Excited crowds of youth, encouraged by adults who should know better, take the view that opinions with which they disagree should not be debated but subject to control by the mob. In the ancient world we know of only a handful of examples. Socrates’s trial is the most famous: at a politically fraught time in 399 bc, he was executed on a charge of impiety, i.e. atheism (it was widely believed that if gods were unacknowledged, Athens would be in trouble). But thinkers long debated the subject quite freely: here are two from an extensive list.

Assume the existence of traditional beliefs about the gods was of the same importance today and imagine what the mob would have to say about Xenophanes (died c. 475 bc).

Here he says of the gods: ‘Mortals consider that the gods are born and that they have clothes and speech and bodies like their own. The Ethiopians that their gods are snub-nosed and black, the Thracians that theirs have light blue eyes and red hair. But if cattle and horses and lions had hands, or were able to draw with their hands and do the works that men can do, horses would draw the forms of the gods like horses, and cattle like cattle, and they would make their bodies such as they each had themselves.’ One can imagine he would not last long.

Take Critias (died c. 406 bc), likely author of a play about Sisyphus, an evil figure of myth. Here Sisyphus argued that a lawyer, wishing to stop crime, had invented the idea of immortal gods, living in the heavens, a place of wonder and terror, who heard man’s every word, witnessed his every act and even saw into his thoughts. The idea caught on, and that was how men came to believe in them. No one brought a charge against him. Time, therefore, for brilliant young and old thinkers to steer well clear of the Greeks (and Romans). They set a terrible example. It is obvious that, in this enlightened age, your right to cancel debates overrides everyone else’s right to stage them.