n : the doctrine that irredenta [regions that are related ethnically or historically to one country but are controlled politically by another] should be controlled by the country to which they are ethnically or historically related (from dictionary.com). a few examples should make it clear that irridentism is the primary cause of war. people will continue to describe other causes of war, but wars having nothing to do with irridentism are so rare that these other reasons are relatively unimportant.
i'll start with the exception that's currently foremost in my mind: america's most recent war against iraq. this had nothing to do with irridentism. america didn't attack iraq because of any ethnic or historical ties to the nation. the reasons given by the american government are various and changing, but the reason for the american people, who are ultimately responsible for the wars our government wages, was clearly revenge (or "justice", if you prefer). 70% of americans believed iraq's leader was responsible for the 9/11 attacks on america.
which brings us to 9/11. it was not exactly a war, but it had basically the same effect, and was caused by irridentism. there are certainly other causes, but i don't think the attacks would have happened if there wasn't a belief among the members of al qaeda that america had too much control over saudi arabia - a land full of ethnic and historic ties to al qaeda. if you doubt this, read osama bin laden's own reasoning for his actions.
now on to the seemingly endless conflict between israel and palestine. the position of both sides in this case is irridentism, and this is precisely why this conflict has continued for so long with so little movement toward peace. both sides have ethnic and historic ties to the same land, and both believe they are the rightful authority over that land.
the list of irridentism-caused conflicts is long: ireland, china/taiwan, china/tibet, north korea/south korea, serbia, india/pakistan, russia/chechnya, and so on. so if i'm right when that stopping irridentism would stop most wars, stopping irridentism is an incredibly important goal. so how do we do it?
this part i'm not so clear on, but it occurs to me that irredenta may not be considered in need of saving through war if it was clear that the people had the means to choose their own government. that is to say that democracy may be the best cure for irridentism. you could argue that israel is a democracy and this hasn't helped much in that case, but i'd respond that israel is not a democracy for the non-israeli people living in the disputed territories, who don't have the right to vote to give these territories to palestine. i think this right, whether or not it was exercised, would do much to end palestinian irridentism. in the same way saudi arabian democracy would do much to end al qaeda's irridentism, tibetan democracy would have weakened china's irridentism, and so on. democracy isn't a perfect antidote for irridentism and the wars it causes, but it's a good start.