We are being overwhelmed by dangerous nonsense. From 9/11 conspiracy theories to Holocaust denial, from creationism to unorthodox medicine, there is now an epidemic of demonstrably untrue descriptions of the world.

For Damian Thompson, these unproven theories and spurious claims are forms of 'counterknowledge'; spread not least by the internet, they are creating a global generation of misguided adherents who repeat these untruths and lend them credence.