国家形成過程のゲーム分析

「交渉力モデル」のモンゴル帝国型遊牧国家への応用

抄録

In this paper, I demonstrate “the bargaining power theory of the state” presented by Ueda(2008, 2009) is applicable to nomadic societies. Ueda (2008, 2009) presented the “bargaining power theory of the state” based on historical and archeological studies of irrigation societies that there existed not only intra-society trades but also inter-society trades before sate foundation. I can summarize the main hypothesis of this theory as follows: (1) Irrigation societies can be modeled with hierarchical cooperation game.
(2) Intra-society trades within irrigation societies can be characterized as the structure of “infinite repeated game” and have a stable nature.(3) If the preceding irrigation societies often fell into disadvantageous positions in intersociety trades with supplier of necessary goods e.g. iron resources owing to weak bargaining power, the chiefs of irrigation societies were motivated to organize a state organ with a regular military force to make themselves more advantageous positions in the intersociety trades.(4) If the payoff of the chiefs of irrigation societies with regular military force is larger than the payoff of the chiefs of preceding irrigation societies without regular military force, then the chiefs of preceding irrigation societies transform them into a state.
The origins of nomadic state have been explained by the “predatory theory of the state”. However, there exist some counterexamples in human histories, e.g. cooperative activities among nomadic tribes for predatory activities. These cooperative activities must be organized by leaders of the nomadic societies for organizing military forces, that is, some state must be formed before the “predatory state” is formed in nomadic societies. The traditional predatory theory of the state never bridges the gap between the theory and these historical facts. In this paper I demonstrate that above four characteristics of “the bargaining-power theory of the state ” are applicable to nomadic societies and the origins of nomadic state are explained by this theory consistent with historical and archeological studies.