Governments can choose to focus on cutting spending, or they can try to increase revenue. These further economic shocks show that, in focusing exclusively on cutting spending, they have made the wrong choice.
The problem is that the level of debt is a function of the level of economic activity; the higher the level of economic activity, the more buoyant the government's tax revenue.
A government that has trouble balancing its books in a recession, and seeks to deal with that issue exclusively by cutting its spending, necessarily reduces the level of economic activity and - by depressing its tax revenue - makes the debt problem more difficult to resolve.
Sadly, we have seen extreme examples of this error in the economies that have spawned the current crisis. In the US, the Republican majority in the House of Representatives has been wagged by the Tea Party tail, with the result that the usually technical issue of raising the Government's debt ceiling became an issue of moral probity.
The Republicans not only resisted any increase in the Government's ability to borrow but refused to countenance any reversal of the tax concessions that George W. Bush made to the super-rich.
A refusal to allow any tax increase, and an insistence on huge spending cuts in the short term - while the economy is still in recession - have rightly been seen by the credit rating agencies as a cause for concern.
In Europe, the problems are more structural. The eurozone lured into its membership smaller and weaker economies - and some not so small - that could not hope to live with monetary conditions established to suit the interests of the dominant German economy. Those countries were lulled into a false sense of security when money and credit were plentiful; but - come the recession - they are now denied the usual remedy of devaluing their currencies. The only course open to them is savage cuts and austerity.
The problem with austerity as a supposed remedy is that closing economies down in an effort to cut spending means that they cannot hope to repay the enormous further borrowing they need just to keep their heads above water. Little wonder that European banks look nervously at the probably worthless securities they hold from deficit countries, that bank failures are now seen as a grim possibility, and that contagion threatens to spread not only throughout the eurozone but across the global economy.
The problem is less stark in Britain, which sensibly stayed out of the eurozone. But there, the damage is self-inflicted.
The coalition Government, elected last year, has insisted that giving priority to savage cuts in spending will give confidence to the money markets, a view thoroughly discredited by the US and eurozone experience, and - as the "confidence fairy" fails to materialise - by the increasingly obvious failure of the British economy to recover from recession.
The only fairy that has made its presence felt has been a very wicked one indeed. The recession - and, in particular, rising levels of poverty, high levels of youth unemployment, severe reductions in post-compulsory educational opportunities, and sharp increases in public sector rents - has certainly played its part in creating the conditions for last week's shameful riots.
Each of the many thousands of individual acts of criminality should of course be condemned and punished. But it is pointless and wrong to ignore the fact that riots on this scale are a social phenomenon.
Many of us will have been bewildered by the absence - in the television pictures broadcast around the world - of any decent impulse, any sense of social responsibility.
But the young people who behaved like a feral rat pack feel that they owe very little to a society that has banished them to its extreme margins and that treats them as worthless.
This is not a question of making excuses, but an attempt to find an explanation for what is otherwise inexplicable to most people.
And before we bless our own good fortune in New Zealand, let us recognise that many of these conditions apply here as well.
We have a Government that talks of nothing but deficit reduction while the developed world's worst youth unemployment is allowed to fester. Like misguided governments overseas, given the choice between austerity and jobs, we have made the wrong choice.
