As the pandemic lockdown continues, governments and central banks in the world’s largest economies are responding with stimulus programs aimed at limiting the damage while holding societies together. But as the paralysis persists and deepens, the odds of a rapid “V-shaped” economic recovery are fast diminishing.

Our 2009 book, “This Time Is Different,” documents financial crises over eight centuries. A central theme, controversial at the time of the global financial crisis, is that recessions that are accompanied by severe...