Van Prooijen, J.-W., & Krouwel, A. P. M. (in press). Extreme political beliefs predict dogmatic intolerance. Social Psychological and Personality Science.


Dogmatic intolerance—defined as a tendency to reject, and consider as inferior, any ideological belief that differs from one’s own—is often assumed to be more prominent at the political right than at the political left. In the present study, we make two novel contributions to this perspective. First, we show that dogmatic intolerance is stronger among left- and right-wing extremists than moderates, in both the EU (Study 1) as well as the US (Study 2). Second, in Study 3 participants were randomly assigned to describe a strong or a weak political belief that they hold. Results revealed that compared to weak beliefs, strong beliefs elicited stronger dogmatic intolerance, which in turn was associated with willingness to protest, denial of free speech, and support for antisocial behavior. We conclude that independent of content, extreme political beliefs predict dogmatic intolerance.