John Rentoul: Gordon Brown asks to be judged on his long-term decisions. So here goes...

Are we coming, or going? And I don't just mean Gordon Brown. They are all at it, promising affordable housing. Except that the moment the global credit crunch starts to deliver it, they say it's a bad thing and the Prime Minister gets the bankers round to No 10 for a meeting that is not a crisis meeting to work out how they can prop up house prices again. And now he's in New York to convene another meeting on Wall Street that was not a crisis meeting, to discuss how to make housing less affordable.

Brown asks us to judge him not on the tittle-tattle but on the long-term decisions. Fine. It does not matter whether he refused to touch the Olympic torch as a gesture of solidarity with the Tibetans, or whether he had never had any intention of touching the torch and it just looked as if Chinese secret agents in blue shell suits with radio earpieces wrestled it away as he was about to hold it aloft. He is right that it should not affect our view of him that, not yet 10 months in the job, he has to deny that he is thinking of quitting. He was "starting a job that I mean to continue", he said, in one of at least three long interviews before he set off to America.

What would he say to Labour MPs who think he should stand down, Brown was asked. "I would say that I'm the person who set the Labour party off on the course of making long-term decisions for the future." He has a point. We should not judge him on whether he flies to the States in a rented plane run by some airline no one has heard of. Some of my colleagues in the press pack accompanying the Prime Minister talked nostalgically of flying to New York with Tony Blair on Concorde and a little dreamily of the plan, now squashed by Brown, for a "Blair Force One". (When Brown squashed it last month he was hailed as a new Stafford Cripps: austere, unflashy, careful with the people's money – ah, for the joys of article 94 of the European Convention of Human Rights, the right of a free press to be utterly inconsistent.)

Nor should we judge him on the basis put forward yesterday by Brian Wilson, the former MP and minister, who said: "There is a danger of Gordon Brown becoming the Donald Crowhurst of the political world." Crowhurst, Wilson reminded us, was the yachtsman who was so desperate to win a round-the-world race in 1969 that he reported false positions and faked his log book while sailing around the Atlantic. "It was only when it looked like he was going to win that the extent of the deception was exposed." Well, it is a more inventive analogy than the Wizard of Oz, adopted by Matthew Parris and Polly Toynbee, but it is beside the point.

We should judge Brown, as he says, on whether he will take "the right long-term decisions for the future". Only for some reason we can't remember any, except a long-term decision that Brown did not mention in his pre-flight videos. The abolition of the 10p-in-the-pound starting rate of income tax was incontrovertibly his, and definitely rather long-term: a decision that was announced more than a year ago but only implemented last week.

And when Brown lists the sort of decisions he expects to be judged by, we wonder whether it might be more flattering to him to judge him by his ability to turn up at treaty signings on time. In his Sky News interview he listed examples of his long-term decisions: a new generation of nuclear power stations, binding climate change targets and planning three million more houses.

On the first, you will have to excuse a Blairite ultra for passing. (Blairite ultra, by the way, will no doubt appear in dictionaries next year, defined as "originally, a term denoting any British citizen of voting age who does not regard Tony Blair as a war criminal; now, vulg, term of abuse used by Brownites, qv, to denounce people saying 'I told you so' to Sunday newspaper journalists".) My memory is that it was Brown's predecessor who took the heat on that decision, giving a speech to the CBI in a side room of its conference centre when Greenpeace took to the rafters.

On the second, we are still waiting for further and better particulars. The principle of binding targets for greenhouse gas emissions is a vitally important one, and it would be churlish to point out that the approximate order by which British politicians came to accepting it was: David Cameron, David Miliband, Gordon Brown. But it is still just a principle, until the policies are devised to deliver it. So far, we have had low-energy light bulbs and a suggestion that the Government might do something about plastic carrier bags by 2075.

Then there is affordable housing. Build more houses to reduce prices, Brown said, before the credit crisis that is not a crisis intervened. But now that prices are falling anyway, he still says that this is one of the long-term decisions on which he must be judged. As if we have learnt nothing from the failure of a "predict and provide" policy towards roads and runways. This means observing that traffic is increasing, and building more roads and runways to allow it to flow more freely. Only all that happens is that the new roads and runways fill up with more traffic that is created because those extra journeys are now possible.

We began to realise that "predict and provide" doesn't work for roads more than a decade ago. We may be on the cusp of recognising it doesn't work for air travel – the third runway at Heathrow could be the turning point. On the basis of my conversations with senior Conservatives, I think it is still possible that David Cameron may eventually oppose the third runway.

But when it comes to house-building, the politicians generally have not got to stage one. Build more houses, and people will come to live in them. We live in a rich part of a single market that allows free movement of labour.

The only thing that saves Brown from ridicule is that the Conservatives are just as bad. Even Boris Johnson promises affordable housing for the people of London, which is even less achievable – without a return to the whole apparatus of municipal government telling people where to live – because if we have free movement in the European Union, we have even freer movement in the United Kingdom.

Yes, of course, Brown's clunking presentation skills are not the real issue. It can even raise an indulgent smile when he so utterly mangles the line-to-take given to him by his principal adviser, Stephen Carter, as he did on Monday: "Every effort of mine, every day that I wake up is about keeping this economy moving forward." Waking up every day is a big part of Brown's message. He woke up again yesterday, on ABC's Good Morning America: "Every day you wake up and you know there's going to be a new challenge." (Not that sort of challenge, Miliband, Balls and Hutton, prefects tittering at the back.)

It matters much more that Brown promises what he cannot deliver. He calls these impossible promises "long-term decisions". Affordable housing? He might as well promise affordable money.

John Rentoul is chief political commentator for The Independent on Sunday