Rebecca Lowe Coulson was Parliamentary Candidate for the City of Durham at the 2015 General Election.

In the final chapter of Don DeLillo’s second novel, End Zone, a three-hour war game is played out between a nuclear-disaster obsessive, Gary Harkness, and his modern warfare lecturer, ‘the major’. Via numbered steps of increasing destruction, they move towards catastrophe:

(11) Washington, D.C. is hit with a 25-megaton device. New York and Los Angeles are hit with SS-11 missiles.

(12) SIMcap dictates spasm response.

DeLillo’s abstract, almost nonsensical detail reflects the preoccupying incomprehensibility of such a devastating possibility. His protagonist, Harkness – a talented yet ordinary American college football player – finds distracting comfort in on-field tackles, and daydreams of ‘Milwaukee in flames’ that fill him with the self-disgust that is “meant, eventually, to liberate me from the joy of imagining millions dead”.

The year the novel was first published – 1973 – came bang in the middle of the tentative détente between America and the Soviet Union that began with the 1968 Nuclear Non-Proliferation Treaty, and collapsed at the end of the 1970s. A ceasefire was signed in Vietnam in ’73, and Richard Nixon had visited China the previous February. Yet retrospective assumptions of temporary calm ignore the fact that Harkness’s fixation with disaster, while extreme, is surely somehow representative: the contemporary fear of nuclear war was real and all consuming.

Many felt that something so total that it would, in Bertrand Russell’s words, “stop the whole of civilised mankind”, had to be prevented at all costs. To them, any alternative was preferable – even, as DeLillo’s ‘major’ puts it:

“I think what’ll happen in the not-too-distant future is that we’ll have humane wars. Each side agrees to use clean bombs. […] And we actually specify the number of megatons; let’s just say hypothetically one thousand megs for each side. […] So right off the bat you avoid the fallout hazard and millions of bonus kills. […] Of course the humanistic mind crumbles at the whole idea. It’s the most hideous thing in the world to these people that such ideas even have to be mentioned. But this won’t go away. The thing is here and you have to face it.”

And it’s that feeling of all-out, anything-will-do urgency – nails dragging into the cliff to slow your fall; the superhuman kneeing of the guy in his stomach to stop him taking you away – that Jeremy Corbyn’s practised comments on disarmament seem to miss. The pre-election BBC Question Time special, in which he refused to commit to the idea of a nuclear “first strike”, ended with a woman commenting: “I don’t understand why everyone in this room [aside from Corbyn] seems so keen on killing millions of people” – words that quickly hit the social media world.

In my last column, I wrote about the need for the Centre-Right to remake the old arguments they could once depend on voters already knowing. The argument for deterrence is one of those. I also wrote about how we should remember that our political ‘sides’ agree more substantially than they admit. In a modern country like Britain, there is significant overlap between the ends that most of us desire; it’s usually on the detail of our proposed approaches to reach those ends that we disagree. The deterrence argument exemplifies this.

Contrary to the implication of the Question Time woman’s comment, those favouring deterrent approaches – including a commitment to the ‘second use’ of weapons – do so because they want to prevent the deaths of millions of people. They want to provide advance reasons to prevent their opponents from killing people. This is not a debate about whether or not to have a nuclear war; it’s about the best way of avoiding one.

Corbyn recognises that, of course. As he said at Chatham House during the run-up to the election: “Labour’s support for the renewal of the Trident submarine system does not preclude working for meaningful, multilateral steps to achieve reductions in nuclear arsenal”. During that speech, he also committed to increased defence spending, and clarified that he wasn’t a pacifist. He talked of the need to “walk the hard yards”, and, in the face of untrustworthy enemies, that’s what deterrence has always been all about.

As with Brexit – its negotiations providing another great example of the war-gaming tactic of the “ultimate threat” – Corbyn has proved himself a consummate politician. He says one thing to his trusties: sweet nothings to Glastonbury’s Michael Eavis, who betrayed him by revealing his “secret promise” to scrap Trident; he says another thing to the press: the careful, Milne-shaped, sneaky prose; and he’s interpreted as having said yet another by those who look on in expedient awe, but don’t actually hear him.

He’s a politician. He’s a fudger. He’s a man who was selected to lead his party partly on the basis that having any principles – no matter what – is better than having none. He’s a man who was selected because he doesn’t U-turn. Yet, over this, over Brexit, over more, he’s turned out to be the quintessential worker – of the room. That’s not to deny that his campaign, and many of his policies, proved understandably appealing to well-meaning voters from all corners of the left-wing base.

But he got lucky facing opponents who wouldn’t, or couldn’t argue him down. And there’s a difference between making idealistic arguments to small halls full of people who agree with you, and making nuanced difficult ones when the weight of the country is upon you – and the ears of the world are listening. Yes, he can do both, but which do his followers really want? Which is he leading them to believe they should?

When you fear that your enemies might want blow you and the collateral rest of humanity off the face of the earth, it’s long been argued that the best tactic is to appear willing to do the same. Sure, in these days of modern terrorism, you can’t always know if your enemy will care; sure, times change to the extent that Twitter rebukes may soon become a standard feature of nuclear brinkmanship; but the emergence of new threats does not necessarily obviate the old.

None of this is a game, yet sometimes to stay in the game is the hardest game of all. And none of this is simple – except to know it’s wrong to suggest that Corbyn is the sole politician in Britain who doesn’t “want to kill millions of people”. How have we got to the point at which this has to be said? How badly have his opponents presented themselves?

Again, we need to revisit the old arguments. And we need to listen to those best placed to make them. This column does not offer a complete case for deterrence. Rather, it’s a reminder that we need clear arguments for the positions we claim to hold, and against those we don’t. This is important not only because without arguments we are weak in the face of our adversaries, but also because we must keep checking that we’re right.