Fighting terror needs evidence-based thinking

New York

AS policymakers and analysts wrestle with how to respond to the advancing Islamic State in Iraq and Levant (ISIL) extremists - also known as the Islamic State Iraq and Syria (ISIS) and the Islamic State - there is a danger of falling victim to a pervasive disease in international politics which might be called "recent-ism".

This is the hard-to-resist temptation to look no further back than the most recent crisis or analogy to develop policy. "Recent-ism" affects counter-terrorism, too; it's easy to make sweeping generalisations about how the threat is new and profoundly different.

Yet the actions of the group are neither. Resulting policy responses can be robust, but the campaig…