Back in May, we all agreed that Labour should enter a perhaps lengthy period of reflection in order to recover its sense of purpose and become once more the electoral force it needs to be. The last thing we needed was a leadership election.
And sure enough, almost immediately the deep and wide debate that was so urgent was displaced by the narrow manoeuvring of the three frontrunners - and, three months on, their failure to think big or even distinguishable ideas has left the field open to the outsider who can.
Jeremy Corbyn isn't saying anything he hasn't been arguing, largely unheeded, for the 32 years he has been a backbencher. But he appeals not just to convinced left-wingers but also to party members who may in the past have disapproved of his serial disloyalty and despaired of some of the causes he's espoused but are now stirred by an obvious sense of conviction and purpose they can't find in any other candidate.
It's Corbyn's lack of pragmatism that makes him both attractive as a candidate and unelectable as a leader. But - at least for another month - he is not Labour's principal problem. His success lies in the failure not just of the three frontbench contenders but of the breadth of 'mainstream' Labour to offer hope that it can renew its mission, inspire its supporters and, ultimately, win over the electorate in 2020.
The Battle of Ideas - No Contest
Corbyn is winning the battle of ideas by default. He has a programme. He strikes a chord with many of those both within and outside the Labour party who believe that politics really does have a purpose and that through the choices we make and our ability to persuade others that they are right, we really can create a different and better society.
The others offer no alternative. What has become of mainstream Labour? Where is its idealism? Where are its ideas?
Nowhere is the frontbenchers' failure to think imaginatively and debate honestly more apparent than in the mantra with which they collectively hobbled themselves even before Corbyn had thrown his hat in the ring - namely that Labour must now become the preeminent party of aspiration, aspiration, aspiration.
But what precisely is this aspiration? Is it a value? Is it an aim? Or is it just an aspiration? Are some aspirations - for example for social justice rather than personal advantage - better than others? Are some aspirations out of bounds - for example those of the city speculator or the militant fundamentalist? And what are we to do when one aspiration conflicts with another - for example the quest for limitless consumption with the commitment to a more sustainable planet?
In one of his campaign videos, Andy Burnham explains that aspiration is "about giving every single person the dream of a better life". Is that really what he means? This is the kind of aspiration which drives the US economy and makes America one of the wealthiest but also one of the most unequal and divided societies. Is that mainstream Labour's vision for our society?
And what is new about this aspirational agenda? Labour's pledge to create "a country where the next generation can do better than the last" was so central to our election campaign that it was literally carved in stone. We need less not more of this vacuity.
But at a time when they should be painstakingly challenging all the assumptions on which we fought the election, the three frontbenchers seem simply to have concluded that Labour's sloganising didn't go far enough. We weren't sufficiently 'passionate' about 'real' people, the hard-working, tax-paying, home-owning, law-abiding, immigrant-fearing, Miliband-despising, aspirational English who ended up voting for the Conservatives and UKIP - or the Scots who were already having such difficulty in differentiating between the two main parties that they turned to the SNP.
Where are the values and the ideas which 20 years ago secured the often enthusiastic support of those who have in the last five defected in such numbers to both the right and the left?
Winning the Argument
How can Labour hope to persuade the electorate if it cannot convince itself of its own worth? Despite our defeat, despite the need for the humility the mainstream candidates have been endlessly parading, we should also be proud of our achievements; we should be eager to remind the electorate of how within recent memory a Labour government made their lives better.
There are many in party who have always been more comfortable in opposition than in power, who will always remember Tony Blair for the Iraq war but not for Labour's investment in health and education - or the minimum wage or tax credits or SureStart or the crusade against child poverty or civil partnerships or the Disability Discrimination Act or the Human Rights Act and so much more. Many of them see redemption in Jeremy Corbyn. But Labour will not truly rediscover itself until it is able to celebrate its successes as well as acknowledge its failures and, frankly, until it has learned to rehabilitate the prime minister who presided over the achievements as well as the mistakes of three successive Labour administrations.
Mainstream Labour needs to recover sufficient self-confidence to be able to lead as well as follow opinion. Of course we should be listening and understanding. But if that's all we're doing, what makes Labour distinguishable from the other parties? What becomes of our defining principles and our political purpose?
Jeremy Corbyn has always been prepared to show this kind of leadership. Very few have followed and, were he to become Labour leader, very few will. But where is the confidence and courage of the other candidates to take issue with popular opinion when they want to change it?
Of course that is challenging: it means that Labour will not always be as comfortably in step with public opinion as we would like to be. It may even mean that we will have to be prepared to lose elections until we win arguments. But that is not a justification for losing elections as Jeremy Corbyn undoubtedly would but the case for mainstream Labour to go out and win the arguments for communities as well as individuals, for equity as well as enterprise, for public services as well as business, for internationalism as well as our narrower national interests.
Mainstream Labour has a choice - though not for much longer if Jeremy Corbyn wins: it can either trim its sails, keep its head down and wait for the Conservatives to cede power as they periodically do when they are spent or divided or both.
Or it can recognise why Corbyn's appeal is so strong, rediscover confidence in Labour values and set out to crusade for the hearts and minds of the electorate on the basis of real but realisable hope. By all means let's embrace aspiration but let there be inspiration too. Idealism may be unfashionable in a cynical and materialistic age but it is a necessary feature of all worthwhile politics.
It is crucial that over the coming month at least one of the mainstream candidates rises to that challenge. As things stand, I only know the candidate I can't support and that is not enough.