Assessing Policy Congruence: Catch-all versus Ideological Parties. The Study of the Portuguese Party System

Most of the research on party political congruence has been skipping a fundamental aspect to a better understanding of this topic: the explanation of its causality. Tapping the main methodological approaches to the assessment of policy congruence, the article aims to test the importance of the political party type in explaining the levels of intra-party congruence. Following the literature on the issue, a comparison between catch-all and ideological parties is carried on. The study focus on the Portuguese party system and makes use of a set of 19 policy issues (plus left-right position). Additional to being a seldom studied case, even in comparative terms, the focus of the study on the Portuguese party system is used to clarify the importance of two explicative and conflicting perspectives over party congruence: catch-all parties are more congruent than ideological parties; and ideological parties are more congruent than catch-all parties. Opposing to other previous research, findings on the Portuguese MP-voter linkages has pointed to higher congruence in the most central parties comparing to the most ideological parties (Belchior, 2008; Freire and Belchior, forthcoming). This raises a question: these results on the Portuguese case are conditioned by the measures that were used? And thus using other measures different results would be found? To answer it we propose to assess the level of MP-electors congruence within political parties, using different measures of congruence covering the most important methodological perspectives over the measurement of congruence. The findings of this research are also expected to contribute to a better understanding of policy congruence and especially of the importance of the use of different measures in its results. Besides corroborating previous research that point that policy issues anchored in the left-right dimension produce higher levels of MP-voter congruence, our findings support that the Portuguese catch-all parties (PS and PPD/PSD) tend to show higher levels of MPs-voter congruence than the other more ideological parties.