The rise of Corbyn has been remarkably rapid. Bookies only started placing him as the favourite in late July. In the immediate aftermath of the general election, back when Chuka Umunna was news, a consensus began to develop that Labour had lost because Ed Miliband had failed to engage with aspirational voters. This expanation had the merit of being supported by evidence from post-election focus groups.
So we might say that Labour could have taken a different course. It could have asked itself why over 15 million people voted for right-wing parties (the Conservatives and UKIP), why Ed Miliband had screwed up, and what a social democratic party is for in a modern western society. But that's all over now. It looks very much like the party faithful, and their penumbra of left-wing supporters, have succumbed to the appeal of the comfort zone.
The fear is that the ghosts of the 1980s are rising out of their graves. If this is true, we know what's going to happen next because we've been here before. Back in 1979, Labour's defeat was followed by a civil war, dominated by two dramatic struggles. There was Tony Benn's insurgency of 1980-81. The premise of the Bennites was that the voters had put Margaret Thatcher in power because they wanted a stronger version of socialism. The second struggle was the campaign against the Militant Tendency, which came to a head in 1985. Militant was an openly communist group which was so extreme that its members regarded Benn as a moderate (they nicknamed him "Kerensky"). Meanwhile, of course, the Tories were racking up enormous majorities at the polls. Corbyn's enemies are quick to point out that he was up to his neck in this stuff. He was a card-carrying Bennite back in the day, and Militant's direct successors, the Socialist Party, have played a significant role in campaigning for him.
They also point out that the Conservative Party wouldn't have made this mistake. It is difficult to imagine Tory MPs amicably "lending" their votes to get someone like Gerald Howarth or Edward Leigh onto the ballot in order to "widen the debate". When IDS slipped through the net in 2001, he was rapidly defenestrated when it became clear that he was going to lose the next election. For all their adulation of Churchill and Thatcher, the Tories are remarkably unsentimental when it comes to their leaders. They know that their party exists to win elections, as do all political parties.
It's partly Tony Blair's fault, of course. New Labour's domination of the Labour Party was always an authoritarian, top-down project. Blair focused on winning elections rather than on winning the hearts and minds of the comrades. A lot of his public support came from conspicuously distancing himself from the traditional Labour movement. Once the Blairs, Campbells and Mandelsons left the stage, the Blairite right was too weak to prevent the party from slipping out of its grasp. Iraq didn't help either, of course. This is why David Miliband is presently running a humanitarian think-tank in New York City rather than deciding whether to bomb ISIS.
There is, however, an alternative scenario. Corbyn may be hardline, but he's not stupid, and he didn't come down in the last shower. He has served under every Labour leader since Harold Wilson. As his support grew over the summer, he clearly started viewing his candidacy as more than a token keep-the-red-flag-flying endeavour in the great tradition of John McDonnell and Diane Abbott. He has consciously been positioning himself as a moderate. While his more bovine supporters have chosen to become offended at the very idea of trying to win elections, he has realised that he can't allow himself to be painted in the minds of the voters as a Trotskyite retread. He may well succeed in wrong-footing the cruder attacks from the Conservatives (and Rupert Murdoch) attempting to link him to the IRA and Hamas.
And Corbyn does have a potential constituency outside the Labour faithful, if only he can tap into it. His unspun, man-of-the-people approach may well impress voters. His populist economics might appeal to Ukip supporters. This is the Ken Livingstone option - an old lefty reinvents himself as a popular mainstream figure. Maybe Labour needs to get over the neurosis of thinking that it's permanently 1983. Maybe the new £3 supporters are right to ignore the minutiae of what Corbyn got up to with Tony Benn back when Frankie Goes to Hollywood was in the charts.
Of course, governments generally lose elections rather than oppositions winning them. How Corbyn fares is going to depend to a large extent on circumstances beyond his control. If the economy slows down over the next few years, the EU referendum goes badly for the Conservative Party, and the incumbent Prime Minister turns out to be the Rt Hon Sir Gideon George Osborne, Bt - if this is how things go, the 2020 election might be a closer run thing than most people currently expect.
There is something else that Corbyn needs to bear in mind. He is not a young man. At 66 years old, he is going to fight one general election at the most. His most important task is to ensure that there is a good choice of leadership candidates when the post falls vacant again - something which Blair had no interest in doing and which Brown actively tried to prevent. Pay attenion to who gets the main Shadow Cabinet jobs, and indeed the not-so-main ones. All eyes are on Corbyn at the moment, but his appointments are going to matter a lot more in the long run.