There are some questions in finance to which the obvious answer is: yes, of course. Here are a couple. Does it matter if the US Congress cannot agree to an increase in the country's borrowing limit by August 2 — the date, so we are told, that the US hits its present debt ceiling?

Would it be bad for the world economy were the US to default on its debt?

Obvious answers, but not necessarily the right ones.

As far as the first is concerned there is a little wriggle room, so some delay in increasing the debt limit would not have an immediate effect. Eventually the ceiling would be lifted and meanwhile there might be some delay in Federal payments.

The debt ceiling has been increased 11 times since 1996 and there has nearly always been a tussle between Congress and the administration before this has been agreed.

A government shut-down happened twice during the Clinton administration, in 1994/5 and again in 1995/6. On both occasions the Federal government had to juggle around with payments, holding some back, while the legislators deliberated.

That may well happen again, with President Barack Obama suggesting that some social security payments might not be paid. However, the general view seems to be that some payments might be delayed, but that a deal will be reached. It just may take a little while.

As far as a default is concerned, that would occur were the US to miss interest payments on its debts. The official view is that this would be a disaster. Speaking on Wednesday this week, the Federal Reserve Chairman, Ben Bernanke, was clear enough.

“Failure to [make these payments] would certainly throw the financial system into enormous disarray and have major impacts on the global economy,'' he said.

Clear, but maybe wrong.

There would, of course, have to be a downgrading of US debt: the country would inevitably lose its AAA credit rating. The agencies are warning of this already.

In the short term, at least, US financing costs would increase as I expect that some foreign investors would dump stock. But if you stand back, the long-term effect of a reasonably lengthy delay in increasing the debt ceiling and a default on interest payments might be positive. Here is why.

There are two points. First, US levels of absolute debt are not that high by world standards.

Second, the US budgetary process is ill-disciplined and needs to be reformed.

On the first, if you look at net levels of Federal debt relative to GDP, the US is middle of the pack: not great but not dreadful. It is in better shape than the UK is.

But those figures are just snapshots of debt at the end of last year. They don't take into account the growth potential of different economies, nor the population trends and other indicators.

On all these measures, the US is in better shape than the rest of the developed world. It has an increasing population and the room for it to go on increasing for many years to come.

Put it this way. Debt is being accumulated in the US by 300m people, but in another 40 years there will be 450m to pay it off. In Italy, debt is being accumulated by 60m but in another 40 years there may be only 50m people to pay it.

However, and this is the second point, the US budgetary arrangements are so dreadful that they are undermining this fundamentally sound position.

The baseline projections from the Congressional Budget Office are for the running deficit, currently nearly 10% of GDP, to fall below 3%, a level which would be roughly the same as the potential increase in output of the economy.

That would stabilise debt as a percentage of GDP, not reduce it. This would not leave any room if there was another recession.

The situation may be much worse than that. Alternative, and arguably more realistic, projections by the CBO suggest that the deficit may get stuck at around 6% of GDP. That would be unsustainable, even for a country that runs the only world reserve currency and which its chief trading partner, China, is prepared to finance.

Something needs to clonk it on the head before the US really does put itself in a position where it has inevitably to default in some way, perhaps by a sharp devaluation of the dollar. That something may turn out to be the debt ceiling.