Niall Ferguson is not given to understatement. So I was not surprised by the claim last week that the US will face a Greek crisis. I promptly dismissed this as hysteria. Like many other high-income countries, the US is indeed walking a fiscal tightrope. But the dangers are excessive looseness in the long run and excessive tightness in the short run. It is a dilemma of which Prof Ferguson seems unaware.

Prof Ferguson stated that, according to the White House projections, gross federal debt will exceed 100 per cent of gross domestic product by 2012; that the US is forecast never to run a balanced budget again; that monetary policy, not deficits, saved the economy; that higher interest rates are on the way; and, not least, that high fiscal debt is damaging.

Brad DeLong of the University of California, Berkeley, responded that parts of this argument are wrong or misleading: White House projections are for federal debt held by the public to be 71 per cent of GDP in 2012 and not to exceed 77 per cent by 2020; monetary policy would not have delivered even the limited recovery we have had on its own; and higher interest rates may indeed be on the way, but there is nothing in current yield curves to suggest it. Moreover, there is no reason to balance budgets in a country whose nominal GDP grows at up to 5 per cent a year in normal times.