In the search for answers after the Paris terror attacks, French public intellectuals are responding to the question on everybody’s lips: Why did these people, our young people “made in France” (and Belgium) do it?

But as the battle of ideas rages between economists, sociologists, historians, anthropologists, psychiatrists and scholars of religion, the voice of Olivier Roy stands out among the crowd.

The world-renowned specialist of Islam and the geo-politics of the Middle East has developed a “third way” of understanding the new globalized jihadism. He believes the underlying cause is a deep generational fracture that has sparked an international jihadi movement from France to Tunisia, and Turkey to Saudi Arabia.

Young men in their 20s and 30s committing mass murder and suicide in the name of Allah, the political scientist argues, are extreme manifestations of a “generational nihilistic radicalized youth revolt” that is “more about the Islamization of radicalism than the radicalization of Islam.”

The Roy doctrine is shifting the debate beyond the familiar face-offs between the “blamers” pointing the finger at colonization, French and Western foreign policy, exclusion and racism, versus the “culturalists” convinced there is a clash of civilizations and religions between Europe and the Muslim world. In the former group, French economist Thomas Piketty sees inequality in the Middle East and Europe as the key driver of terrorism. In the latter, French philosopher Abdennour Bidar has diagnosed a “cancer” at the heart of Islam.

Roy’s argument has profound implications for how Europe should respond to its homegrown terrorist threat, especially as France rushes to shut down extremist mosques, arrest Salafist Imams, and launches “deradicalization” programs.

The author of Globalized Islam: The Search for a New Ummah is still keenly sensitive to the social context of the ISIL recruits and never discounts the influence of Islam and Salafism in “framing” the rage of the attackers.

“The issue is not that the Muslim population is turning jihadist,” Roy tells Quartz in an interview from his post at the European University Institute in Florence.

“The issue is that there is a big generational gap which is stronger in Muslim societies because these communities are experiencing a sudden change–cultural, sociological, political–in a very short timespan of 30 years.

“In France, the second generation (whose parents emigrated from the Maghreb countries like Algeria and Morocco in the 1970s or after) are in revolt against everything their parents represent.

“They reproach them for not have passed on ‘good’ Islam, for having become Westernized, for accepting their life as migrants slipping down the social ladder, and for not having revolted. They are living in a myth and are not political militants who want to create a new society.”

The fascination with jihad is therefore not a reaction to a difficult social, economic or cultural situation, even if the Paris attackers and their confreres were relatively isolated from their societies and Muslim communities.

If racism and social exclusion were the factors that pushed young people towards violent radicalism, there would be tens of thousands of jihadists instead of the hundreds who have left France for Syria today, Roy says.

Of course, it’s not just in France or Belgium that this youth movement is devastating families and societies.

“We cannot say that Saudi society is turning more fundamentalist or more jihadist,” Roy says, “but there hundreds of young guys from well-off families after having a good life [who] just go for jihad.”

Roy then points to Tunisia, the greatest numerical global exporter of jihadi fighters, and Turkey, where the fathers of young men who opt for terrorism call the police to tell them “beware my son is on the verge of doing stupid things.”

“We have declarations of the fathers of the Tunisians who killed tourists. We have the declarations of the Turkish father of the two brothers who killed a hundred people in Ankara. We have the declaration of [Paris attacks ringleader Abdelhamid] Abaaoud’s father.”

According to Roy, the West and Muslim communities worldwide are confronting a youth radicalization movement like that of the Baader Meinhof revolutionaries who wanted to take revenge on their parents’ generation of Nazi collaborators. He also compares ISIL terrorists to 19th-century French anarchists who vowed death to all the bourgeoisie. Today’s young radicals have “replaced the world proletariat with global Ummah (Muslim nation) and speak of infidels instead of the bourgeois,” he says.

“The young jihadists say ‘we are better than you.’ This is always what a youth movement says.”

Roy knows his contemporary subjects first-hand because he was a schoolteacher in the French suburbs in the late 1970s, working with the first-generation migrants and their children. He observed a lack of cultural and historical transmission of religious precepts and values and language difficulties, especially for the new arrivals from the Maghreb (from the former French colonies in North Africa).

The parents wanted their children to speak French, he says. But the parents “had a problem because their French was quite superficial and they could not pass on complex ideas. They passed on norms and said ‘don’t do that’ but without explanations. The norms were not connected with a system of values. Many of these parents were socially integrated in their country of origin. But in France they were at the bottom of the social ladder, so they were not respected.”

