The moral–emotional foundations of political discourse: a comparative analysis of the speech records of the U.S. and the Japanese legislatures

There is a growing body of research that focuses on the supposedly close association between an individual’s moral–emotional behavior and his/her political ideology. A prominent example is Haidt’s “moral psychology,” which claims that political liberals and conservatives draw on mutually different sets of moral foundations. However, this and other arguments, which have mostly been advanced in the social context of the United States, lack a comparative perspective. In this study, we examine these arguments in broader spatio-temporal settings by way of a comparative analysis of public deliberations in the U.S. and Japanese legislatures. More specifically, with the help of well-established moral- and emotional-word dictionaries, and employing advanced computational techniques for systematic data collection, we analyze a large volume of speech data that records floor debates over decades in the U.S. Congress and the Japanese Diet to derive longitudinal moral–emotional dynamics. We then use multilevel modeling to regress the derived moral–emotional patterns of legislative deliberations in each country on various covariates to locate possible drivers of these patterns. The results of these analyses reveal more qualified relationships between a moral–emotional framework and political ideology than preceding arguments have suggested, casting serious doubt on the widespread tendency in the literature to quickly rely on an ideological explanation. The findings suggest the need for a more comprehensive approach to handling moral–emotional phenomena in political science.