本文將半總統制運作的研究焦點置於總統與總理互動關係上，經由其「爭奪」行政主導權、或者「分享」行政主導權等不同變項，勾勒出更詳細的行政權內部互動關係；並且，透過幾個重要半總統國家案例之檢驗，本文更期望能解釋並預測不同半總統制運作類型的內涵及其變遷可能方向。本文企圖論證，半總統制在行政權運作上的雙元性特徵，以及其中總統與總理的競合關係，將是半總統制如何運作的最重要因素。

This paper focuses on the interaction between the president and the prime
minister, outlining the details of the internal workings of the executive, based on the variables of whether the president and the prime minister “compete” for executive power or rationally “yield” executive power. By examining the cases of countries with semi-presidential systems, this paper aims to explain the implications and predict the potential direction of transition in various forms of semi presidentialism. This paper seeks to demonstrate that a dual-executive inherent in semi-presidentialism, as well as the competition/cooperation between the president and the prime minister, are the most important factors determining how semi-presidentialism operates.