Lack of Competition in Elections:A Consideration of Equilibrium and Rational Choice Theory

Abstract

無投票の選挙や，投票は実施されるものの事実上当選者が決まっている選挙は，“非競合的な選挙”だといえる．有権者には有効な選択肢が提示されないため，規範論的研究や政治評論の観点からは，非競合的な選挙は避けられるべきとされるのが一般的である．これに対し本稿は，選挙における〈均衡〉という概念と，投票行動に関する有力なモデルとしての合理的選択理論に着目する．規範論を脇に置いた価値中立的な立場から非競合的な選挙をみたとき，いかなる解釈・考察ができるかを議論する．具体的には，〈均衡〉の概念と〈M＋1法則〉，〈有効候補者数〉等の各種指標を比較・整理する．そのうえで，非競合的な選挙が現出しているという現実に既存の政治研究は追いついておらず，概念の整理や分析枠組みの整備がいまだ途上の段階にあることを示す．An election in which voting does not occur or in which the outcome is pre-determined, can be called a “non-contested election.”From the perspective of normative studies and political commentary, non-contested elections are generally regarded as undesirable, since voters are not presented with valid options. This paper focuses on electoral ‘equilibrium’ and rational choice theory as a leading model of political behavior and voting behavior. Rather than adopting a normative stance, this paper examines how to consider and interpret non-contested elections by the concepts of ‘equilibrium’ and the rational choice theory, whose prominent feature is value neutral. In this paper, ‘M＋1 rule’ and ‘effective number of candidates’ are referred, compared and reinterpreted. Lastly, this paper shows that existing studies by political scientists have not yet clearly defined concepts nor properly completed analytical frameworks of non-contested elections.5othe