Party system dynamics in post-war Japan: A quantitative content analysis of electoral pledges

Qualitative accounts of Japanese party politics allude to the standard left–right spectrum, but they invariably devote much more space to discussions of foreign policy differences than to socioeconomic conflict. Quantitative estimates of Japanese party positions treat short party responses to newspaper interviews as if they were true manifestos, and fail both to confirm the claims of the qualitative literature and to demonstrate any consistent basis for party differentiation at all. We address both puzzles by applying a text scaling algorithm to electoral pledges to estimate Japanese party positions on three major policy dimensions. Our analysis largely confirms the findings of the qualitative literature, but also offers new insights about party movement and polarization over time.