What are fundamentalist beliefs?

Fundamentalist beliefs are often discussed in relation to extremist, radical, or fanaticist beliefs, or terrorist ideology, as well as in relation to terrorism, radicalization, and violent extremism. Besides, the notion is frequently defined and operationalized, for example in the field of psychology. Despite the frequent recurrence of the notion in the literature, no clear and agreed-upon definition exists. Elements and characteristics that are commonly thought of as constituting fundamentalist beliefs are intellectual vices such as closed-mindedness or dogmatism, certain group dynamics and affections, a high degree of certainty in holding these beliefs, and fundamentalist content. Drawing on, among other things, recent developments in (social) epistemology, these alleged elements are critically reviewed. Based on this review, we develop what we call the Content-Reaction-Affect account of fundamentalist belief. This account, it is argued, is not only accurate, precise, fair, and clear, but also theoretically and practically fruitful.