Marina Bolotnikova in Harvard Magazine:
Psychology professor Matthew Nock has spent his career studying self-harm, but he remains humbled by how little is yet understood about why people kill themselves. Suicide is the tenth highest cause of death in the United States, and the rate remained roughly steady across the population for the last century, before rising somewhat during the last few decades. Academic theories of suicide emerged in the nineteenth century. Émile Durkheim wrote about social determinants of suicide in his foundational (though now controversial) text on the differences in suicide rates among Protestants and Catholics in Europe. Freud thought depression and suicide reflected inwardly directed anger. As psychology became the domain of empirical research, clinicians came to rely on factors correlated with suicide—like depression, poor impulse control, or substance abuse—to determine whether a patient was at risk. But a recent review of several hundred studies of suicidal thoughts and behaviors during the last 50 years, co-authored by Nock and a team of fellow scholars in the Psychological Bulletin, finds that risk factors have been virtually no better than random guesses at predicting suicide.
…The predictive failure of individual risk factors may be linked with psychologist Thomas Joiner’s theory of suicide. He has argued that suicide risk depends not just on the will to die, but also on an additional “acquired capability” to kill oneself: the ability to overcome the fear of death through previous experiences of one’s own or another’s trauma, or intentional self-harm.