We are living, it is often said, in a golden age of stupidity, in which boneheaded, mendacious politicians get elected by voters who've become too mindless to realize their interests are ill served by narcissists, while vapid social media influencers corrupt their no less witless followers with groundless conspiracy theories and eye-wateringly foolish takedowns of scientific expertise. Our time, one might be forgiven for thinking, is one in which the fool's gold of stupidity has become a desirable commodity, a must-have, with bumbling celebrities venerated more than those who have more than two brain cells to rub together. In this book, Stuart Jeffries analyses how we got into this parlous state and wonders if the stupid, like the poor, are always with us, or if, rather, stupidity is like Japanese knotweed, difficult to root out but to be exterminated with extreme prejudice. He considers what some of the greatest of minds - Socrates, Buddha, Voltaire, Arendt, and others - have to tell us about the slippery nature of stupidity. During a narrative that takes us from ancient Greece to artificial intelligence, and accompanied by such heroes of stupidity as Flaubert's double act Bouvard and Pécuchet, Jeffries casts a sceptical eye on attempts to root out stupidity by such means as IQ tests, eugenics, gene editing, and racist education policies, finding each attempt to be more stupid than the stupidity they were ostensibly devised to eradicate. If today we are living in a fool's paradise, has our species become too dim to learn anything from its rich history of folly?