I just saw Errol Morris' The Fog of War last night. Robert McNamara ended that movie by iterating his belief that wars will always happen because its part of human nature. But really it seems to me that its not human nature to want war, but rather the nature of those in power. Along these lines, Herman Goering had a much more a prescient insight into war:
"Of course the people don't want war. But after all, it's the leaders of the country who determine the policy, and it's always a simple matter to drag the people along whether it's a democracy, a fascist dictatorship, or a parliament, or a communist dictatorship. Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the pacifists for lack of patriotism, and exposing the country to greater danger."
-- Herman Goering at the Nuremberg trials