I've always enjoyed Steven Pinker's books and essays. He's a truly thoughtful scientist. This question and answer piece on parlio is a great example of his clear and logical thinking. Even when the questions veer toward unimaginative or ignorant, his responses are still thought provoking and to the point. There's too many good ideas to quote them all so I'll leave the core principle here as bait.
That the human condition is improving. It's not just violence, but every other measure of human well-being that is on the rise: longevity, literacy, health, affluence, education.