Who are they? Where are they now? They said it could not happen again. They said they were masters of the universe. They had conquered history itself and had that wily monster quivering at their feet. There would be no more crashes, no more recessions, no more booms and busts, just moonbeams and rainbows and jam for tea.

If the mistakes that have collapsed the world's financial markets had been made by statesmen and had led to war, there would be corpses swinging from lampposts. If they had been made by generals, they would be falling on their swords. If they had been made by judges or surgeons or scholars, some framework of professional retribution would be rolling into action. But those responsible for our finances can apparently vanish into the forest like Cheshire cats, leaving only gold-plated grins. Not for them a Hague tribunal or a Hutton inquiry. They are not just good at shedding risk - they shed blame.

We are seeing what historians of ideas call a paradigm shift. In the last century, the necessities of war and the rise of socialism thrust government intervention to the fore. When that failed in the 60s and 70s, the "Reagan-Thatcher revolution" turned the emphasis back to private enterprise and deregulation. That era has ended with astonishing abruptness. Governments in Britain and the US have been nationalising and spending public money with a will that would have made Attlee or Roosevelt blush.

Those of us who learned economics in the old days were taught that banks had to be regulated oligopolies because their role in a capitalist economy was crucial. It relied on the sustenance of public trust which only government, backed by the citizen as taxpayer, could dispense. In Britain, retail banks, merchant banks and building societies were legally distinct, separated by barriers to prevent cross-pollution of the sort that caused the 1929 crash.

JK Galbraith's book on that crash is the Dr Strangelove of financial holocaust. If it offers one lesson, it is that crashes are not acts of God; they are caused by the interaction of corporate behaviour and state regulation. Nor does the market supply its own discipline. Understanding that, wrote Galbraith, "remains our best safeguard against recurrence".

Such lessons learned in youth tend to stick. Hence I remember feeling queasy when Thatcher's "big bang" of 1986 demolished the firewalls and permitted the trading of risk and reward across the entire financial sector. It was a reform repeated in the US with the repeal of the post-depression Glass-Steagall law. The same nervousness greeted each subsequent shock to the system - the 1991 housing crash, Lloyd's of London, Barings, Enron, Northern Rock. Each time we were assured that new lessons had been learned. Light-touch regulation was working fine, even if sometimes boys will be boys.

The naivety of all this is now exposed. Politicians encouraged the public to treat home ownership as a "right"; property became the citizen's gilt-edged stock. Bankers encouraged staff to speculate with depositors' money by awarding them huge bonuses to maintain turnover. Those charged with the guardianship of other people's savings behaved, in effect, like thieves. Sheer greed drove young men and women mad. Nobody in authority batted an eyelid.

At the same time Gordon Brown "set free" the Bank of England to fix interest rates. I recall one commentator telling me that I should be "overjoyed your children and grandchildren will now never have to experience inflation". No, they are just unemployed. It was a charade. On the back of low inflation, the Bank fuelled a credit boom that was clearly vulnerable if prices rose and/or credit collapsed. Both have occurred.

There is no such thing as a "non-political" official rate of interest. The Bank is now under pressure both to cut rates to beat recession, and yet raise them to beat inflation. It cannot do both. Since it would be 1929-style lunacy to increase rates just now, Brown must in effect tell the Bank to reduce them by shifting his inflation target. It is a blatant and properly political decision.

There is no perfect market. Markets need regulation, just as communities need law. Yet as Galbraith again wrote, regulators may start life "vigorous, aggressive, evangelical, even intolerant", but mellow with age and become "an arm of the industry they are regulating - or senile".

To ignore the danger in 125% mortgages or the City bonus culture showed both industry capture and senility. The first was loan-sharkery, and the second was obscene. So distorting to sound finance are year-end bonuses that they should simply be banned. Those with the responsibility of gambling with other people's savings should do so on salary.

While naive Thatcherism may have taken a pasting, there is no reason why capitalism should protest the presence of big government in what is its proper realm. We do not curb state power when the security of the state is at risk. Nor should we do so when the security of the economy is equally jeopardised.

The strangest phenomenon these past few days has been the eagerness to enforce "moral hazard", a concept regarded by the governor of the Bank of England as a deterrent to risk-taking. This is absurd. The collapse of Enron was no deterrent to Lehman derivative traders. The psychology of money does not work that way. The victims of the credit crunch are not just a few wild traders. They are all participants in the UK economy. I cannot see the sense in letting Northern Rock or Lehman or any other deposit-holding institution go bust just so regulators who have failed in their jobs can seem macho after the event.

This is not a question of blowing taxpayers' money on fat cat financiers. I would happily arrest and try all those whose stupidity and greed are about to cause untold hardship to millions - if I could find a law they had broken. Dr Johnson was quite wrong to say a man is "never more innocently employed than in getting money". But when a building collapses, you do not kill the architect. You try to get him to build it again.

Underpinning financial credit is an absolute function of government and one that has not changed since the birth of capital. It clearly needs constant redefinition. When this saga is through there should be a tribunal of inquiry. Then we can be told what needs mending, and whom to take out and shoot.

simon.jenkins@theguardian.com