Don't bother with The Better Angels of Our Nature. I think you have to be very careful before buying anyone's ponderous 800 page tome. (I wasn't fooled into buying Piketty, but look how many copies of his are going to have to be pulped.) Unless the author is an utter genius crystallizing some subject for the rest of us, the result is going to be a muddled mess.
Since Pinker uses "'six trends' interacting with 'five inner demons,' 'four better angels,' and 'five historical forces,'" to attempt to explain his hypothesized decline of violence, I think we can tell it fits squarely in the muddled mess category. (Twenty degrees of freedom in the model!)
And with one paragraph, Steve Sailer crushes Pinker for writing a politically progressive, anti-Christian book:
[T]he single most obvious bit of evidence in support of Pinker’s theory that there has been a long trend away from violence is the change in morality from the Old Testament to the New. Pinker recounts at length some hair-raising anecdotes passed on without criticism—indeed, often with approbation—in the Hebrew Bible, such as the tale of what the 12 sons of Jacob did to Hamor the Hivite. Yet when the author’s attention turns to the New Testament, with its radically different moral climate, he’s barely able to begrudge an acknowledgment of this epochal change. He quickly quotes Jesus saying, “I came not to send peace, but a sword.”I am actually convinced by Pinker's argument that homicide has declined precipitously, and that people value life much more than 500 or 1000 years ago. This makes sense because untimely death from accident or disease is less common and life is easier.
I am not convinced that there is anything meaningful about the current 70 year break since the world wars. Isn't it just a nuclear stalemate that will one day be broken? Remember E.O. Wilson,
"The foreign policy of ants can be summed up as follows: restless aggression, territorial conquest, and genocidal annihilation of neighboring colonies, wherever possible. If ants had nuclear weapons, they would probably end the world in a week."Territorial conquest and genocidal annihilation was the foreign policy of early humans, too. Ask the Neanderthals. Well, since they aren't around to ask, then ask Gregory Cochran and Henry Harpending.