Did the emergence of the state reduce the rate of human death from warfare? Steven Pinker’s outstanding book, The Better Angels of Our Nature: Why Violence Has Declined, surveys many reasons why you are less likely to die from violence today than your ancestors were. Part of his explanation is that warfare was constant in stateless, anarchic societies, but the emergence of the state, beginning about six thousand years ago, helped reduce this problem. He has nice things to say about Thomas Hobbes’ thesis in Leviathan, that a powerful government is necessary to rescue people from their natural state of constant warfare.
In my most recent Learn Liberty blog post, I question this finding of Pinker’s. I argue that the evidence he presents for the claim does not suffice to prove it, because there are other factors that could explain declining rates of war death. Moreover, even if the state reduced war death somewhat, we can’t necessarily infer from that fact alone that the state increased human welfare. From the post:
[T]here is an important conceptual problem for the claim that the rise of the state improved human welfare by reducing violent deaths.
After all, early states arose almost exclusively out of conquest, as Pinker concedes. They started as roving bands of armed robbers, who eventually found that converting robbery into regularized taxation would destroy less wealth and generate more revenue over the long run. Autonomous peoples do not go into “subject” status willingly.
PILEUS 
Somewhat along the lines of your critique, John Keegan wrote a book called “The History of Warfare”. He documents various cultures, throughout history and the reasons they may have waged war. He states that the reasons that people in stateless societies battled their neighbor are often the result of cultural mores which people who live in modern nation states can’t imagine must less abide by today.
Yes. I’m a fan of institutional explanations, but most formal institutions are consistent with multiple equilibria.