Explaining the diffusion of radical ideas

Growing interest in the diffusion of radicalism reflects concern with political discontent and widening social inequality. It also reflects the profoundly different forms of communication emerging from the new digital media environment that are recasting radical politics. Sociology has important and longstanding insights into the incubation of radical ideas and the inception of radical movements. Drawing on general network models, particularly threshold network diffusion models, we argue for a compelling perspective on the diffusion of radicalism that is emerging in contemporary sociology. Studying the spread of radical ideas contributes to the development of the diffusion literature by underscoring the limitations of static and singular network explanations—explanations that examine one network and one direction of influence at time. We contend that scholars should distinguish between the limited diffusion of radical ideas and the widespread diffusion of radical ideas. To explain the latter, network theories should integrate frameworks of multiplex networks and network ecosystems, as illustrated by research on the rise of radical right-wing political rhetoric. We consider how sociology might inform strategies for containing radicalism before drawing conclusions about future conceptual and methodological directions in research on radicalism.