The shift will occur with the advent of cheap artificial meat. Technological change has often helped to catalyse ethical change. The $300m deal China signed last month to buy lab-grown meat marks the beginning of the end of livestock farming. But it won’t happen quickly: the great suffering is likely to continue for many years.

The suffering inherent in mass meat production can’t be justified. And as the artificial meat industry grows, the last argument for farming animals has now collapsed.