Inside Investment: Of hedgehogs, foxes and mere human beings

At a time when the advanced economies are seemingly teetering between inflation and deflation, it is worth recalling Sir Isaiah Berlin’s essay, "The hedgehog and the fox". It begins with a quote from the Greek poet Archilochus: "The fox knows many things; the hedgehog knows one big thing." Berlin believed that we are all either foxes or hedgehogs. We are impressed and distracted by the subtlety and cleverness in many foxy things, but today we need the single-minded certainty of the hedgehog and his deep knowledge of the one important thing.

I have some experience with porcupines, hedgehogs’ even pricklier American cousins. In the small farming town of Middlefield in the Berkshire Hills of Massachusetts where I grew up, nature was encroaching. The population had peaked in the early 1800s at more than 2,000 but was down to 300 by the time I was born. By then, the...