政黨政治向來為研究憲政運作、民主深化的核心議題。過往的研究，多將政黨政治視為影響憲政與民主的自變項，但憲政特性以及民主轉型的過程，也可能系統性的影響政黨體系，對於政黨體系變遷的規模、機率，存在一定的關連性。基於此，本文以政黨體系變遷為依變數，從制度特性以及民主化背景來觀察政黨體系變遷的特性。核心假設有三：首先，就制度特性而言，直選總統的國家，比起議會內閣制的國家，政黨體系變遷的機率較高、規模較大；第二，以選舉時程而言，也是制度面向的因素，在直選總統的國家中，同時選舉或蜜月選舉，因為總統衣..

Party politics is an important issue to explain the constitutional work and consolidation of a democracy, and especially for newly democracies. If the party system would be affected by different types of constitutional systems and historical legacy, the party system should also be changed. We have three hypotheses: first, we suppose those countries with a directly elected president will have a higher probability for party system change. And the smaller parties are more likely out of parliament. Second, based on the coattail effect, countrie..

選舉制度影響政黨體系，是廣為人知的因果推論。依此邏輯，若以政黨體系為因，以選舉制度的變化為果，即產生內生性的選制變遷理論。然而，某些研究者仍認為選制變革起於和政黨體系無關的外生因素。本文主張，選制變遷是否受到政黨體系的影響，取決於選制的種類。第一，有利大黨的多數決選制如果始終未出現一黨過半，則國會屬於多黨制，有可能因為小黨組成多數聯盟而改採比例性選制。尤其當現狀為並立式單一選區兩票制時，可能因為小黨的議席多來自政黨名單，而比代表區域主義的多數決選制更容易導致..

It is well known that electoral system shapes party system. By this logic, an endogenous explanation for changes in electoral systems should treat party system as the cause and changes as the consequence, in sharp contrast with theories attributing changes to exogenous factors that are irrelevant to party system. This paper argues that whether changes in electoral system are caused by party system depend on the type of the electoral system. First, if a majority party never emerges from a majoritarian electoral system, minor p..