The curious and furious recovery has brought some old ideas back to the fore

Science advances one funeral at a time, to paraphrase Max Planck. The Nobel prize-winning physicist was arguing that new ideas in his field would only catch on once the advocates of older ones died off. With a little adaptation he could have been describing the dismal science, too: economics advances one crisis at a time. The Depression provided fertile soil in which John Maynard Keynes’s theories could grow; the Great Inflation of the 1970s spread Milton Friedman’s monetarist ideas; the global financial crisis of 2007-09 spurred interest in credit and banking.

Sure enough, the recovery from the covid-19 pandemic has given economists another chance to learn from their mistakes. Papers presented at the recent conference of the American Economic Association (AEA) offer clues as to the theories that might eventually become the received wisdom of the next generation.

One such paper takes a harder look at the Phillips curve, which describes a theoretical trade-off between unemployment and inflation. When unemployment is low, the logic goes, inflation should be higher, as competition for workers exerts upward pressure on wages. In turn, consumer prices rise. Yet during the 2010s the curve appeared to have vanished. Unemployment kept falling but inflation stayed quiescent. Then, after the pandemic, the relationship suddenly seemed to re-exert itself: inflation rose as swiftly as unemployment fell.