Anyone watching the first presidential debate would be forgiven for thinking the US was on the brink of collapse. The Republican candidate, Donald Trump, insisted the US was a third-world country suffering an almost biblical flight of jobs to China and beyond. Violence was out of control and parts of the country were now in open warfare.

Hillary Clinton’s language may have been rather less melodramatic. But she shared Mr Trump’s premise about the threat posed to the US by an open global economy. She declined the chance to re-embrace the Trans-Pacific Partnership that she once labelled a gold standard of trade deals. She also failed to spell out what kind of America the world should expect if she were to succeed Barack Obama. Their message to Americans was: “Be afraid. Be very afraid.” The rest of the world should take note.

The big puzzle is the gap between the relatively healthy reality of the American economy, particularly compared with Europe and Japan, and the dystopia gripping its politics. Contrary to Mr Trump’s depiction of a jobless America, the US unemployment rate is just 4.9 per cent, which is less than half that of parts of Europe.