There Won't Be War - Harry Harrison A bracing antidote to Pournelle's There Will Be War series.

As I recall, though, my biggest problem with many of the stories that our avoiding the scourge of war depended upon fundamental changes in human nature - i.e., we would have to become something other than human to escape it. Perversely, considering my usual pessimism regarding the species, I wanted to see stories where people created peaceful societies without having to genetically modify themselves or in some other way become nonhuman.