Much has been made of the folly of Labour tearing itself apart over Trident in 2016. The argument has often been put, usually by Labour MPs who support Trident renewal, that the row is both a distraction from the issues that really matter and futile, as the project will be beyond the point of no return before the next election.
The counter-argument is made on both practical and ethical grounds, and demands that Labour should adopt a morally defensible position whatever the political circumstances of the day. Either nuclear weapons are right or they are not.
Neither position is consistent with any kind of fudge. Trident has become a binary issue that defines whether you support Jeremy Corbyn's new politics, with its claim to be based on principle over pragmatism, or you don't.
This is both fatuous and, more damagingly, a gratuitous gift to the Tories.
For anyone with doubts about Trident, the argument should not be 'who's side are you on?' but 'how do you make a change in Britain's defence posture a realistic possibility?' If you're genuinely interested in what best defends our nation, rather than simply what's morally defensible, you can and should be both anti-Trident and anti-Corbyn.
I would place myself on the extreme sceptic wing of the Trident debate. Along with many former military leaders and ex-Cabinet ministers, I find the strategic case for Trident implausible and the cost massively out of proportion for the diplomatic clout it supposedly brings. As a student I marched with CND. As BBC radio's Defence Correspondent in the mid-eighties I enjoyed pressing Margaret Thatcher on why she thought nuclear weapons defended Britain. If the case was weak then it is far weaker today.
If I could click my fingers now and turn Britain into a non-nuclear state with a settled foreign policy based on the pursuit of conflict resolution rather than sabre rattling I would do it. That should make me a natural ally of the current leader of the Labour party, but it does not.
I say that not simply on the assumption that he's going to lose anyway thus making his idealism impotent, although that argument has some merit. It is rather to point out the simple logic that supporting Jeremy Corbyn's wish to see Labour revert to a policy of unilateralism will make the full deployment of the Trident successor weapons system more likely not less. Indeed, it will make it a certainty.
If Labour heads to the polls in 2020 with a unilateralist defence policy and a leader who makes it clear he would never use the deterrent while he was prime minister, that election would inevitably become a referendum on whether Britain should remain a nuclear power. Just as inevitably Labour would not just lose, but lose massively. We've tried it before, in 1983 and 1987, under leaders who were a lot more popular then than Mr Corbyn is now.
Even if every Trident opponent, including all those generals and defence experts, threw their weight behind it, which clearly wouldn't happen, the 'Retain' campaign would win.
Call me defeatist if you like, but I'm no fan of suicide missions. Labour would lose seats on an industrial scale. Any hope of winning in 2025 would evaporate. The Tories would be in until 2030 if not longer. Trident renewal would go ahead, the new Successor class submarines would be at sea and fully operational and keeping a Rolls Royce deterrent, with all the costs involved, would become the settled policy of the United Kingdom.
Let's enter fantasy land for just a moment and imagine that Labour could down-play the nuclear argument in 2020 and win a majority based on our policies on housing, investment, economic regeneration and all the rest of it. A Labour Defence Secretary would then apply the brake to Trident renewal and best he or she could by that stage. What then? Labour would have to win every subsequent election to stop the Tories coming back and rearming the warheads.
On defence, as on so much else, the only progressive reform worth the name is reform that sticks. Legislation that changes the debate and persuades your opponents to keep it in place is legislation worth passing. Devolution, overseas aid, the NHS, LGBT equality - we've shown it can be done.
A Labour government committed to supporting Trident only as long as there is a sufficient consensus that it adds to our national security, coupled with a serious re-evaluation in office of our strategic role in the world, would be infinitely preferable to a crushing if valiant defeat.
There are many Tory sceptics on Trident, just as there are Tory republicans and Tories who favour the decriminalisation of drugs. They are content to accept that their views are not, for now, supported by a majority in Britain. They don't change their opinions, which are sincerely held, but nor do they ask their party to adopt them as official policy and scream them from the rooftops. It doesn't make us Tories - no really, it does not - to recognise that sometimes that is the least-bad option for us too.