What is behind rampage killings?
Adam Lankford (in a NYT op-ed What Drives Suicidal Mass Killers) acutely identifies the key underlying motives of the perpetrators:
There appears to be a triad of factors that sets these killers apart. The first is that they are generally struggling with mental health problems that have produced their desire to die. … The second factor is a deep sense of victimization and belief that the killer’s life has been ruined by someone else, who has bullied, oppressed or persecuted him. …The third factor is the desire to acquire fame and glory through killing.
The desire for vengeance and the desire for fame are both deep-seated parts of human (especially male) nature. But why are they apparently motivating more men to become rampage killers of late?
Peter Turchin explains in Social Evolution Forum why more men may be feeling a desire for vengeance:
As the degree of cooperation in the American society declined over the last four decades, and the degree of intrasocietal competition rose, increasingly large numbers of susceptible individuals were victimized, bullied, and oppressed, and a certain (very small) fraction of them chose to become mass murderers to avenge such injustice.
The fundamental forces underlying this environmental change have been two structural-demographic trends – popular immiseration and elite overproduction. The first was correlated with the deterioration of working conditions, the second with the growing social pressures on the campus, which is why the two most common settings for shooting rampages are the workplace and the schoolyard. Overall, as the level of cooperation within the society decreased, social competition, political polarization, the dog-eat-dog economic climate, and the general level of nastiness increased.
Some might wonder if conditions are really getting so bad. Popular immiserization? Wages of unskilled workers have stagnated for decades. Median income too has stagnated. Signs of elite overproduction? People need bachelor’s degrees for jobs where once they needed high school graduates and graduate degrees where once bachelors degrees were enough.
Perhaps the desire for fame and glory is also affecting more men. Here I wonder if glorification of killers in movies and pop culture also plays a role.
The number of mentally ill is not increasing. But before the mental hospitals were emptied someone like Adam Lanza might have been locked up in an institution and left there.
So, overall we have an ultimate explanation (powerful innate motives of revenge and glory warped by mental illness) plus a proximate explanation (activated by particular current conditions).