The Better Angels of Our Nature, Why Violence Has Declined

The decline in personal violence from medieval times to the present is called civilizing process after sociologist Norbert O'leus. There was the humanitarian revolution of the enlightenment, the abolition of cruel and unusual punishment within a 50-year period. None of them are linear or even monotonic. They're always lurches and blips. Sometimes there are horrific reversals like the two World Wars.