There are two approaches used to detect the people's political polarization in the literature. One is to locate people on the spectrum of ideology in order to calculate the distances among them regarding their positions on issues. The other is to measure the people's affective attitude towards parties. Regardless of which approach is adopted, the political polarization undoubtedly has both a positive and negative influence on democracy at the same time. This study argues that the affective polarization of partisanship exists among the people of Taiwan and should negatively influence the evaluation of the working of democracy, and even destabilize the people's democratic beliefs.

In order to verify the above arguments based on the social identity theory, the concept of social distance was used to measure the people's partisan polarization and to detect its influence on political attitudes toward democracy. The findings of the research are as follows. First, the study both reliably and validly measures the affective polarization of partisanship based on the concept of social distance. Second, the majority of the KMT's and DPP's supporters are characterized by affective polarization, especially the KMT's supporters, whose level of polarization is higher than that of the DPP's supporters. Third, partisan polarization negatively influences the working of democracy but does not erode the people's democratic beliefs. To sum up, although this research provides a relatively positive message for the working of democracy in Taiwan, the affective polarization of partisanship among the people should be prevented from rising continually to enable the democratic processes to function smoothly.