Individual level factors--Ethology is study on how humans and animals are equal.
They contend that humans have the instinct to fight like animals do. Fighting
would come when territory is intruded upon, for example. Frustration-aggression
theorists contend that an environment would frustrate a person, and then
aggression comes about. State Level--The type of political system is very
important. Democracies seem to be more peaceful while authoritarian/totalitarian
ones are more aggressive. Free trade also plays a factor with the commercial end
of a country does not want to deal with warring countries, thus making the
government slow down on wars with anyone, or slow relations with these warring
states. Nationalism is also a factor because it could result in ethnocentrism
and aggression could result from this. Protectionism (protecting goods and
services from one's own country with tariffs and government restrictions) could
also lead to war. International level--Problems could result from the system in
which foreign policy is conducted. This would be an anarchy system. The long
cycles theory comes into play here too. A balance of power could also lead to
war like in Europe in the 19th and 20th centuries.