合理的なスターリン
●Konstantin Sonin, “The dictator’s approach to electoral patterns”（VOX, August 9, 2008）
While the people of the developed world are fascinated by electoral campaigns, more than a half of the world’s population does not have a chance to participate in elections. Yet any dictator needs some popular support; the difference is that he can trim his constituency, eliminating those who do not support him.
Yet, one might see a rational motive behind the killing and imprisonment of millions of people. Unlike democracies, where politicians adjust polices to the median voter to be elected, brutal dictators might adjust their constituency by eliminating citizens who are in opposition to the regime.
Furthermore, within the model, we assume that the dictator chooses to act once the share of enemies in the population exceeds some critical limit at which he will be (or believes to be) at risk of overthrow.
Our model suggests that the number of eliminations depends on the probability of correctly identifying enemies, the number of enemies, and the “threat” that the enemy poses. Although we are unable to “prove” our model based on the stylised facts of the three repressions, we can show that the model is consistent with these facts. The model makes one prediction that is consistent with Stalin’s observed behaviour that is far from intuitively obvious. A rational dictator will deliberately eliminate innocent citizens and will eliminate more innocents when enemies are difficult to identify. Stalin’s slaughter of innocents is cited by historians as a sign of his mental derangement, but in our model it is the predicted behaviour of a dictator facing a binding revolution constraint.
選挙民の選好を所与として選挙民の多数派（＝正確には中位投票者）の同意を得られるような政策を打ち出すのが民主主義社会における政治家の行き方だとすれば（政治家が選挙民にすり寄る）、全体主義社会における独裁者は自らの選好に沿うような形で選挙民の構成に手を加える（executions and imprisonments of political enemies＝physical eliminations (execution, imprisonment or exile) or legal measures (disenfranchisement of voters or candidates)）ことによって結果として選挙民の多数から支持を得る（選挙民が独裁者にすり寄る、正確には独裁者の選好に強制的にすり寄せられる）ということになる（＝選挙民を強制的に入れ替えることによって中位投票者の選好を変える）。その典型がスターリンによる粛清。
上記論説中でも利用されているarchival dataに関する詳細は以下を参照。
●About the Soviet Archives Research Project（Hoover Institution）
（追記）
●Paul R. Gregory, Philipp J.H. Schroder and Konstantin Sonin, “Dictators, Repression and the Median Citizen: An “Eliminations Model” of Stalin’s Terror (Data from the NKVD Archives)（pdf）”（CEFIR/NES Working Paper No 91, November 2006）
