I think that communism was a major force for violence for more than 100 years, because it was built into its ideology - that progress comes through class struggle, often violent.
Steven PinkerThe foundation of individual rights is the assumption that people have wants and needs and are authorities on what those wants and needs are. If people's stated desires were just some kind of erasable inscription or reprogrammable brainwashing, any atrocity could be justified.
Steven PinkerNo one knows what the nongenetic causes of individuality are. Perhaps people are shaped by modifications of genes that take place after conception, or by haphazard fluctuations in the chemical soup in the womb or the wiring up of the brain or the expression of the genes themselves.
Steven PinkerThe European wars of religion were more deadly than the First World War, proportionally speaking, and in the range of the Second World War in Europe. The Inquisition, the persecution of heretics and infidels and witches, they racked up pretty high death tolls.
Steven Pinker