Are wars about anything, or just wars? In modern times, a reason of sorts is thought decorous, yes: Ruritania is threatening us, or might, or does something wrong, or Ruritanians don't think rightly about the gods. We must kill them. And yet everywhere in all times, almost miraculously, some reason for a war is found. It would seem that wars are not about anything, but just what we do.
Recently the collapse of the Soviet Union appeared to offer a prospect of extended peace. There seemed nothing left to fight about, at least on any scale. Yet the United States quickly launched a half dozen wars of no necessity and threatened others. Why?
Because wars are what we do.
It may surprise many people to learn of evidence for a genetic foundation of human behavior. This should not be surprising. Dogs form packs, mark territory, and bark furiously at strange dogs. So, it seems, do people. An empire is just the result of these canine instincts.
Consider conservatives, as they are more relevant to the fighting of wars. (Liberals appear as genetically determined,)
Conservatives tend to be tribal, intensely loyal to their group–race, country, ethnicity, religious faith–which in national terms becomes patriotism. They lack empathy. They see the world in terms of threats, conflict, and dominance. They favor capitalism and the Second Amendment, revere the military, speak of blood and soil, oppose taxation of themselves to give to the less fortunate.
An important point here is that these traits clump together, although there is no logical connection. For example, one might rationally favor ownership of guns as necessary to self-defense yet oppose having a large military as unnecessary. One might favor a large military in what appeared a dangerous world, yet favor extensive governmental charity as what one might see as common decency.
Yet this almost never happens. If you tell me that you oppose abortion, with confidence I can predict that you fit the description above of a conservative. If you tell me that you oppose the Second Amendment, I can be pretty sure that you favor abortion, acceptance of immigrants, marriage of homosexuals, and so on.
We all have access to the same information about the world, to the internet, the same books and newspapers, and we all live in very much the same society. Yet liberals and conservatives arrive at sharply differing conclusions from identical evidence. This suggests an innate predisposition.