傳統的研究智慧中，總統制和兩黨制的配套被認為是一個民主國家較容易運作的組合。主要的理由是兩黨制較不可能出現意識形態的極化，以及因為兩個政黨需要贏得中間位置的選票，其可以促成政黨之間較溫和及向心的競爭，因而有助於總統制的運作。然而，近年來，一些兩黨總統制國家發生嚴重的憲政危機，甚至促成民主衰退。為何這些兩黨總統制國家會走上民主衰退的道路，是本文所要探索的研究問題。首先，本文透過對於拉丁美洲兩黨總統制國家的個案分析發現，憲政結構的因素如總統和國會的權力抗衡會影響..

Past research argues that presidentialism and two-party systems are workable combinations that can facilitate democratic stability. The causal mechanisms are that ideological polarization is less possible to appear in a two-party system, that two parties needing to win votes from the center encourages moderation, and that the absence of the extremist parties and the centripetal nature of party competition favor democratic stability. However, in recent years, some presidential countries with a two-party system in Latin America..

受到越來越多新興民主國家制訂半總統制憲法的影響，對於半總統制的相關研究也越來越受到重視。依照學界對半總統制的定義，威瑪共和與芬蘭都在 1919 年設計出符合半總統制內涵的憲法，可說是當代最早的兩個半總統制的個案。這兩個國家的憲政運作卻有完全相反的結果:威瑪在 1933 年崩潰，而芬蘭先是渡過經濟危機，更在 80 年代逐漸往議會制轉型。本文擬就制度與非制度因素的互動，討論這兩個個案運作的迥異結果。本文將從憲法理論做比較的出發點，分析兩種不同理論基礎的半總統制憲..

As democratization spread in Eastern and Central Europe over the last two decades, Semi-Presidentialism has become a concept with more attention paid when discussing constitutional issues. By definition, the Weimar Republic and Finland were two of the initial experiments of semi- presidentialism. However, the constitutional practices in the Weimar Republic and Finland are worlds apart. Both semi-presidential, the Weimar Republic had broken down but Finland became a quasi-parliamentary democracy. This paper intends on discussi..