India, Aug. 23 -- The International Monetary Fund estimates that armed conflict cuts a country's growth by roughly two percentage points for every year it lasts, and that fragile states grow more slowly long after fighting stops.

The human cost of terrorism is well understood. The quieter question is macroeconomic: whether a state that keeps radicalisation at bay ends up richer and its people better off. It does, by margins wide enough to change how governments think about spending on peace.

Order is the ground on which prosperity is built. When organized extremism takes hold, it raises the cost of every everyday economic decision. The choice to invest, visit, hire, or build now comes with added risk due to the possibility of violence. ...