The attempted terrorist attacks in London and Glasgow three weeks ago surprised many people for two reasons: that the suspects were all educated medical professionals rather than desperate, uneducated vagrants; and that the job should have been botched so badly.
如今看来，受过教育的专业人士可能会从事恐怖活动，这一点不应太过令人吃惊。我的同事吉迪恩o拉赫曼(Gideon Rachman)曾提醒我们，奥萨马o本o拉登(Osama bin Laden)就是一个出自极端富裕家庭的工程师，他的副手也是一名医生。
That educated professionals might turn to terrorism should not, by now, be much of a surprise. My colleague Gideon Rachman has reminded us that Osama bin Laden is an engineer who comes from a fabulously wealthy family and his deputy is a doctor.
新书《恐怖分子从何而来？》(What Makes a Terrorist?)的作者、经济学家艾伦o克鲁格(Alan Krueger)对有关证据进行了系统性研究，希望对这种现象一探究竟。他的结论是：恐怖分子、政治极端分子和仇恨罪罪犯，通常都相对比较富裕。
The economist Alan Krueger, author of a new book called What Makes a Terrorist?, explores this phenomenon with a systematic study of the evidence. He concludes that terrorists, political extremists and those who commit hate crimes are often relatively well-to-do.
This is a difficult thing to prove, not least because each of those categories is controversial and there is a world of difference between, say, Northern Ireland and Sri Lanka. Krueger dips into different sources of data, each one imperfect, trying to build up a compelling picture from opinion polls, biographies of terrorists and broader studies.
Opinion polls from Gaza and the West Bank, conducted in December 2001, show that students and professionals are more likely than the unemployed or labourers to say that terrorism can be justified, and more likely to deny that a suicide bombing in a Tel Aviv night club should be described as "a terrorist act". (The polls reveal more unanimity than disagreement on these points, but certainly offer no evidence that education or wealth leads to more moderate views.)
When a graduate student at Princeton, the young economist Claude Berrebi gathered data on more than 40 Palestinian suicide bombers; he concluded that they were far better educated than the typical Palestinian, and also richer. Krueger offers a complementary picture using biographies of 129 Hizbollah fighters killed in action, although not necessarily while attempting a terrorist attack. They, too, were somewhat better educated and less likely to be poor than the typical young Lebanese man of the time.
More indirect evidence comes from studies of hate crimes, which are thought to have some parallels with terrorism. Again, economic motives are hard to find. It was once the conventional wisdom that lynchings in the American south were more common whenever cotton prices were low, indicating tough times for the economy. Historians no longer believe in the correlation. In general, hate crimes do not seem to be more common in economic downturns - although the economist Emily Oster seems to have found an exception in medieval witch-hunts, which were more common when crops failed.
All in all, the research that Krueger gathers together suggests that if there is a link between poverty, education and terrorism, it is the opposite of the one popularly assumed. We should not be surprised to find that terrorists can add up, read, and even write prescriptions.
What is more surprising is that the attackers in London and Glasgow were so incompetent. Claude Berrebi and the Harvard economist Efraim Benmelech studied - there's no nice way to put this - the human-resources policies of Palestinian terrorist groups. They found that older, better-educated terrorists secured more important suicide missions and killed more people. Having more than a high school education doubles the chance of escaping capture, for example.
If the terrorists in this case do turn out to be the doctors and other professionals who are, as I write, suspected of the crime, it would demonstrate that even years of education and experience do not guarantee a successful attack. Blowing up innocent people is obviously harder than it looks, and for that we can all be grateful.