Governments can consider war to be an effective means to further its ends. Germany under Hitler felt that by invading Poland it could gain land, and it didn’t feel the Allies would come to Poland’s defense.

Business interests can promote war. Defense industries thrive when their weapons have to be consumed.

The western US was won by warfare with the Indians. This war was not waged by government or by business interests, but by individuals. Settlers waged this war, despite governmental figures like George Washington being against the conquest of Indian lands.

War has been a constant of human history, and wars frequently result in dramatic power shifts.

Another example: the Thirty Years War. This created the modern nation state, with a strong central government. Primarily France under Richelieu was the beneficiery of the Thirty Years War, while what today we call Germany was left a powerless patchwork quilt of small provences.

Usually when a side goes into war, the prediction is that the war will be quick and victorious. The American Civil War is a great example–war was intentionally fought by the South to create a new country.

2 isn’t always valid…but it will work. Some wars aren’t started by the government’s incompetence…they’re started by revolutionaries that the govt. doesn’t hear anything about until three months post-occurence…*cough*Revolution?*cough*

It’s hard not to overlap on the 3rd one, human instinct covers so many things. I would suggest breaking it up into two parts somehow. I would say a third one was being the fact that there isn’t enough to go around for everyone. So people compete for it. Yet, that’s really the human instinct basically.