Either or? Reconciling findings on mental health and extremism using a dimensional rather than categorical paradigm

The background for this paper is the debate over what role mental illness plays in radicalization to violent extremism. While one camp points to cases of abnormal functioning of perpetrators, another argues that normal psychological mechanisms are central. Through a review of these perspectives, it becomes clear that mental illness cannot be ruled out as an epi-phenomenon, but is not a necessary condition either. The paper draws on work in psychiatric nosology on dimensional and categorical conceptions of illness and argues that the perspectives in this literature reflect a categorical approach to normal and abnormal functioning. Under a dimensional perspective, findings converge. The paper concludes by showing how this new dimensional approach to the role of mental illness in radicalization has implications for the design of risk assessment tools and leads to the recommendation for stronger inter-agency cooperation between mental health professionals, social services, and police and intelligence services.