Terrorist tactics spread and decline through social contagion like other collective fads.

Evidence

Bandura (1973, pp. 215–216) has suggested that symbolic modeling may help to explain the surge and decline of terrorist incidents: “Social contagion of new styles and tactics of aggression conforms to a pattern that characterizes the transitory changes of most other types of collective activities: New behavior is initiated by a salient example; it spreads rapidly in a contagious fashion; after it has been widely adopted, it is discarded, often in favor of a new form that follows a similar course.” — John T. Jost and Jim Sidanius, Political Psychology, 4160

Categorization

• XREF: Relates to contagion/cascade dynamics in collective behavior and to Milgrom’s work on how behaviors propagate through social networks.
• SEED: A possible essay: ‘Terrorism as fashion’ — the rise and fall of attack modes follows fad cycles, which reframes how we predict evolutions of conflict tactics.