兼容並蓄或拼裝上路？－從內閣制與總統制優劣辯論檢視半總統制的利弊

半總統制是1990年代以來許多新興民主國家採行的憲政體制，新興民主國家採行半總統制後，往往會期待半總統制這種混合式的憲政體制，可以結合總統制與內閣制的優點，並迴避總統制與內閣制的缺點。然而，就某些半總統制國家的實際憲政運作來觀察，半總統制這種混合式的憲政體制，並不見得是結合了總統制與內閣制的優點，反而同時匯集了總統制與內閣制的缺點。我們可以問的問題是，相較於內閣制與總統制，究竟半總統制是一種兼容並蓄的憲政體制，還是一種拼裝上路的憲政體制？是什麼因素使得若干國家的半總統制能夠幸運地成了兼具總統制與內閣制之長的「結晶體」？相反地，又是什麼因素使得若干國家的半總統制不幸地成了兼具總統制與內閣制之短的「拼裝車」？本文希望以1990年代以來關於內閣制與總統制優劣的辯論為基礎，檢視並評估半總統制這種混合制的利弊得失。

關鍵字

半總統制；內閣制；總統制；總理總統制；總統議會制

並列摘要

Semi-presidentialism, a hybrid constitutional system from presidentialism and parliamentarism, has been adopted by many nascent democracies since 1990s, and is usually supposed to combine the advantages that presidentialism and parliamentarism have. However, looking into the actual constitutional practice of the countries adopting semi-presidentialism, this hybrid constitutional system may not integrate the advantages, but rather gather the disadvantages of presidentialism and parliamentarism. Here comes a question: compared with presidentialism and parliamentarism, is semi-presidentialism a beneficial combination or a detrimental mixture? Why can semi-presidentialism in certain countries fortunately be a benign composite which embraces the advantages of both presidentialism and parliamentarism, while in some countries it may unfortunately turn into a malign entity which possesses the disadvantages from both? This study hopes to inspect and evaluate the pros and cons of this hybrid constitutional system on the basis of the debates on advantages and disadvantages of presidentialism and parliamentarism since 1990s.