Explaining Rare Acts of Violence: The Limits of Evidence From Population Research

After the tragic mass shooting in Tucson, experts struggled to explain why such horrific events occur, in order to prevent them in the future. The author argues that homicides perpetrated with firearms against strangers by individuals with mental disorders occur far too infrequently in the population to allow explanatory statistical modeling and predictability. However, from a public health perspective that seeks to reduce violence in populations, it is likely that efforts to improve treatment access, continuity, and adherence for people with serious mental illnesses will also prevent some violent episodes, even if it remains impossible to reliably predict which specific individuals would otherwise engage in the most serious acts of violence. (Psychiatric Services 62:1369–1371, 2011)