steven pinker is the author of the book "better angels of our nature." dr. pinker, you say people are less likely to see a violent death than any other point in history. you spend six chapters. give me the cliffs notes version now if you would. >> violence has declined on many scales of time and magnitude. homicide is down compared to centuries ago. wars are less common and deadly. domestic violence is down. racial minority violence is down. people spank their kids less than they used to. any way you want to measure violence, the trend is downward. >> even when you control for war, that trend has been downward? >> that is right. most dramatically since the end of world war ii.