Nothing in politics is what it seems. False assumptions take hold through constant repetition, blowing away the more complicated evidence in front of our eyes. Here are a couple of small examples of misplaced orthodoxy, before I move on to the case of Ed Miliband. For months before the last election, I read or heard several times a day that the Conservatives were heading for a decent majority. It was not an assertion, but an assumption on which a thousand columns, blogs, tweets and broadcasts were based. Yet nearly all the polls at the time pointed to a hung parliament. Misplaced assumptions swept aside the awkward evidence.

Similarly, I hear or read all the time that the Chancellor, George Osborne, is a brilliant strategist. Again this is not an assertion, but an assumption on which to develop further arguments, such as the suggestion that Alex Salmond has met his match. No doubt Osborne is quite good as a wily strategist or else Cameron would not allow him to hold sway, but is there evidence that he is as formidable as assumed? He was William Hague's main adviser up to the 2001 election, was consulted by Michael Howard before 2005, and was pivotal in 2010. The Conservatives were slaughtered in two and did not win an overall majority in the third. Currently, Osborne's economic policy is not exactly going according to plan. Perhaps we should question assumptions held with casual rigidity.

From the chorus of Miliband-baiting, I hear or read that he is too clever, not clever enough, has no ideas beyond fratricide, has ideas that are fatally left wing, and policies that are all over the place. An assumption is taking hold once more, so much so that when YouGov released its latest poll, the headline mistakenly declared the Conservatives were ahead when Labour was. A vivid example of the evidence getting in the way of the orthodox narrative.

Labour should be doing better in the polls, but it is not doing as badly as the chorus implies in its hand-wringing disdain. The reason for its mediocre ratings is multi-layered and not just about Miliband's leadership, although, of course, this is a factor. At this stage in a parliament, an opposition's standing is determined largely by how the government is perceived. During Cameron's early leadership, the Blair-Brown divide was reaching its tense bizarre climax, a dream context for a new opposition leader to make his mark. Miliband takes over when selectively one-sided memories of the last Labour government are still fresh and when a coalition is young, a tougher context.

In terms of policy, Miliband stands comparison with Cameron. Cameron's big idea, the Big Society, was only unveiled a few months before the election at his Hugo Young Lecture. There had been earlier attempts at definition, but they fell away. As for economic policy, from a flat tax, to supporting Labour's spending plans, to proposing cuts, Cameron navigated many U-turns. On the whole, though, the chorus worked on the uncritical assumption that Cameron as opposition leader was a coherent moderniser. Yet the vilified Miliband's moral capitalism, outlined in his conference speech, is as close to a developed theme as anything Cameron espoused at the equivalent point in his leadership and one, if fleshed out credibly, with more populist potential.

As the abuse has grown, Miliband passes a test of leadership. He has kept calm. I am sure this is partly an act, but not entirely. He was close to the centre of power for more than a decade. As an ally of Gordon Brown, he witnessed and participated in endless seemingly momentous ups and downs that, in the end, did not matter very much. He was more distant from the heat of power than Ed Balls, but both know the dangers of being eaten by frustrated ambition and descending into gloom because of orthodoxies proclaimed by the chorus.

They have far more political experience than most facing the ordeal of opposition. It gives them perspective, a powerful weapon. On Saturday, Balls delivered a speech that placed his own record in context, linking his policies now to his robust views in the 1990s on the ERM, the Bank of England's independence and public spending – so robust that the normally perceptive David Blunkett told me at the time, wrongly, that Balls was a "bloody monetarist".

Now another assumption takes hold, that Balls is a reckless public spender compared with those who worshipped at the altar of Tony Blair. This is a myth. The intense rows between Blairites and Brownites in government were over public service reform, the euro and Blair's method of seeking wider support by always "taking on" his weak party. On the level of public spending, there was much agreement, though less on how it should be spent. None of this means Miliband is wholly secure or strides towards inevitable victory, but beware false assumptions, wilfully or inadvertently held, that shape and distort the current political situation.

s.richards@independent.co.uk

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