POLITICAL parties recently evicted from government, and headed by a new leader, should take the opportunity to admit past failings. Many in Westminster, including myself, expected the Labour Party to have by now acknowledged, and apologised for, the standout failing of its time in office: allowing public spending to run out of control in the years before the financial crisis. After the longest economic expansion in British history, the government should not have still been borrowing to spend. Instead of going into the recession with a warchest, it went in with a deficit. Recognise this error, say sorry, take the hit, and move on, would seem to be the intellectually honest and politically canny thing to do.

Instead, Ed Miliband has manouvered his party into a bizarre and extremely unpromising position. In recent op-eds, yesterday's speech to the Fabian Society conference, and today's appearance on the BBC, he has rejected the notion that Labour overspent. The 2.4% deficit the government was running would have been fine, he says, were it not for the banking crisis, which caused tax revenues to evaporate while requiring massive amounts to be spent on bailouts and fiscal stimuli. In other words, if only economic growth were endless, if only recessions did not happen, if only this pesky "economic cycle" thing would go away, governments could spend freely and perpetually. As many commentators have noted, this is grimly redolent of Gordon Brown's insistence that "boom and bust" is something that can be transcended, rather than a cold reality that governments must make preparations and provisions for.

And in a pretty transparent attempt at deflection, Mr Miliband is effusively apologetic for almost every other vaguely regrettable thing that happened in Britain between 1997 and 2010. He is sorry for failing to properly regulate the banks. He is sorry for allowing the financial sector to become too big a part of the British economy. He is sorry for relying on redistribution to fight inequality, instead of somehow prodding the private sector to narrow wage differentials in the first place. He is sorry for playing fast and loose with civil liberties. He is sorry for not being green enough. He is sorry for being "too technocratic and managerial" and for the "target culture". I haven't checked, but he may have said sorry for the creative decline of Oasis after their second album. Anything, it seems, to avoid admitting that Labour took an irrationally exuberant approach to the public finances, at least for a few years.

Labour's political thinking here is that the battle over the past must be won in order for the party to stand a chance in the future. Only by persuading the public that they are wrong to regard Labour's record of fiscal management as disastrous (and the party's internal polling says that is indeed what voters think) will they win back credibility.

This is badly, badly wrong. One of the iron rules of politics is that no opposition ever persuades the public to change their minds about anything. Only governments, or external events, can do that. Oppositions must recognise where the centre-ground is, occupy it to get elected, and then move it in their direction when they are in power. William Hague, Iain Duncan Smith and Michael Howard are among those who can tell Mr Miliband what happens when opposition leaders ignore that rule.

As long as voters are being told that they are wrong to think what they think about Labour's record, the party will not get a hearing from them and its poll-ratings on the question of economic competence will remain poor. And Labour may spend years bogged down in this campaign to evade blame for the fiscal crisis before they realise its futility. This is time they could be spending on building a policy alternative to the government, on gradually and painstakingly fixing the Labour brand, on doing some intellectual heavy-lifting on questions of first principle such as what the centre-left is for in an era of no money.

That there is no political logic in Labour's denial of culpability for the deficit suggests something even more worrying, something that is confirmed in private conversations with many of the party's MPs and advisers: they actually believe it.