New Delhi, April 9 -- Donald Trump has put paid to the world's proverbial 'Raaton ki neend and din ka chain' (night's sleep and day's peace) as everyone now tracks index and future quotes from around the world around the clock. His tariffs have created a sensation, but what I wonder about is the problem he is trying to solve.

After all, the US was pretty close to full employment and its labour market has been fairly tight for years. Inflation had begun to float down. So it is inexplicable why he would break something that wasn't broken.

As Fareed Zakaria set out in a recent video, in 1990 the US economy was the same size as the EU's. It is now almost 85% larger. In 1990, the US per capita income was way below Japan's. Today, not only is...