Fathali M. Moghaddam’s Staircase to Terrorism is included in the category of the “processual” radicalization models aiming at reconstructing the chronological and existential phases that transform an individual into a terrorist. As stated by Moghaddam, the more steps climbed by the individual, the fewer the chances that they can abandon the path toward terrorism. The perception that the individual has of the situation they are experiencing is fundamental.

According to Marc Sageman, radicalization is deeply rooted in group dynamics that are common to every human group. Faith and fanaticism are grounded and sustained in intense small group dynamics characterized by very tight ties.

Mitchell Silber and Arvin Bhatt published a four-phase radicalization model in 2007. According to the model, the jihadist ideology is the “primum movens” of radicalization. The model does not aim at explaining the radicalization process in general, but only a specific type of radicalization, that is the one that spontaneously takes place in Western cities.

The fourth milestone in the studies on radicalization is The Psychology of Terrorism, written by John Horgan, firstly published in 2005. Horgan notes that an individual can commit a violent act, but violence becomes more effective when an organization is able to mobilize a great amount of material and immaterial resources.

Radical Islam Rising, written by Quintan Wiktorowicz and published in 2005, aims at understanding how al-Muhajiroun – a radical Islamist movement that has also praised the 9/11 attack – rebuilds the identity of its new members.

McCauley and Moskalenko divide radicalization in three levels: individual radicalization, group radicalization, and mass radicalization.

The DRIA model was first published in Alessandro Orsini’s Anatomy of the Red Brigades (2009) and further developed in a series of articles and books devoted to the jihadi terrorists who succeeded in carrying out terror attacks in the West between 2004 and 2018. The DRIA model conceives of ideology as the necessary, albeit inadequate, condition for accepting the idea of killing and being killed. DRIA is an acronym that stands for: Disintegration of Social Identity Reconstruction of Social Identity through a Radical Ideology Integration in a Revolutionary Sect Alienation from the Surrounding World

The Three Pillars of Radicalization by Arie W. Kruglanski, Jocelyn J. Belanger e Rohan Gunaratna (2019) contains one of the most interesting and well-researched theories of radicalization, attaching equal importance to radical ideology as does the DRIA model. The three authors offer a psychological perspective on extremism as a general phenomenon of which radicalization leading to terrorism is just a particular case.

Social theorist Randall Collins helps us understand that to use violence in an effective manner, terrorists must control the flow of adrenaline that invades their bodies when they are ready to kill their victims. As is true for all people, terrorists also fear physical clashes; they fear killing and being killed. How do they control this fear and remain lucid when they shoot? Professor Orsini presents his article "Are Terrorists Courageous? Micro-Sociology of Extreme Left Terrorism" on how terrorists kill their vitims after having placed them in a desperate situation that does not allow for any escape.

In "The Al Qaeda Factor" Mitchell Silber examines sixteen Al Qaeda-associated plots and attacks, from the 1993 World Trade Center bombing to today. For each case, he probes primary sources and applies a series of questions to determine the precise involvement of Al Qaeda. What connects radicalized groups in the West to the core Al Qaeda organization in the borderlands of Afghanistan and Pakistan? Does one of the plotters have to attend an Al Qaeda training camp or meet with an Al Qaeda trainer, or can they simply be inspired by Al Qaeda ideology?

What is ethnography?

In "Sacrifice. My Life in a Fascist Militia" Professor Orsini tells how he joined two local groups of a neofascist organization he names "Sacrifice" in two neighboring cities with very different political cultures. Using participant observation, Orsini shows how fascists live day to day, how they understand their world, and how they build a parallel universe in which the correctness and probity of their attitudes are clear.