Anyone who supported Ed Miliband in the Labour leadership contest and afterwards will find it hard, even now, to admit to their error. Rare will be the commentator who asks him or herself whether it’s possible they were wrong about everything all along.

These are perfect conditions for cognitive dissonance, which occurs when the brain attempts to accommodate fiercely held prior beliefs with contradictory new information. Self-delusions will bloom like daffodils in Spring.

In order to get through the coming symphony of spurious rationalisations it might help if you take a drink – I suggest something non-alcoholic if you want to avoid liver failure – every time you hear one of these explanations for Labour’s defeat:

1. THE MEDIA DID IT

No left-wing account of this defeat will be complete without a reference to the Tory press (bonus drink for “Murdoch-controlled”) and its supposed inexorable hold over the political psyche of the nation. Funny: the day before the election everyone decided The Sun was a joke and nobody reads newspapers anyway.

2. THE ESTABLISHMENT STITCHED IT UP

Obviously related to (1). but with a wider scope. The forces said to be ranged against a Labour victory will be described as powerful and subterranean. They will include bankers.

3. CLEVER TORIES

It will be said that the Tories, in their ruthlessly efficient way, pinned the blame for austerity on Labour and Labour allowed it to stick. Clever Tories. Few will mention that the Tories were, for the most part, a hubristic and directionless shambles, divided amongst themselves, the authors of several howlingly stupid own goals that would certainly have sunk them had they not got so lucky with their opponent.

4. VOTERS ARE STUPID AND VENAL

You will hear much wailing about the selfishness of voters, their hard hearts and closed minds. This tweet from Hari Kunzru expresses the contempt for ordinary people that eats away at the soul of many a bien penseur:

5. THE SNP STOLE OUR VICTORY

It is true that nobody, but nobody, foresaw the SNP tidal wave. But it’s not true that Labour would have won or even done OK without it. Labour saw a net gain of one seat from the Tories in England. One. Seat. One seat, in an election where everything favoured them. One seat, after five years of a shabby and meretricious government making unpopular decisions and a third party that virtually donated its voters to them. An epic failure.

6. LABOUR WASN’T LEFT WING ENOUGH

Many of your drinks will be prompted by variations on this perennial theme. Labour accepted the austerity narrative. Labour weren’t green enough. Labour weren’t radical (which has somehow come to be used as a synonym for left-wing). Given that the last time Labour won an election without Tony Blair was 1974 it’s hard to believe people still think the answer is to move left. But people still do. I sort of love these people for their stubbornness. But I don’t want them picking the next leader.

7. TONY BLAIR

Rule number one of left-wingery: it is always, somehow, Tony Blair’s fault.

8. POLITICS IS TOO SUPERFICIAL

This seems to have been Ed Miliband’s understanding of the problem. He made a speech last summer in which he bemoaned the primacy of image in modern politics. Then last Sunday he stood for the cameras in front of a giant limestone monolith. So perhaps he’s ambivalent. But undoubtedly we’ll hear his supporters declare sadly that we live in shallow times. A man can’t even talk about pre-distribution any more without being pilloried. This one is essentially a variation on (4).

9. ED WAS THE WRONG MESSENGER

This explanation will be expressed with ruefulness and come garlanded with references to the former leader’s decency and integrity and intellect. The thing is, they’ll say, he really wasn’t suited to TV (refer to (8) here). In person, my God, it was like Elvis was in the room. Now, this is a tricky one to stand by because the day before the election everyone agreed that Ed being weird wasn’t a problem any more. People who cling to this reason are committing the very sin of which they accuse the voters and media. Labour lost (mainly) because of the message, not the messenger.

10. ANTI-POLITICS

Ed Miliband somehow ran smack into a wave of anti-political sentiment that David Cameron somehow managed to sidestep. Mystical visions of a new kind of politics rooted in the real lives of working-class people will abound.

The non-delusional explanation is simple. It was proffered, some time before 7 May, by a former Labour leader. When a traditional left-wing party competes with a traditional right-wing party, you get a traditional result.