If you really want proof of the folly of trusting markets as a guide to what is happening in the real economy, let alone the real world, you only have to look at the antics in Tokyo over recent days. The government announced that growth in the final quarter of 2015 fell by an annualized rate of 1.4 percent, and the yen had appreciated to 113 against the dollar in spite of Bank of Japan Gov. Haruhiko Kuroda's best efforts. And yet, confronted with this gloom, the Tokyo stock market rose by a massive 7.2 percent in a single day.

Similar unfathomable gyrations have been happening in other major markets. In particular, the falling price of oil — which should be like sakura to spring, a harbinger of better economic times — sent Mr. Market into a scared tailspin. Such is the nervous mood that rumors of unlikely collusion between a motley group including Iran, Qatar, Russia, Saudi Arabia and Venezuela about a possible deal on supplies sent the oil price above $35 a barrel, and stock markets galloped giddily higher.

Whatever the stock markets think, the world economy is in a mess, as the OECD, the club of rich industrialized nations, admitted. It cut growth forecasts made only three months earlier, and sharply told member governments that reliance on low interest rates and money creation through quantitative easing (QE) was no longer enough for lasting recovery.