Abstract
The Japan Socialist Party (JSP) was not able to take power during the era of the 1955 system. Why was that? The most popular answer to this question is that the dominance of dogmatic liftwing socialists deprived the party of adaptability.
This paper examines many explanations about JSP's stagnation and decline, and proves that many of them, including the left-wing-dominance theory, are not sustainable. Thus, other causes of decline should be found out.
First, the paper focuses on the election campaign strategy of the JSP, which has not been well discussed yet. Socialists did not develop their own constituency organizations for some reasons, and failed to secure and increase their popularity among voters. In terms of coalition strategy and policy ideas, even most of left-wing socialists were far more flexible and realistic in the 1950s and early in the 1960s than often argued. But dogmatic leftists grew rapidly in the party, and defeated all the realistic factions in the middle of the 1960s. It is this power shift that deprived the JSP of its adaptability.
