覇権安定の評判ゲーム理論

抄録

According to the orthodox theorists of hegemonic stability, for example, Kindleberger, Gilpin and Krasner, a hegemon has to have enough power and power bases to stabilize the international systems. If the hegemonic power and power bases decline, the international systems will be unstable. In hegemonic declining ages, however, if there is asymmetric information for the hegemonic power between the hegemon and the nonhegemons, it is possible that the hegemon stabilizes the international systems. According to Alt, Calvert and Humes, one of conditions for it is that the hegemon has enough reputation for the hegemonic power.
We construct a model of hegemonic stability by a reputation game theory of asymmetric incomplete information and explain some conditions of stabilization of the international systems in hegemonic declining ages. Our model is different from Alt, Calvert and Humes' one in these points. First, we distinguish the hegemonic international regimes (rules of coordination) and the hegemonic power (structure to keep rules). Secondly, we introduce discount factors for future expected payoffs of the hegemon and the nonhegemons.
We can get some results different from Alt, Calvert and Humes. First, we can explain an important relation between the hegemonic power and the hegemonic international regimes. That is, the hegemonic regimes are not sufficient conditions in themselves for the nonhegemon's coordination and the hegemonic power is needed to keep it. And the hegemonic power is not a neccessary condition for the coordination. That is, even if in hegemonic declining ages, the international systems are stabilized if the hegemonic reputation of power is established enough. Secondly, by introducing discount factors, we can explain some conditions under which the nonhegemons coordinate to stabilize the international systems even if the hegemonic reputation of power is not established enough.