So what does Pinker’s analysis tell us about the future? He refrains from speculation, noting the role of contingency and statistical distributions with “fat tails”—i.e., unexpected events with large consequences. But this sensible if cautious stance does not sit entirely well with his central argument. If knowledge, reason and the free flow of ideas have brought violence down in the past, they should continue to do so in the future. It would seem highly likely, perhaps even inevitable, that free societies would develop even further where they are established and spread—if at uncertain pace—where dogma now reigns, with the result that the world would be even better in the coming generations. Once stated, this seems too triumphalist if not reminiscent of George W. Bush, but it is to be welcomed both as a vision and a benchmark against which Pinker’s argument can be judged by our successors.

In the end, even if Pinker’s explanations do not entirely convince and his faith in reason is exaggerated, he has succeeded in documenting the enormous decline in all sorts of violence and cruelty. This achievement of humankind deserves to be better known, and readers of this important book will remember it and ponder its causes. It is a story worthy of seven hundred pages.

Robert Jervis is the Adlai E. Stevenson Professor of International Politics at Columbia University.

Pullquote: The fact—if it is accepted as a fact—that violence has declined so much in so many forms changes the way we understand our era and the sweep of human history.Image: Essay Types: Book Review