Governments and independent experts have found countless metrics to evaluate the successes and failures of military interventions such as those in Kosovo, Afghanistan and Iraq, judging them on everything from casualty rates to the provision of public services. The number of girls attending school in Afghanistan, for example, has been a standard point of reference for supporters of the NATO mission there. But what metrics can be used to evaluate a deliberate nonintervention? This question is grimly relevant to assessments of the West’s decision not to take military action in Syria to date. Advocates of an intervention have a lot […]