The non-linearity between populist attitudes and ideological extremism

Abstract The relationship between populist attitudes and ideological orientations remains an area of considerable academic interest, yet much is still unknown about the ideological inclinations associated with populist attitudes. While many scholars acknowledge the link between populist attitudes and political ideology, existing studies often treat this relationship as either a given or a peripheral concern. This paper represents an initial exploration into the association between populist attitudes and political ideology. Utilizing data from the fifth wave (2016–2021) of the Comparative Study of Electoral Systems, which encompasses 43 countries and 52 elections, this study aims to uncover how this relationship manifests cross-nationally. By employing a variety of rigorous methodological models, including the Generalized Additive Model, our results reveal a nonlinear relationship between populist attitudes and political ideology. Specifically, we find that political ideology and populist attitudes exhibit a U-shaped nonlinear relationship and that ideological extremism and populist attitudes demonstrate an exponential nonlinear relationship. These findings emphasize the nuanced interplay between ideological positions and populist attitudes, providing a deeper understanding of how they intersect.