No one really dwells on the question of why so many young men from Europe, Canada, Australia, even China, are going to fight in Syria and Iraq with the so-called Islamic State (Isis), or with other Islamist militias. The New York Times recently published a map showing which countries the foreign volunteers come from. The numbers are slippery and often contradictory, but the foreign presence in Syria and Iraq is reckoned at around 17,000 fighters. The biggest contingents are from Chechnya and the North Caucasus (around 9000) and Turkey (1000). There are also 400 from Kosovo. But 1900 come from Western Europe (700 from France, 340 from Britain, 60 from Ireland), 100 from the US, and between 50 and 100 from Australia.