2004年3月

單一行動者預設與政黨、派系競爭理論的建立－以單記非讓渡投票制下的選舉為例
The Assumption of Unitary Actors and Theory of Party and Faction Competition under the Single Non-Transferable Vote

研究論文 Research Article

劉從葦
Tsung-Wei Liu

151-195

理性抉擇理論是方法論上個人主義的研究途徑，因此理性抉擇理論和單一行動者預設應該是不相容旳。從博奕理論的觀點來看，一群有共同利益的自利個人不必然會合作去追求他們的共同利益。從社會選擇理論的觀點來看，聚合一群理性個人的偏好所產生的集體偏好不必然是理性的。然而，理性抉擇理論者所建立的政黨競爭模型又大多預設政黨爲單一行動者，而使得其模型與研究途徑自相矛盾。另一力面，在理論測試上政黨位置的測量也有相同的問題。不論是專家調查或政見硏究小組的測暈都僅提供政黨在政策空間裏的單一位置，而沒有政黨內部分歧的相關資訊。理論的自我矛盾加上測量的不足，使得政黨競爭理論的重新檢視變得十分重要。集體行動與集體理性的問題使得在建立政黨競爭模型時必需考量政黨內部的分歧與衝突。可行的起始點之一為將派系競爭納入模型裏。本研究以單記非讓渡投票制下的政黨競爭為例來討論如何建立同時考量政黨與派系競爭的理論模型。除了理論的修正，政黨位置的測量也必須要能呈現政黨內部分歧的狀況，以避免理論與實證資料間的不相關而使得理論無法得到支持或被否證。本研究以台灣立法委員選舉為例，說明如何測量個別候選人的位置並將其聚合來分別呈現政黨丶派系的位置與同黨候選人在政策空間裏的分佈情形。

Rational choice theories are methodological individualism, so they are not compatible with the assumption of unitary actors. Game theorists argue that people who have interests in common would not necessarily cooperate. Social choice theorists demonstrate that preferences of collectives aggregated from individuals' preferences are not necessarily rational. However, parties are usually assumed to be unitary actors when rational choice theorists develop their models of party competition. This makes their models and approach contradictory. The measurements of party positions have the same problem. Both expert surveys and Manifesto Research Group provide party positions in the policy space without the information about intra-party conflicts. Therefore, it is crucial to rethink the theories of party competition and measurements of party positions. Because of the problems of collective action and collective rational­ity, intra-party conflicts must be considered when developing models of party competition. One of the possible starting points is to include factions into the models. Electoral competition under the single non­-transferable vote is used as an example in this research to show how to develop a model that includes both parties and factions. In addition to the revision of theories, the measurements of party positions should be improved to make the examination of models possible. This research discusses how to measure candidates, factions, and parties' positions in the elections of the Legislative Yuan in Taiwan and tests the theory against the data obtained.

理性抉擇理論, 顯著理論, 政黨位置測量, 單一行動者, 派系
rational choice theory, saliency theory, measurement of party position, unitary actor, faction

政治學
Political Science

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