When I was a little boy, my mother liked to quote the following quatrain (sometimes attributed to the New York wit Dorothy Parker): “See the happy moron, / He doesn’t give a damn, / I wish I were a moron, / My God! Perhaps I am!”

I often think of the happy moron when I settle down to the read the International Monetary Fund’s (IMF) biannual publication World Economic Outlook. Almost without fail, this publication acknowledges that its previous projections were too optimistic and need to be revised downwards.

In fairness to the IMF’s economists, they do give a damn. Indeed, two years ago the fund published an introspective paper on its forecasts, concluding that they “tended to be consistently overoptimistic in times of country-specific,