Diego Gambetta and Steffen Hertog, scholars at the European University Institute and the LSE respectively, have spotted a pattern: people with degrees in engineering are significantly over-­represented in jihadist circles, whether in the Muslim world or in the West.

One of the more attractive explanations they propose is something they term “relative deprivation” and has to do with the decline of Middle Eastern and North African economies in the 1970s and ’80s. In the Nasserist heyday of Arab nationalism, modern­ity was held up as the panacea that would deliver the Arab world from backwardness: an engineering graduate was all but guaranteed employment by the state. The financial stagnation of the 1970s forced a severe contraction of the state sector, leaving an underemployed surplus of highly educated, highly embittered young men. Many of them turned, not just against the state, but against modernity in its entirety.