terrorism
Definition
Terrorism is a form of asymmetric intergroup conflict in which non-state actors use or threaten violence to further political, social, or ideological ends, typically against targets chosen to signal organizational strength, attract followers, and disseminate a message beyond the immediate victim. Lethality functions as a core performance metric for violent extremist organizations, reflecting both destructive capacity and strategic signaling, and annual death tolls have been shown to escalate across a leader's tenure, with leadership configuration shaping an organization's overall level of lethal effectiveness more than the rate of that escalation. A longstanding assumption in the field holds that terrorism is by definition ideologically motivated violence, yet a growing body of cases involving lone actors with no coherent or consistent ideology has placed that assumption under serious pressure. Some perpetrators, such as Axel Rudakubana, are recognized by police and judicial authorities as having pursued no political, religious, or racial ideological cause, suggesting that violence fixated on harm for its own sake may fall outside the conventional definition of terrorism even while qualifying as extremism. Hybrid or composite cases, in which individuals draw on multiple contradictory ideological sources, further complicate classification, with UK Prevent data showing the 'no ideology' referral category reaching nearly 5,000 cases by March 2025, dwarfing referrals for Islamist or extreme right-wing categories.
Sources: Harms et al. (2026), McCauley (2026), Cassam (2026), Baele (2026)
Related Terms
- salad bar extremism (4 shared articles)
- ideology (3 shared articles)
- salad bar (2 shared articles)
- extremism (2 shared articles)
- violence (2 shared articles)
- violent extremism (2 shared articles)
- political violence (1 shared article)
- online extremism (1 shared article)
- composite extremisms (1 shared article)
- fixation (1 shared article)
- mobilization frame (1 shared article)
- nihilistic violent extremism (1 shared article)
- group conflict (1 shared article)
- leadership (1 shared article)
- lethality (1 shared article)
- multilevel modeling (1 shared article)
Applications
Terrorism and Ideology
Ideology has historically been treated as a defining characteristic of terrorism, understood as the motivating framework that identifies enemies, selects targets, legitimizes tactics, and situates personal grievances within a broader political narrative. That equation is increasingly contested. Cassam distinguishes between ideologically driven terrorists and violence-fixated individuals whose commitment to harm fails to satisfy the necessary conditions of subject matter, generality, interconnectedness, and explanatory ambition required for a belief system to count as an ideology, meaning some perpetrators are recognizable as extremists without qualifying as terrorists under standard definitions.
Sources: McCauley (2026), Cassam (2026)
Terrorism and Leadership
Leaders of violent extremist organizations exercise disproportionate influence on organizational lethality by defining grievances, legitimizing violence, mobilizing followers, and shaping the group's external reputation through lethal attacks. Empirical analysis of 68 VEO leaders and 645 leader-year observations shows that the effect of a leader's power orientation on lethality depends entirely on their influence style: among charismatic leaders, a personalized power orientation was associated with roughly 65.65 predicted annual deaths compared to 5.28 for those with a socialized orientation, while among pragmatic leaders the pattern reversed.
Sources: Harms et al. (2026)
Terrorism and Radicalization
Radicalization research has long relied on ideology as the primary lens for understanding how individuals move toward political violence, but the category is proving insufficient for cases where the primary draw is violence itself rather than any coherent set of political beliefs. UK Prevent data show the 'no ideology' referral category reaching nearly 5,000 cases by March 2025, a pattern that raises questions about whether existing ideological frameworks can account for individuals who lack formal ties to any recognized extremist movement.
Sources: Horgan & Shayler (2026), Baele (2026)
