Steven Pinker's big insight is that he see a long term decline in the amount of violence, of all kinds, that humanity experiences. His latest book is "The Better Angels of Our Nature." He is one of the foremost authorities making an empirical case that the progress of civilization is a meaningful concept. But, it is also possible that some of what he is seeing is selective marshalling of evidence. Gene Expression has devoted a couple of posts in the last few days to his thesis.