Insurgent extremity: A new lens for analysing insurgent ideologies

There is a widespread interest in the role of insurgent ideologies in civil war. However, the concept has been understood in a variety of ways, which are at odds with how ideology is conceptualised in political theory and election research. This results in fragmented theorising and a lack of systematic empirical insights. I argue that we should conceptualise ideology in a theoretically sound, and empirically measurable manner to enable quantitative research. Using a definition of ideology common in political science, I argue that we should reclaim the term extremism to theorise effects of insurgent ideologies. I conceptualise ideological extremity as an insurgent group's ideological distance to an average ideology. Instead of relying on ideology-specific arguments, this novel concept enables theorising and empirically studying the effect of extreme, compared to moderate ideologies in a generalisable way, allowing insights that are transferable to future ideologies. The concept maps onto a measurement model, enabling me to estimate insurgent's ideological extremity based on their manifestos.