There is nothing particularly new about conspiracy theories. Anti-Semitism, the most enduring and pernicious of them all, can be traced back to the early Middle Ages at least. But the modern era appears to be particularly prone to beliefs which seek to assign blame for the ills of the world to a secretive, malevolent cabal. An NPR/Ipsos poll in 2020, for example, found 17 per cent of Americans believed the QAnon theory that Satan-worshipping, child-abusing elites were trying to control US politics and media. A further 37 per cent were not sure whether the theory was true or not. New...