Why do weapons sustain durable peace in some societies but provoke perpetual violence in others? We develop a theory in which the value of human life and the frequency of violence are jointly determined by weapons technology and economic conditions. Lethal weapons deter conflict but raise mortality, taxing the future returns to investing in one’s livelihood. When those returns are high, deterrence dominates and peace and investment reinforce each other. When those returns are low, the mortality tax dominates, agents divest from the future, the value of life falls, and violence deepens, a trap that deadlier weapons worsen. Whether weapons pacify or destabilize depends on the interaction between their offensive characteristics and the baseline prosperity of the society they enter. The theory illuminates four historical episodes: how Medieval Iceland (930–1262) sustained stateless order without a sovereign; why Tokugawa Japan (1603–1868) contained firearms within an institutional order that sustained two centuries of peace and growth; why firearms traded into West Africa and among Native American nations (17th–18th century) produced escalating violence and persistent underdevelopment rather than deterrence; and why the Comanche of the southern plains (c.~1750–1850) rose to regional dominance on horse and gun complementarities and then collapsed as sustained raiding into northern Mexico hollowed out the prosperity base on which their own order depended. The model also refines the logic of nuclear deterrence and generates testable predictions about urban gun violence in high-poverty neighborhoods.

That is from a new paper by Samuel Lee, Ilari Passivirta, and Alexander Zentefis, via the excellent Kevin Lewis.