Radicalizing alone: Are “lone wolves” idiosyncratic, political entrepreneurs or aggrieved avengers?

The increasing prominence of lone actor political violence has led scholars to ask what radicalizes individuals to lone violence. Three competing theories have arisen. The first argues that violence is driven by isolated and idiosyncratic circumstances. The second argues that lone actors are political entrepreneurs initiating coordination with like-minded individuals through violence. The third argues these attacks are systematically driven by local and national grievance events, where assailants are avenging the grievance event. I examine the Palestinian wave of lone actor attacks during 2015–2016 which includes over 330 attacks. The findings indicate that these are systemically associated with grievances committed by Israelis. Specifically, when Palestinians are killed, this causes the number of lone actor attacks to increase. The article concludes that lone actors are neither idiosyncratic, nor are they political entrepreneurs. Instead, lone actor attacks serve as an expressive political act, with individuals radicalizing alone by systematically avenging both national and local grievances.