It is intuitively appealing to connect the number of fighters a country sends to the Islamic State (IS) with poverty and inequality. The more desperate and economically downtrodden people are, the more likely it is that they'll join a terrorist group, right? Wrong, recent research indicates: It's much more likely that the reasons for the IS's recruitment success are cultural.
The terror militia has between 25,000 and 30,000 foreign fighters in Syria and Iraq. Disproportionate numbers of these radicals hail from Muslim nations: Tunisia alone is responsible for 6,000 of them, according to the Soufan Group.
Thomas Piketty, probably the most fashionable economist since the 2008 financial crisis, has linked the phenomenon to the high income inequality in Middle Eastern nations, which he argued the West had helped foster by letting oil sheiks get rich and share little of their wealth.
He also wrote that austerity policies applied in the wake of the crisis drove up unemployment levels and with them "national egoisms and identity tensions" that make immigrants feel unwelcome in countries such as France, which is the biggest western supplier of IS fighters.
Efraim Benmelech of Northwestern University's Kellogg School of Management and Esteban Klor from the Hebrew University in Jerusalem tested Mr Piketty's hypothesis in a recent paper and found it inconsistent with the data.
A Muslim woman in New York protests against the Islamic State. Muslims in many European countries are more likely to turn to radical groups than, say, in the United States or Canada. (AFP photo)
A 10% increase in a nation's per capita economic output is linked with a 1.5% point increase in the likelihood that its citizens will join the IS. Among non-Muslim countries, it is associated with a 5.1% increase in the number of recruits.
A higher Human Development Index is also positively correlated with the militia's success in a country. There are, however, no such correlations with inequality or unemployment. Otherwise countries such as Austria and Sweden wouldn't be among the top 20 countries by per capita IS recruitment.
Mr Benmelech and Mr Klor suggested a different explanation for recruitment success: It's positively correlated with homogeneity in a society. The less ethnically diverse a society is, the more likely outsiders such as immigrants or second- or third generation Muslims are likely to turn to terror. The economists wrote of the Western European nations that supply a relatively high number of fighters:
"The more homogeneous the host country is the greater difficulty immigrants such as Muslims from the Middle East experience in assimilating. As other research has shown, isolation induces some of them to become radicalised."
In other words, people don't join the IS because their countries are poor or in crisis or because bad economic conditions increase the pressure on outsider groups. They join when a wealthy society fails to integrate them so that they could share in the wealth. Resentment, a feeling of being left out appears to be a stronger motivation for the recruits than economic hardship.
One could argue that Mr Piketty's argument still stands: Native-born citizens might grow xenophobic for economic reasons regardless of their country's relative wealth -- it is perhaps more important how they perceive the change in their own living standards.
That's beside the point, however. Mr Benmelech and Mr Klor's findings support an empirical finding that often surfaces in reports on the foreign fighters. "In almost all cases," says a 2015 report from a task force formed by the US Congress' Homeland Security Committee, "suspects feel excluded from society or think they have failed to live up to expectations."
Mr Benmelech and Mr Klor's work could provide ammunition to those who argue Muslim immigrants don't really integrate into host societies. The economists show that in a non-Muslim country, the likelihood that its residents will join the IS increases with the size of the Muslim population.
Besides, every European country reports higher unemployment and lower incomes among Muslim immigrants than among the general population or most other immigrant groups, so it may well be that the inequality that breeds terrorism is not the kind measured by the Gini coefficient but the ethnically-driven one, which is harder to measure.
It's easy to say a certain group can't be integrated. Yet it's clear that some countries are more successful at making Muslims feel at home than others. The number of IS fighters relative to a country's Muslim population is indicative of that. Finland, Ireland, Belgium, Sweden and Austria have the biggest number of terrorist recruits among their Muslim communities. Denmark and Norway are not far behind.
These countries are economically and culturally advanced, as well as economically equitable, and they rank among the happiest in the world. Yet Muslims there are far more likely to turn to radical groups than, say, in the US or Canada.
Societies with a strong social fabric and a long history of homogeneity, like the Scandinavian ones, are hard for immigrants to break into. They often feel as though they're banging their heads against an invisible wall -- until they stop and, in some cases, pick up a gun.
Traditional countries of immigration have less radical Muslim populations. So do countries with Mediterranean cultures that are somewhat closer to the Middle Eastern one -- Italy and Spain.
The foreign fighter problem is one of the costs for traditionally homogeneous countries of trying to operate in a multi-coloured, unstable world in which the freedom of movement has dramatically expanded in the last 50 or 60 years.
This is not a problem that can be solved by security measures or a change in government policy: It may take decades for the prevailing cultures in these countries to become more receptive toward diversity.
It's a complex process that's not easy to monitor or describe with data, but it makes much more sense to study it in greater depth than to dismiss the radicalisation of Muslims as economically driven or inherent in their culture. ©2016 Bloomberg View
Leonid Bershidsky is a Bloomberg View columnist. He is a Berlin-based writer, author of three novels and two non-fiction books.