Supposedly, we have too many wars due to overconfidence and related biases. In the latest American Journal of Political Science, Erik Gartzke says capitalism explains peace better than democracy: It is widely accepted that democracies are less conflict prone, if only with other democracies. … Economic development, free markets, and similar interstate interests all anticipate a lessening of militarized disputes or wars. This "capitalist peace" also accounts for the effect commonly attributed to regime type in standard statistical tests of the democratic peace.
Some other theories I've heard are that having a McDonald's reduces the likelihood of countries going to war with each other (this hadn't happened until the U.S bombed Serbia) and the "Greens Peace" theory that countries with some standard of golf courses don't go to war with each other. I've heard it was empirically shown that young democracies are especially likely to go to war. Hans Herman Hoppe was probably happy to hear that, eagerly anticipating that we would come to our senses and bring back monarchy. Samuel Huntington presented some interesting data on conflict in Clash of Civilizations, which if you don't feel like buying or borrowing you can see in this excerpt I shamelessly distributed to freeloading cyberspace-cadets here.
Some other theories I've heard are that having a McDonald's reduces the likelihood of countries going to war with each other (this hadn't happened until the U.S bombed Serbia) and the "Greens Peace" theory that countries with some standard of golf courses don't go to war with each other. I've heard it was empirically shown that young democracies are especially likely to go to war. Hans Herman Hoppe was probably happy to hear that, eagerly anticipating that we would come to our senses and bring back monarchy. Samuel Huntington presented some interesting data on conflict in Clash of Civilizations, which if you don't feel like buying or borrowing you can see in this excerpt I shamelessly distributed to freeloading cyberspace-cadets here.