Tribalism as a Prisoner's Dilemma
It would be a salutory effort to look over the wars, revolutions and civil strife of the last sixty years and see how many of the participants got an outcome (taking account of war casualties and so on) better than the worst they could conceivably have obtained through negotiation and peaceful agitation. Given the massively negative-sum nature of war, I suspect the answer is “Few, if any”
Reflecting on the outbreak of peace in Aceh (and ongoing war in Sri Lanka), John Quiggan over at Crooked Timber asks whether war is worth it--and concludes, unsurprisingly, that it is not. That may be true enough but it's a separate question whether rational players can risk negotiation, peace-making, cooperation and other less costly policies where tribal patronage systems are entrenched.
In the tribal patronage system everyone takes care of his own--and no one takes care of anyone else. If members of your tribe are in power you, your family, and your village, get jobs, roads and other amenities; if members of competing tribes are in power you get nothing and on the worst case scenario, you and your kin are vulnerable to ethnic cleansing.
You cannot choose your tribe or opt out of the tribal system. Even if you are a liberal cosmopolitan by conviction, you will be identified as a Hutu or Tutsi, Serb, Croat or Bosnian, Sunni, Shi'ite or Kurd, Irish Catholic or Protestant and you will benefit from the system or lose out accordingly. So even if you are a liberal cosmopolitan, because you know the system is entrenched, and know that everyone else knows it too, as a rational chooser you are going to vote for your tribesmates and, if necessary, fight to see to it that they get into power. So will other rational choosers, by the same reasoning, even if they are liberal cosmopolitans too and would rather cooperate.
Sometimes, when the current tinpot dictator's regime gets too bad it becomes worthwhile for members of different tribes to form coalitions to get him out. But such coalitions are short-lived because the ethnic card is always in play. Once coalitions achieve their immediate ends it is played and it's back to business as usual.
I grew up in New Jersey under this tribal system where everyone took care of their own and no took care of anyone else or expected to be taken care of by anyone else. It was bliss to leave, to go to school in the Midwest, where at least some things were open and above board, where there weren't 1000 unwritten rules to negotiate or no-go areas to avoid, where there was at least the pretense of fairness and public-spiritedness. I never had any sympathy for my classmates who deplored the white bread homogeneity of the Midwest and effused about the wonderful local color of ethnic neighborhoods. It's all very nice to visit those Little Italys and Chinatowns to the extent that they're theme parks for the tourist trade, but real ethnicity, real tribalism is the root of most, if not all, evil. All that local color and ethnic food, both here and abroad, aren't worth it.