憲政體制與選舉制度的優劣無疑是政治制度研究的重要議題。然而,論者經常是將這兩個議題彼此切割,單獨探討各種憲政體制或選舉制度的優缺點。本文強調,憲政體制與選舉制度這兩種政治制度應該搭配在一起進行觀察,才有可能明確判斷一個國家究竟應採何種憲政體制和選舉制度較適宜。由於不同的選舉制度會塑造不同的政黨體系,不同的政黨體系與憲政體制搭配在一起會組合成不同的政府型態,而不同的政府型態則會各自展現出正面與負面的政治效應,因此本文即是以「憲政體制」、「選舉制度」、「政黨體系」、「政府型態」四個變項所形成的分析架構爲基礎,探討不同憲政體制與選舉制度搭配下所可能造成的利弊得失,並對未來台灣在憲政體制與選舉制度的制度選擇提出粗淺的建議。就台灣的憲政體制走向而言,假若台灣未來的憲政體制將走向總統制,在立委選舉制度上應避免採取比例代表制或聯立制,以避免陷入政治僵局;假若台灣未來的憲政體制仍維持雙首長制,而立委選舉制度擬採取比例代表制或聯立制,則應設定政黨可分配席次門檻,以防止小黨林立造成政治不穩定,同時也應賦予立法院閣揆同意權,以避免出現缺乏施政效率的少數政府。
The contrasting impacts of different constitutional and electoral systems are undoubtedly important issues in the research of political institutions. Existing studies usually consider the advantages and disadvantages of each constitutional or electoral system separately, and ignore the fact that the two systems are in fact embedded together. This paper argues that the most appropriate constitutional and electoral system for a country can be discovered only when the two systems are considered together. Each electoral system produces a different party system, and each combination of party system and constitutional system also brings about a different form of government with its own positive and negative political effects. This paper investigates the strengths and weaknesses of different combinations of constitutional and electoral systems on the basis of an analytical framework consisting of four variables: the constitutional system, the electoral system, the party system and the form of government. Based on this framework, the paper also makes some suggestions regarding Taiwan's constitutional and electoral reforms in the future. If Taiwan's constitutional system moves towards presidentialism, in order to prevent political deadlock the legislature should not adopt a proportional representation system or compensatory two-vote system. If Taiwan retains a semi-presidential system and a proportional representation system or compensatory two-vote system is adopted for legislative elections, then a minimum vote threshold should be put in place to prevent the emergence of an atomized multi-party system, which may result in political instability. At the same time, the Legislative Yuan should be granted the power to approve nominations for the position of premier in order to guard against the emergence of inefficient minority government.