Bruce Anderson: Right-wing pundits should stop the belly-aching and let Cameron get on with a very difficult job

The wisest Tory aphorism was minted by Lord Falkland: "When it is not necessary to change, it is necessary not to change". That does leave open the question of how to tell when change is necessary, but even so. The silver medal goes to an Irishism, which is also the best guide to the recent history of the Irish economy. "Ah well, this pig doesn't weigh as much as I thought it did - but then again, I never thought it would". Realism mitigated by humour is the ideal Tory combination. The opposite, far too common at the moment, is fantasy solutions expounded in belly-aching language.

Even some normally sensible MPs and columnists are in danger of losing contact with reality. They are talking or as if there were obvious solutions to Europe and to economic growth: as if it were mere languour or timidity which was preventing Messrs Cameron and Osborne from showing leadership and putting things right. The word "dithering" has been used: an absurd charge. So let us look behind the sillier rhetoric to see whether the critics' case has any basis in reality.

On the economy, they assert the need for tax cuts. That might not seem contentious: every sensible Tory is a Lafferite. We should all believe in cutting taxes, when it is safe to do so - and to be fair to the belly-achers, we are not dealing with impenitent Keynesians. They are concerned about the deficit, but they want to inject more demand into the economy by cutting taxes, while covering the cost with further cuts in public spending.

There are two problems with that. First, there is no reason to believe that it is good economics. You do not have to be a Keynesian to recognise that public spending creates demand. So there is no guarantee that there would be any net increase in demand from a tax cut financed by a spending cut, even if the relief were directed at the lower paid, who have a higher propensity to spend. Other factors would come into play. The message would be received that the government had an open-ended policy of job reductions in the public sector: a tax cut next month, your P45 the month after that. So even among many of the lower-paid, there might be the temptation to save rather than spend. In that case, the double-cuts strategy could even lead to a net fall in demand.

Second, there is every reason to believe that it is lousy politics. All governments depend on consent, as even the Eurozone will come to recognise. In the UK, further spending cuts could jeopardise that consent. A lot of voters think that they know who is to blame: the bankers in particular and the rich in general. That is nonsense. The bankers did not invent the Euro. They did assume that economic growth would sail merrily on; so did almost everyone else. As for the bonuses, they are trivial in comparison with the liabilities which the founders of the Euro have created.

Yet nonsense can be potent. If the government did what the belly-achers are advocating, the public mood would be implacably hostile. There is a left-wing protest group called Un-cut: not to be taken seriously. But if the government took the belly-achers' advice, Un-cut could become more popular than double-cut. The coalition would almost certainly break up. My friend Iain Martin, who might not agree with everything in this article, has been known to trade in belly-ache futures. He also founded the "Do not underestimate Ed Milliband society". A few months ago, it filed for intellectual bankruptcy. It may be that the double-cut proposal is just a cunning ploy by Iain to rescue it from the receivers (its current valuation is one penny in the Pound: offered, not bid). Tory commentators should not be offering mouth-to-mouth resucitation to a stricken Millipede.

The belly-achers have one excuse for their skewed judgment - but it is a further reason for distrusting them. They have not forgiven David Cameron for failing to win the last election outright. At the time, most Tories were disappointed, and everyone has their favourite explanation. Mine, briefly, is as follows. From 1974 onwards, in voting percentage terms, the Tory party has done very badly: always failing to realise its demographic potential. This is because it is seen as the party for the rich: people who do not have to worry about their bills, or about conditions in the local schools and hospitals: they would never dream of using them. David Cameron tried to put that right, and always out-polled his party. But in 2010, people were worried. A lot of them were still not ready to trust the Tories. If they wanted a fresh-faced alternative to Gordon Brown, there was always nice Nick Clegg. It must also be remembered that the full horrors of the Brown regime had still been concealed from the general public, who did not know that in comparison to his Downing Street, Macbeth on the battlements of Dunsinane was a sylvan idyll.

In response to such an account of Mr Cameron's electoral difficulties, some of the belly-achers become positively Bennite. David Cameron lost because he was not offering proper Toryism. He should have campaigned on scrapping the 50p rate and no ring-fencing for the NHS. If that had been the Tory platform, it is just possible that Gordon Brown might still be Prime Minister.

We are not finding much in the way of realism, and there is even less to come on Europe. The PM's detractors have a simple case. The Euro could never have worked and is now in a well-deserved mess. Europe's crisis is the UK's opportunity. So let us have a brisk re-negotiation. We want a Common Market plus inter-governmental co-operation. If that is not on offer, we are off, and as we are running a trade deficit with you, you would be mad to retaliate.

If they were thinking purely with their emotions, well over ninety per-cent of Tories would agree with that. But emotion is not enough. That argument makes one wholly-unjustified claim. It rests on the assumption that those who are running the Euro are not mad. But if the cement which bound the Euro-zone had not contained a large admixture of insanity, we would not be where we are.

It would be dangerous to assume that sanity could easily assert itself and that we could continue to enjoy free trade with a resentful, unstable Eurozone, full of social unrest: full of recession, if not indeed depression. Free trade is an unrivalled creator of wealth. But free trade comes naturally to stable and confident societies. When confidence evaporates and stability is menaced, open trade will come under threat. We all know about Smoot-Hawley and the follies of the Thirties. Given the modern history of mankind, who could possibly assume that those follies would not be repeated?

Nigel Lawson thinks that it would be bad for Britain if the Euro were to collapse, and worse if it staggered on. For what little it is worth, I agree with him. But that is not an argument for renouncing diplomacy. Your neighbour's house is on fire. You feel like saying: "Serves you right. It's hideously ugly and you could never have afforded it anyway. What's the point of calling out the fire brigade? Let it burn down; you can go and sleep at Charing Cross, under the arches". So do you indulge your feelings? No: not if half your trade is with that neighbour. Assuming that you want to preserve that trade, you strain every face-muscle to look sympathetic.

That is what the PM and the Chancellor have been doing, and they deserve a sophisticated understanding from their own party. This is not a Euro-plot: the threat from a federal Europe is now over. It has instantly been replaced, by the threat from a failing Europe. We will be able to re-negotiate if we choose our moment and our tactics. If that re-negotiation were to fail, divorce would be an option, but let us ensure that it is an amicable divorce, not a further lurch into a Continent-wide slump. Messrs Cameron, Hague and Osborne have a daunting task, with no certainty of success: awesome responsibilities, which they cannot delegate. In such circumstances, any Tory worthy of the name should know how to respond: with realism and loyalty.