‘We are the United States of Amnesia,’ said Gore Vidal in 2004. These days, it’s more the United States of Dementia. In 2020, the country seems determined to choose between two elderly men who, it is fair to say, are some distance from sanity. Joe Biden, the 77-year-old who even aides admit has lost his ‘cognitive fastball’, has somehow emerged as the presumptive Democratic nominee.