Electoral system effects and ruling party dominance in Japan: A counterfactual simulation based on adaptive parties

Japan's electoral system has long been held to be a primary shaper of party success and failure in Japanese politics. This paper offers a counterfactual simulation of electoral outcomes under Japan's long used SNTV/MMD electoral system. Because of features particular to the SNTV/MMD system, we are able to simulate party adaptation to alterations in the system and estimate what features of the system aided the longtime ruling Liberal Democratic Party's (LDP) success. Based on this new analysis, we find that it is an overstatement to hold the electoral system responsible for longtime LDP dominance.