政府體制、選舉制度和選舉時程－政治制度如何影響國會大選中的策略投票

Government Structures, Electoral Systems, and Electoral Cycle: How Political Institutions Affect Strategic Voting in Parliamentary Elections

李鳳玉(Feng-yu Lee)

《臺灣民主季刊》 18卷3期 (2021/09) Pp. 1-47

摘要

本研究探討政府體制、選舉制度和選舉時程對於國會選舉的策略投票的影響。透過對全球39個民主國家總計104個國會大選的民調資料的分析，本研究發現，雖然策略投票也會發生在採取非單選區相對多數決制的國家，但是一般說來，單選區相對多數決制的策略投票仍然較為普遍，只有一個情形例外，也就是當「採取非單選區相對多數決制的國會大選和採取相對多數決制的總統大選是同一天舉行」時，雖然國會選制是非單選區相對多數決制，但由於總統大選和國會大選同一天舉行，總統選制也會影響選民投票選擇，因此在這種制度組合下，選民在國會大選進行策略投票的比例還是相當高。作者綜合對政府體制、選舉制度和選舉時程效果的分析，得到以下幾點發現，首先，下列幾種制度組合的國家，選民最不會在國會大選中進行策略投票：（1）內閣制＋國會選制為非單選區相對多數決制；（2）總統選制為絕對多數決制＋國會選制為非單選區相對多數決制；以及（3）總統選制為相對多數決制＋國會選制為非單選區相對多數決制＋非同時選舉。其次，擁有以下制度組合的國家，選民最常進行策略投票：總統選制和國會選制皆為單選區相對多數決制。最後，在以下兩種制度組合的國家中，選民策略投票的比例居中：（1）內閣制＋國會選制為單選區相對多數決制；以及（2）總統選制為相對多數決制＋國會選制為非單選區相對多數決制＋同時選舉。

關鍵字

策略投票 ； 政府體制 ； 選舉制度 ； 選舉時程

並列摘要

This study investigates the impact on strategic voting in parliamentary elections of government structures, electoral systems, and electoral cycle. Through the analysis of survey data on voter choice from 104 elections in 39 democratic countries, this study finds that although strategic voting also occurs in countries that adopt a non-first-past-the-post system, it is generally more common that voters cast strategic votes in countries that adopt a first-past-the-post system. There is only one exception that countries adopt a non-first-past-the-post system in parliamentary elections, but still show a considerable level of strategic voting. This happens in non-parliamentary systems whose presidential elections use a first-past-the-post system, and are held concurrently with parliamentary elections. The reason why this institutional configuration leads to a considerable level of strategic voting in parliamentary elections is because, in concurrent elections, both the electoral systems of presidential and parliamentary elections would affect voter choice. Based on the analysis on the impact of government structures, electoral systems, and electoral cycle, the author has the following findings. First, the proportion of strategic voters is smallest in countries with one of these three institutional configurations: 1) parliamentary democracies whose parliamentary elections use non-first-past-the-post systems, 2) non-parliamentary democracies whose presidential and parliamentary elections use runoff and non-first-past-the-post systems, respectively, and 3) non-parliamentary democracies whose presidential and parliamentary elections use first-past-the-post and non-first-past-the-post systems, respectively, and are held non-concurrently. Second, the proportion of strategic voters is largest in non-parliamentary democracies whose presidential and parliamentary elections both use first-past-the-post systems. Last, the proportion of strategic voters is in the medium level in countries with one of these two institutional configurations: 1) parliamentary democracies whose parliamentary elections use first-past-the-post systems, and 2) non-parliamentary democracies whose presidential and parliamentary elections use first-past-the-post and non-first-past-the-post systems, respectively, and are held concurrently.

並列關鍵字

strategic voting ； government structures ； electoral systems ； electoral cycle

參考文獻

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