Now a small subset of second-generation kids are catapulting themselves from the conventional “youth culture” of nightclubs, social media, drinking, drugs, picking up girls and indulging in petty crime to deadly acts of terror.

“Radicalism is what attracts these young people, and annihilating ISIL won’t eliminate the terrorist threat–because the new jihadis are opportunistic and will find another banner under which to fight.”

“Many of the terrorists had no religious life at all. The Abdeslam brothers sold alcohol in their café! These guys joined ISIL because it is the strongest narrative on the market. And you are sure to make the headlines. They shout Allah Akbar but they kill in the same way as the Columbine killers in the US. They have the same motivations–frustration, narcissism, nihilism, fascination for death, and suicidal attitudes.”

“Radicalism is what attracts these young people, and annihilating ISIL won’t eliminate the terrorist threat–because the new jihadis are opportunistic and will find another banner under which to fight.”

If the terrorists come from a Muslim background, it is easier for outsiders to use an Islamic narrative to structure their transformation into violent radicals. But when we look at converts, Roy says, “the basic cocktail is the same”.

“They find in Islam the best way to express, experience and to live their rejection of society.

“Islam is not just a pretext. Salafism and jihadism frame their perception. But the sudden jump to revolt is why I speak of Islamization of radicalism.”

The contention that thirst for radicalism comes first, and Islamism second, is backed up by figures from France’s Interior Ministry.

Almost one in four “radicalization alerts” to France’s “Stop Jihadisme” hotline and government channels concern converts, with 62% from “Arab-Muslim families.” Of French fighters for ISIL in Syria and Iraq, almost a quarter are believed to be converts.

Roy’s case for a generationally-driven jihadism is especially illuminating when he describes the remarkable proliferation of bands of brothers amongst terrorist attackers of recent years in Europe and elsewhere.

The sibling phenomenon underscores the extent to which these children are revolting against their parents.

He cites the Tsarnaev siblings in the Boston Marathon bombings, the Kouachis (Charlie Hebdo), and the brothers involved in recent Ankara attacks in Turkey. The Paris attacks involved two sets of brothers: the Abaaoud brothers (Abdelhamid Abaaoud kidnapped his 13-year old brother and took him to Syria) and the Abdeslam siblings (Brahim, Saleh and possibly a third).

“It is interesting to see how they turn their spiritual brotherhood into a biological brotherhood,” Roy says. “They marry the sisters of their friends very often.”

Underpinning the radical shift is the fact that young terrorists usually feel betrayed and cheated by French and Belgian society and by the West–but not necessarily for socio-economic reasons.

So how can society handle a minority fringe of a young generation with a mass-murder wish before jihadists commit more atrocities on civilian populations?

Piketty and his supporters ignore the fact that among the Paris attackers and their predecessors, many had jobs, families, and secular lifestyles. What they didn’t have was the life or the sense of meaning they craved.

“Some of them turned their frustration into some sort of a narcissistic revenge of ‘I was a loser and I want to be a winner,'” Roy says.

“It is exactly what [terrorist Ahmedy] Coulibaly said in the Hyper Cacher,” the supermarket where he murdered four people after the Charlie Hebdo attacks in January. “He said ‘now you are afraid of me.’ He was taking revenge for humiliation and frustration.”

So how can society handle a minority fringe of a young generation with a mass-murder wish before jihadists commit more atrocities on civilian populations?

As France shuts down extremist Salafist mosques and Imams, imposes licenses for Muslim preachers and asks whether it can ban sermons in Arabic, Roy and other experts say the authorities are missing their mark.

Why? Because ISIL primarily recruits from a delinquent base of impious young men with a “loser complex” in search of a grand cause–typically non-practicing Muslims–as well as swelling ranks of women and converts.

Unlike the theologically-trained recruits selected by Al Qaeda, these sign-ups are rarely “Islamic” or devout to begin with. They speak the colloquial French of the suburbs, not Arabic, and don’t come to ISIL by reading the Koran or obsessively praying alongside their Muslim brothers.

“Deradicalization” campaigns are thus unlikely to dissuade them either, “because radicalism is exactly what the terrorists are looking for,” Roy says.

“It would be like proposing a course in economic liberalism to extreme-left revolutionaries. It is absurd and paternalistic.”