Repression kick-starts a career in radical violence

When we choose our professions, a few become terrorists. Why? Many attribute this choice to ignorance or desperation. As Gordon Brown, then the Chancellor, said in 2004: "Poverty is a breeding ground for discontent. There is a sense of injustice. We have got to act if we are going to avoid the development of terrorist cells."

Alan Krueger is a distinguished labour economist at Princeton University. This book is based on the three Lionel Robbins lectures he gave last year at the London School of Economics on "What makes a terrorist", with a transcript of the discussion after each one; and it provides students, scholars and policy makers with a lucid and readable account of Krueger's findings.

The book contains a lot of statistical evidence on support for terrorism and participation in many countries, including opinion polls and large-scale datasets of terrorist incidents. Krueger finds no clear link to terrorist activity from either poverty or lack of education. Terrorists do not come disproportionately from countries with below-average income levels, nor do they have income or education levels that are below the average of the countries they come from. (An exception that Krueger notes is Northern Ireland, where participants in terrorist organisations were typically of below-average income and education.)

Another idea not supported by the data is that that the presence of US or coalition armed forces in the Middle East has stimulated terrorism. Robert Pape, a political scientist at the University of Chicago, argued this point recently in his influential book Dying to Win: The Strategic Logic of Suicide Terrorism (not listed in Krueger's otherwise inclusive bibliography). In contrast, Krueger finds that terrorists are no more likely to come from countries where Western troops are stationed than those where they are not.

He does find that terrorists aim their attacks at richer countries, particularly their interests and citizens abroad. It is not clear whether they do this because it is the richer countries whose foreign policies they object to or because, since richer countries tend to be democracies, they see their political systems as more open to influence through terrorist action or both.

What does make a terrorist? Krueger's big idea is that terrorists tend to come from backgrounds of restricted civil and political rights. In short, repression makes terrorists. This has major implications. One is that building a counter-terrorism policy around authoritarian governments in Pakistan and Saudi Arabia is likely to fail. Another is that we should not oppose terrorism by restricting our own civil and political liberties. Krueger suggests that the supply of willing terrorists is hard to influence, so we should focus on "degrading terrorist organisations' financial and technical capabilities, and... vigorously protecting and promoting peaceful means of protest, so there is less demand for pursuing grievances through terrorist tactics". Disappointingly, Krueger acknowledges but does not look closely at the possible reverse causation from terrorism to repression. Do increases in terrorist activity in a country, for example, tend to come before or after increases in repression levels?

His last lecture dealt with the effects of terrorism: how big are they? Krueger finds that the evidence can be read either way, but he concludes that isolated actions such as 9/11 do not have persistent economic or psychological costs in themselves: "Terrorism, as we have experienced it so far, only matters in a big way if we let it matter."

Why was this book written by a labour economist, not a political scientist? Krueger answers that he is professionally interested in understanding occupational choice - in this case, the career of a terrorist. But, as he also points out, opting to be a terrorist probably has more in common with voting choice than occupational choice in the conventional sense.

Another answer could be that, as a labour economist, Krueger has the skills to work with large datasets and evaluate the work of others who do the same. Many political scientists might lack these skills. In Britain, for example, Essex is the only research-intensive university to require students majoring in politics to learn quantitative methods. Few UK political science graduates will have much background in statistics and probability and consequently may have to leave such vital issues as "What makes a terrorist" to scholars from more numerate disciplines.

Mark Harrison is professor of economics, Warwick University, and distinguished visiting fellow, Hoover Institution on War, Revolution and Peace, Stanford University.