How a study in the Stockholm subway could help prevent violent crime

Nearly half a million people are murdered around the world every year. While the means vary across nations – knives in Australia and the UK, guns in the US and Mexico – what is universal is the sense of hopelessness about these deaths. Yet there is a solution, one that comes from an unexpected source: the subway system of Stockholm, Sweden.

Since a solution can only be unexpected in relation to some conventional wisdom, it is useful to start by looking at how we have typically thought about the problem of interpersonal violence.

In most countries, right-of-centre political parties tend to think…