Party membership motivations and political activism in a polarized new democracy: Evidence from South Korea

This study investigates party membership motivations in South Korea, a highly polarized new democracy, and how they distinctively shape intra-party and campaign participation. Using survey data from 1,410 Democratic and People Power Party members, we evaluate the General Incentives Model alongside negative partisan motivation. Results show that while altruism is the primary reason for joining, higher affective polarization significantly intensifies negative partisan motivation, making it a key membership driver, particularly among conservatives. Crucially, engagement mechanisms are not monolithic: selective benefits predict both forms of participation, whereas collective policy motives specifically foster campaigning. Conversely, social norms motivation deters visible campaigning due to polarization-induced cross-pressures. Furthermore, negative partisan motivation reduces routine intra-party engagement without increasing campaign involvement. Ultimately, membership surges driven by out-group hostility produce “detached members,” indicating that expanding party rolls in polarized contexts does not automatically deepen democratic participation or organizational capacity.