Structure and Behaviour: Extending Duverger's Law to the Japanese Case

Japan uses simple plurality elections with multi-member districts to elect its lower house. This system tends to produce competition among n + 1 candidates per district. This ‘law of simple plurality elections’ is a structural generalization akin to Duverger's Law. Evidence from Japan also indicates that the causal mechanism behind this ‘law’ is not strategic voting, although strategic voting occurs, but elite coalition building. It is further argued that the connection between structure and behaviour is learning and not rationality. Equilibria are reached slowly through trial and error processes. Once reached, the equilibrium is unstable because parties and candidates try to change it. Even without rational actors and stable equilibria, however, this structural generalization accurately describes the dynamics of electoral competition at the district level in Japan.