary trade discussions taking place – and with barely any after either.

We all assume that Boris’s talk of no deal is merely sabre-rattling to strengthen his hand in negotiations with the Europeans. And if he manages not to fall out of office before October and if they believe that he is just crazy enough to crash out, then his lifelong reputation for irresponsibility may yet turn out to have been a strategic preface to this big move. But if it doesn’t come off, if it turns out that substance matters, if they call his bluff, then he – and we – are going to deliver an epic wipeout and this snowy mountainside will be strewn with broken limbs. It’s going to be gnarly.