Big-willy politics is back. If we do not build a third runway at Heathrow, says Tory MP Tim Yeo, Britain will "slide towards insignificance". Britain will leave the premier league, lose out to China and become a second-rate power. Those who refuse to build third runways are mice not men. As for manifesto pledges and coalition agreements, they are for wimps. Real men love planes. To be great, says Hamlet, is "greatly to find quarrel in a straw when honour's at the stake". What greater honour could there be than a third runway at Heathrow?

Similar dire warnings were made if Britain withdrew from "east of Suez", refused to join the euro or failed to back a British car industry. They are why governments still build aircraft carriers, buy nuclear missiles and fight foreign wars. They are why lobbyists argue for banking bonuses, high-speed trains and lofty skyscrapers. Yeo says we risk repeating Macmillan's retreat from empire. Foreigners will kick sand in our faces and be rude about our food and our women.

Big-willy politics is the most dangerous politics of all. It appeals to paranoid machismo, not argument or reason. Yeo's taunt at David Cameron – is he "a man or a mouse" over Heathrow – is the dumbed-down remark of a politician who takes £140,000 in a year from energy companies while chairing the Commons energy select committee – though this may say more about today's parliament than about Yeo. The thesis that any profit to an interest group must be "good for Britain" is insidious. War is more profitable than peace, but we do not go to war with Russia.

The case for a third runway at Heathrow is like that for a heliport in St James's Park or a shard on Hampstead Heath. Some might find it remunerative and convenient, but we try not to commit such outrages on the environment these days. No sensible country builds airports with flight paths over densely populated areas. However much BAA and BA may spend on PR to keep alive "the case for a third runway", it cannot alter this fact.

The London area has more airports and more runways than any other city in Europe. Heathrow alone serves more "key business" destinations than Paris and Frankfurt together. Screaming for a "hub" is lobbyists' nonsense. London's trading future lies in being a terminus, not a transit lounge. Anyway, a mere 15% of London air travel is business rather than pleasure, the latter overwhelmingly that of outbound Britons. Why boosting Britain's £15bn tourism deficit holds the key to economic recovery is a mystery.

There is nothing to stop Heathrow serving more business destinations if BAA and BA wanted. Instead they are addicted to outbound leisure travel, as is glaringly obvious from any Heathrow departure board. As for inbound tourists, far more harm is done by Cameron's clampdown on their visas than might be done by directing them to Stansted or Gatwick.

BA prefers to work out of Heathrow, while Spanish-owned BAA has sold both Gatwick and Stansted and has no interest in their growth, let alone in a new Thames airport. These are two companies with a commercial interest in Heathrow, pure and simple. They are continuing to press for a third runway for one reason alone. Cameron and George Osborne have shown they will bend under pressure. While this is sometimes the welcome reversal of a bad decision, each U-turn is a gift to the lobbyists.

Cameron famously said in opposition that "secret corporate lobbying, like the expenses scandal, goes to the heart of why people are so fed up with politics". Money, he said, was "buying power, power fishing for money, and a cosy club at the top making decisions in their own interest". He spoke the truth. Can he now not recognise the evil when he sees it?

This week's Guardian poll shows the pressure on the government to show lateral thinking on the economy. The demand takes a drearily familiar form, that Cameron sack Osborne rather than change his recovery policy. With the American and German economies now showing signs of growth, the danger of Britain "sliding back to insignificance" is real. But the pressure from Yeo and others is to halt this slide, not through a desperately needed stimulus to liquidity and demand, but through "infrastructure projects".

Not a day passes without a call for something big, brash and financially sexy: a road, an airport, a railway, a power station. Economists get on TV if they call for more infrastructure, even when such projects take years to get off the ground and benefit only professionals and consultants in the short term.

The British class system is nowhere more apparent than in this pressure. An economic stimulus that puts money directly into the pockets of consumers through higher benefits and/or lower taxes is bad, indeed possibly immoral as corrupting expectations. It is thought vulgar to print money for people to spend through their wallets and credit cards. On the other hand, a stimulus that aids "investment" is automatically good. As we saw last month, Olympic stadiums are good, school playing fields are bad. Third runways are good, local transport bad. Developers want hypermarkets and eco-cities in the countryside, not healthier high streets and urban renewal.

The Treasury and the Bank of England seek to "pump money into investment", even when they know it merely disappears into a bank vault. Money can be printed but not for ordinary people to spend. It must be conduited through government agencies, banks, boards and consultants. It thus becomes "clean" and can even be declared "below-the-line and off-budget". Nobody trusts ordinary people to rescue the British economy. The only good spending is government spending on infrastructure. It makes no sense.

The best thing Cameron could now do is meet Yeo's challenge. He should show himself a man, not a mouse. He should get Yeo expelled from the Commons energy committee for blatant conflict of interest. He should declare closure on the third runway nonsense. He should tell the toffs and tycoons of the infrastructure lobby that consumption, not investment, is today's absolute priority. A recession is no excuse for collapsing environmental standards or pushing through dumb projects.

Cameron might take note that the chief lobbyist for BAA is a firm called Blue Rubicon. He now faces his blue Rubicon. Dare he cross it, and send the mice scampering?