The onset of a downturn is as much a matter of mood as of money

IN RECENT WEEKS the human and silicon brains at Google have registered an alarming rise in searches related to “recession”. It is easily explained. As markets gyrate, talk in the press (including this very column) turns to the risk of a slump. Even so, the stories must leave some Googlers baffled. In July, after all, the American economy added 164,000 jobs and retail sales kept climbing. President Donald Trump, too, is bemused. He has taken to warning darkly that conspirators are attacking his presidency by frightening the economy into an unnecessary downturn. The claim of conspiracy is absurd, but the threat of recession is not. Recessions can indeed appear as if out of the blue.