Joe Biden is no longer mentally well enough to be president

THE spectacle of Joe Biden's psychological and cognitive decline is both sad and deeply alarming. At a press conference in Hanoi on Sunday, the 80-year-old US president was cut off mid-flow by his aides after yet another rambling and often incomprehensible performance in which he described climate change deniers, bafflingly, as "lying, dog-faced pony soldiers" and appeared to confuse the movie Good Morning, Vietnam with a song.

- Matthew d'Ancona

Since 1973, American psychiatrists have observed the so-called "Goldwater Rule" that clinicians do not offer public opinions on, or diagnose those whom they have not personally evaluated; this followed an ugly controversy in the 1964 presidential election in which more than 1,000 of them had declared Barry Goldwater, the Republican nominee, unfit for office. And - more generally - this has discouraged journalists and other observers from commenting recklessly upon the psychological state of politicians.

In Biden's case, however, the evidence is simply undeniable. In March, on the day of the Nashville school shooting, he said: "I came down because I heard there was chocolate chip ice cream." In June, the president ended a speech in Connecticut with the words.

"God save the Queen, man". In the same month, he declared that Vladimir Putin "is clearly losing the war in Iraq" and announced "plans to build a railroad from the Pacific all the way across the Indian Ocean".