Rethinking dominant party defection: The dual coalition dynamics of factional defection in post-war Japan (1945-2003)

Abstract

A key puzzle persists in party politics: Why do legislators defect from a dominant party? Using a fresh approach of nested games with factions as the unit of analysis, this thesis argues that factional defection from a dominant party occurs if key factions are marginalized in the inter-factional coalition game within the intra-party arena, and if they expect to win the future inter-party coalition game within the inter-party arena by forming a new government with the opposition parties. The thesisa?? main contribution is the validating of a model that integrates the inter-party coalition dynamics (the focus of the coalition literature) and the intra-party coalition dynamics (the focus of the party defection literature). This provides a fresh perspective of dominant party collapse through factional defection and LDPa??s one-party dominance. Using analytic narrative with cases from post-war Japan (1945-2003), this thesis provides an alternative perspective to understanding significant Japanese political events.