Arnold Kling opens his most recent essay, Appreciating Our Moral and Mental Development, by citing Steven Pinker on the decline of violence:
In 16th century Paris, a popular form of entertainment was cat-burning, in which a cat was hoisted on a stage and was slowly lowered into a fire. According to the historian Norman Davies, “the spectators, including kings and queens, shrieked with laughter as the animals, howling with pain, were singed, roasted, and finally carbonized.”As horrific as present-day events are, such sadism would be unthinkable today in most of the world. This is just one example of the most important and under appreciated trend in the history of our species: the decline of violence.