脫黨參選的賽局分析：其他政黨先行決策模型

Abstract

在台灣的選舉中，基於政黨內派系的競爭、黨內資源的分配不均、政見方向的分歧等因素，未獲提名者與黨內產生衝突的情形時有所聞，面對這樣的情況，對手政黨的決策者需做出應對，未獲提名者也需考量各項情況以決定是否脫黨參選。本文考慮未獲提名者面臨不知道他黨決策者型態之資訊不對稱情況下，利用賽局模型分析他黨決策者決定採取積極或消極行為後，未獲提名者是否脫黨參選之情形。根據求出的序列均衡，我們得知當未獲提名者可感受到其未脫黨而原政黨勝選後的利益時，未獲提名者更容易採取不脫黨參選之策略。另外，若他黨決策者採消極作為，未獲提名者也無法搶走其票源時，策略型的他黨決策者則更容易採取積極作為。

Due to the competition among party factions, unequal allocation in party resources and different political perspectives, it is a common phenomenon in Taiwan’s elections that un-nominated aspirant has a confrontation with their own party. Under this condition, the decision maker of other party has to make a response, and the un-nominated aspirant also needs to consider every circumstance in order to decide whether to renounce membership of party or not. Considering the situation that the un-nominated aspirant faces asymmetric information, this paper uses the game model to analyze if the un-nominated aspirant will run as candidate after other party makes aggressive or passive action. According to the sequential equilibrium, we conclude that when un-nominated aspirant can share the winning benefits with their own party, there will be higher possibility of choosing not to run as candidate for un-nominated aspirant. Moreover, when the decision maker of other party adopts passive action and un-nominated aspirant can’t take away votes from rival parties, it will be more likely for decision maker of other party with strategic type to act aggressively.