POL SCI: Rationalist Explanations for War

Wars are costly, and yet wars recur

• inefficient:
• -There are (ex-ante) bargains that could be reached, where leaders could gain the same final outcome with a negotiated settlement, while avoiding the costs of war

• -War caused by irrational people
• -Costs of war not suffered by leaders
• -Even rational leaders who consider the risks and costs of war may end up fighting (“rationalist explanations”)

• -Anarchy
• -Rational preventive war
• -The expected benefits are greater than the expected costs
• -Rational miscalculation/disagreement about relative power
• -Rational miscalculation due to lack of information

Not a sufficient explanation

Explanations fail to address the question of how or under what conditions it can be possible for two states both to prefer the costly gamble of war to any negotiated settlement

• -Two states: A and B
• -X = A’s share of the territory

• 0________________1 x
• iB iA

• -iA and iB: A’s and B’s ideal points
• -A’s utility = X
• -B’s utility = 1 – X
• -Assume both countries are risk neutral

• p = A’s probability of winning a war against B
• cA and cB = A’s and B’s costs of war
• -EUA(war) = p(1) + (1-p)(0) – cA = p – cA
• -EUB(war) = p(0) + (1-p)(1) – cB = 1 – p - cB

• -States know there is one true probability p
• -States are risk neutral or risk averse
• -A continuous range of settlements exists

• Rational miscalculation due to disagreement about relative power or lack of information:
• -Neither goes far enough/ works by itself

leaders have incentives to share private information

what would prevent them from sharing such private information

• withhold private information because they wish to obtain a favorable negotiated settlement:
• -Incentives to exaggerate their true willingness to fight or their true capability

Even when there is no private information (and both sides agree on the bargaining range), war occurs because one side cannot commit to uphold the bargaining

• -A large first strike advantage exists
• -When one side’s probability of winning in the next period exceeds its probability of winning in the first period
• -If the bargain would drastically increase one side’s future bargaining leverage