Blame the Germans. The global commentariat, from international organisations to the media and some restless politicians, has found a rare consensus: Berlin's refusal to bust its budget - sorry, the German government's reluctance to enact a big fiscal stimulus that could spill over to its neighbours - is one reason why the fight against global recession is not yielding enough results yet.

The pro-stimulus pundits have a point. Because the Germans painfully tightened their belts to repair their budget while others feasted on a credit-fuelled public or private sector spending spree, Germany's fiscal starting position is less precarious today. But beyond recanting current fiscal and trade statistics, most calls for a big German bang to help save the world defy economic logic, ignore history and disregard the political dynamics.

Start with history. Germany had twice granted its friends the wish to stimulate domestic demand artificially against its own better judgment. The "locomotive" experiment of 1979-80 and the smaller easing of 1988-89 both ended in tears, destabilising the economy and fuelling inflation.

Now look at the economic logic. Germany has fallen into a deep recession because the super-cyclical demand for its exports of reliable machines and flashy cars has collapsed. Would not the obvious solution be to boost consumption to offset the external hit? Well, think again. German consumers do not lack the money to spend. Helped by still rising employment, disposable incomes were up 3.1 per cent in the third quarter. The point is that Germans are not spending the money they have, raising their savings rate instead, from 10.7 per cent of disposable income last autumn to 11.4 per cent now. Imagine a British-style programme to cut taxes now only to raise them with a vengeance later. There would be no better way to confirm German angst that government will hit them hard with higher taxes and lower pensions in the future, and thus to get them to save even more while they still can.

Germans also remember that previous programmes to combat recession by letting the government spend more turned into blatant wastes of money, with much of the spending coming too late to smooth the cycle anyway.

Of course, the current recession is unusually deep. With the banking system too paralysed to transmit the European Central Bank's monetary stimulus into the real economy fully and fast, the case for fiscal action is strong. But only a stimulus designed to work could be worth the costs.

Any German fiscal stimulus must strengthen the labour market to ease the mounting fears about job losses. Only this could convince consumers not to shut their purses even more tightly. To enable businesses to keep their workers, Berlin has to cut corporate and payroll taxes. Slashing corporate tax liability due for 2008 by half, up to a limit and excluding the energy and utility sectors, and reducing tax rates for 2009 would give businesses extra breathing space when they need it most and make them less dependent on hard-to-get bank credit. By lowering wage costs, a permanent reduction in payroll taxes would also promote employment and long-term growth potential.

Now turn to the politics. Chancellor Angela Merkel's Christian Democrats share power with the Social Democrats. They can hardly agree on anything. Merkel's one big achievement is to have balanced the national budget with a tax rise that both parties had signed up to before they formed the government. Burning this trophy now in one big bonfire would not come easily.

Ten months ahead of an election, the odds that the two camps in government could design a worthwhile stimulus focusing on lower corporate and payroll taxes are not encouraging. The German left might howl that lower business taxes reward the rich. Instead, once the dyke of fiscal discipline is breached, right and left in Berlin may simply add up their pet projects regardless of costs and logic. Unfortunately, the motley collection of disparate initiatives that parliament passed last week as a first small stimulus proves exactly this point.

If Ms Merkel believes that, as the recession deepens, she could get a real stimulus programme by her business-wary coalition partner, great. But if she judges the risk that - in the political process - a think-big initiative could degenerate into a scary porkfest with a UK-style tax gamble tacked on to it, Germany - and ultimately its neighbours - would be better off without it.

The writer is chief economist, Europe, at Bank of America