Twenty years ago Alberto Alesina and Enrico Spolaore published a much quoted article entitled “On the number and size of nations”. It was the time of the break-up of Communist-ruled “ethnically-based” federations and, on the other end of the continent, of European integration. The view underlying Alesina-Spolaore (A-S) paper was both simple and seemingly very persuasive. There are manifest advantages of sharing public goods as per capita costs of provision decrease with larger population size. Short of any countervailing costs, the optimal size of political organization would be a unified world. However, as people live further apart from each other and have different preferences, sharing public goods makes less sense: some prefer to invest more in defense, others in education, the third in religious schools etc. So, the optimal size of a state is where the two tendencies just offset each other: similar peoples will share a state, federation or confederation up to a point that dissimilarities in preferences take over.


The liberal nostrum reflected in A-S assumption (that similar people want to live together) had its corollary in the common misconception that one often hears even today, namely that ethnic or religious conflicts are somehow the product of lack of knowledge of the two communities about each other and that if people only spent more time with each other, the conflict would lose its raison d’être and dissipate.
I do not know what causes civil wars. I could write down a laundry list of things that seem to me to make its likelihood greater: economic hardship, youth unemployment, desire to find a scapegoat, inability to resist demagogues, interested minorities who have much to gain from war etc. Moreover, once a determined and violent minority within one group is able to create bloodshed, there is a natural tendency of the other side to react and then very soon the lines between the groups are drawn and those who refuse to join either side are the prime target for elimination by both groups. War thus feeds on itself.
This is not an elegant theory that can be set out in a model, but I think -–and I trust that this is something increasingly confirmed —that similar people are as likely to want to share a state as to be willing to split up or to go to war; and that believing conflict can be prevented by people knowing each other better is just an illusion.

タイラー・コーエンも、ブルームバーグ論説で似たような見解を示している(H/T 本人のMRブログエントリ)。

Sometimes a region wants to leave a country because of differences of ethnicity, religion, language or background culture, as is the case with the Scottish independence movement and the Catalonian secessionists. In those instances, it’s not obvious whether a unified or a newly independent government would result in greater liberty and prosperity. And for all the strong feelings you will find, I am not sure there is an objectively correct moral answer as to whether there should be one nation or two.
We do know, however, that political tensions rise and emotions tend to flare as such secessions approach the realm of possibility. For instance, there is a chance the government of Spain would react aggressively to what it perceives as an unconstitutional Catalonian secessionist attempt. Madrid might institute legal sanctions against Catalonian leaders or, in an extreme case, send in troops. The final result could be no independence and less liberty in all parts of Spain.
The problem is that people are often overly passionate about political boundaries, and an extra dose of irrationality isn’t exactly what the world needs right now. To cite another example of this problem, the Brexit referendum seems to have lowered the quality of debate and governance within the U.K.


  • リバタリアンの自己統治の考え
    • 中央集権による抑圧が行き過ぎれば、ある地域がより自由で民主主義的な政治に移行する、という点で、分離独立は圧制へのチェックの機能を果たす。ソビエト崩壊時のエストニアの独立が好例。
    • ただし、このリバタリアンの原理に沿わない、上述の民族等の差異に基づく分離独立の動きもある。
    • また、このリバタリアンの原理には、限界が設定されないという問題もある。
      • 仮にポートランドの7割の人がトランプ率いる米国から離れたいと思っても、分離独立が良い考えだとは思わないだろう。そのような考えが通れば、多くの政治単位が滅茶苦茶になってしまう。
      • 仮に1860年代に南部の独立が成功していれば、その新しい国では奴隷制が継続していただろう。
  • 保守的な考え
    • 政治的分離による圧倒的な恩恵が明確になる、もしくは、2つの集団が冷静に合意する(例:チェコスロバキア)、のいずれかの条件が満たされない限り、分離独立には反対するという考え。
    • この考えでは、スコットランドカタルーニャの独立は支持されない。
    • 米国の独立にこの考えを(愛国心は措いておいて)当てはめるならば、次のようになる。米国が大英帝国の一部に留まっていたならば、税は低く、奴隷制はもっと早く廃止されていただろう。それでも、遠距離からの英国による統治が安定的に長続きしたとは思えない。問題は、1776年が適切なタイミングだったかどうかだが、当時の米国の政治思想と指導者の質を考えれば、その答えはイエスと考えて差し支えなかろう。
  • 経済学の「オプション・バリュー」の考え
    • 分離か否かではなく、分離か事態の改善を待つか、という選択に置き換える。待つことの価値を考えれば、余程の圧政下にあるのでない限り、分離しない、という選択に落ち着くのが普通。