Pinker identifies five "historical forces" that have favored "our peaceable motives" and "have driven the multiple declines in violence." They are:
The Leviathan – the rise of the modern nation-state and judiciary "with a monopoly on the legitimate use of force," which "can defuse the [individual] temptation of exploitative attack, inhibit the impulse for revenge, and circumvent ... self-serving biases."
Commerce – the rise of "technological progress [allowing] the exchange of goods and services over longer distances and larger groups of trading partners," so that "other people become more valuable alive than dead" and "are less likely to become targets of demonization and dehumanization."
Feminization – increasing respect for "the interests and values of women."
Cosmopolitanism – the rise of forces such as literacy, mobility, and mass media, which "can prompt people to take the perspectives of people unlike themselves and to expand their circle of sympathy to embrace them."
The Escalator of Reason – an "intensifying application of knowledge and rationality to human affairs," which "can force people to recognize the futility of cycles of violence, to ramp down the privileging of their own interests over others', and to reframe violence as a problem to be solved rather than a contest to be won."
Having effective, more or less trustworthy police and courts goes a long way toward both making violent behavior risky, and reducing the need for vigilante justice/vengeance violence. And civil courts help resolve disputes without resorting to violence.
Likewise, trade and economic stability have become so effective that it makes little sense for nations to engage in war with their neighbors anymore. War is bad for business!
Looks like an interesting book.
I know that percentage wise, violence has been decreasing. But is it simply that modern governments are bigger, more powerful, and can better contain and direct violence? Or are modern people actually less violent as far as their culture and psychology? I wonder because even in modern times we've seen incredibly developed and cultured societies turn violent and gruesome very quickly.