本文透過總統與總理在憲法上的權力，以及行政權內部互動關係，析論左右共治不同內涵。經由新興民主國家的案例檢視，本文企圖論證，論者所主張在府會不一致下「應」出現的「左右共治」運作類型，除了不是半總統制的「宿命」，亦因總統或總理「讓出」及「爭奪」行政權所存在的種種變數，使得這一類型的運作內涵變得更複雜難測。因此，在應然面與實然面之間，左右共治各種類型將有被指陳之必要，而透過不同的左右共治類型，半總統制研究將能經由行政權內部互動，更有效地解釋行政與立法關係穩定與否。

This paper will discuss various forms of “cohabitation” through the constitutional stipulations and intra-executive relationships between the president and the prime minister inherent in semi-presidentialism system. By examining the cases of newly democratic countries with semi-presidential systems, this paper seeks to demonstrate that many authors supposed “cohabitation” that should exist is not guaranteed in this system, and the operational types are highly complex and unpredictable, due to the many variables inherent in the “yielding” or “competing for” executive power between the president and the prime minister. Thus, between the “normative” and “positive” aspects, it is necessary to point out various forms of “cohabitation” in semi-presidential system and outline the details of the internal workings of the executive power based on the variables of goals and means of the president and the prime minister to explain executive-legislative relationship more effectively.

半總統制;左右共治;總統;總理;行政權

semi-presidentialism; cohabitation; president; prime minister; executive power