What is radicalization?

Uzair Ahmed and Milan Obaidi


  • Radicalization refers to the gradual social process into extremism and is often applied to explain changes in ideas or behavior.
  • A distinction exists between the cognitive and behavioral dimensions of radicalization, with the latter referring to engagement in extremist activities.
  • Radicalization as a concept is not absolute, but relative and dependent on the context in which it takes place.
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Key definition

The term radicalization received much attention following the 9/11 terrorist attacks. It is often applied to explain what happens before the bomb goes off.[1] Yet, the concept of radicalization is heavily contested and as a result, a universally accepted definition is yet to be developed since radicalization can have different connotations in different contexts, and it can mean different things to different people. Nonetheless, Van den Bos defines radicalization as a process of growing willingness to pursue and/or support radical changes in society (in an undemocratic manner, if necessary) that conflict with, or could pose a threat to, democratic legal order.[2] Further, Hafez & Mullins identify three elements that may be viewed as important for an comprehensive understanding of the concept: ‘Radicalization is usually a (1) gradual “process” that entails socialization into an (2) extremist belief system that sets the stage for (3) violence even if it does not make it inevitable’.[3]

History of the concept

Throughout history, the term has implied various meanings. It derives from the Latin radix (or root), understood as ‘relating to or affecting the fundamental nature of something’.[4] Its meaning changed from that of forces and processes that could change the basic attributes of an entity, to ‘thorough and sweeping political change’ by the 18th century. From the end of the 19th century, it referred to those who represented or supported sections of a political party that was viewed as extreme (remote or far from what is understood as the norm in a society).[5] However, since 2005, the term “radicalization” has been related to the adoption of extreme beliefs and violent behavior.[6]

Different conceptualizations

It is important to emphasize the distinction between cognitive and behavioral dimensions of radicalization. Cognitive radicalization refers to the process through which an individual increasingly endorses political ideas, beliefs, and values that are in opposition to fundamental values and norms of the society, including democracy and the rule of law.[7] The cognitive component of radicalization can be defined as ‘the social and psychological process of incrementally experienced commitment to extremist political or religious ideology’.[8] Behavioral radicalization, on the other hand, encompasses the behavioral outcome and refers to the process of participating in extreme activities, which could be either violent and illegal or non-violent and legal.[9] Thus, behavioral radicalization can be defined as a ‘collectively defined, individually felt moral obligation to participate in direct action’.[10] Consequently, radicalization can be seen as a social and psychological transformation whereby an individual increasingly adopts an extremist belief system, regardless if it ultimately results in actual violence or not. Although individual trajectories of radicalization vary from person to person, some suggest that it is possible to identify four stages of radicalization in which people: 1) Become susceptible to radicalization; 2) orient toward a particular type of radicalization; 3) become a member and get involved in radical groups; and 4) participate in extremist actions.[11]

Radicalization as such does not necessarily have to result in terrorism. Therefore, some scholars oppose the need for these attitudinal and behavioral aspects.[12] In fact, many terrorists do not go through a gradual social and psychological process as often described through the concept of radicalization.[13] Radicalization tends to be a nonlinear and dynamic process.[14] Furthermore, many terrorists are not ideologically motivated. Likewise, many who adopt radical beliefs do not precede with violent behavior.[15] Bjørgo & Horgan have therefore proposed a need for a clarification and concept divide, namely, describing radicalization as the gradual social process of adopting beliefs and values about the use of violence as a political means, and engagement as the process of changes in behavior.[16]

Finally, the meaning of the term ‘radicalization’ varies from context to context. This is particularly reflected in the various definitions of radicalization proposed by a large number of scholars and security agencies, which emphasize different aspects of radicalization, as illustrated above. It is therefore important to be concrete and not apply radicalization as an absolute concept.[17] Variation can be found amongst radicalized individuals and groups. The term is often applied in reference to individuals belonging to left-wing, Islamist jihadists, and right-wing groups and ideologies.[18] The latter includes historical examples of right-wing radicalization in Nazi Germany in the 1930s and the rise of the Ku Klux Klan in the US, as well as contemporary examples like the development of Alternative for Germany and the emergence of offline and online subcultural extreme right milieus. [19]


[1] Neumann, P.R. (2013). The trouble with radicalization. International Affairs, 89(4), 873-893.

[2] van den Bos, K. (2018). Why people radicalize. New York, USA: Oxford University Press, 565.

[3] Hafez, M., & Mullins, C. (2015). The radicalization puzzle: A theoretical synthesis of empirical approaches to homegrown extremism. Studies in Conflict and Terrorism, 38(11), 958-975.

[4] Mandel, D. R. (2009). Radicalization: What does it mean?. In T.M. Pic, A. Speckhard, & B. Jacuch (Eds.), Home-grown terrorism: Understanding and addressing the root causes of radicalisation among groups with an immigrant heritage in Europe (pp. 101-113). Amsterdam, Netherlands: IOS Press.

[5] Mandel (2009).

[6] Della Porta, D. (2018). Radicalization: A relational perspective. Annual Review of Political Science, 21, 461-474; Neumann (2013).

[7] Hafez & Mullins (2015); Vergani, M., Iqbal, M., Ilbahar, E., & Barton, G. (2018). The three Ps of radicalization: Push, pull and personal. A systemic scoping review of the scientific evidence about radicalization to violent extremism. Studies in Conflict and Terrorism, 1-32.

[8] Horgan, J. & Braddock, K. (2010). Rehabilitating the terrorists? Challenges in assessing the effectiveness of de-radicalization programs. Terrorism and Political Violence, 22(2), 267-291.

[9] Hafez & Mullins (2015); Vergani et. al. (2018).

[10] Githens-Mazer, J. (2009). Causal processes, radicalisation and bad policy: The importance of case studies of radical violent takfiri jihadism for establishing logical causality. APSA 2009 Toronto Meeting Paper. https://ssrn.com/abstract=1451634.

[11] van den Bos, K. (2020). Unfairness and radicalization. Annual Review of Psychology, 71, 563–88; Doosje, B., Moghaddam, F.M., Kruglanski, A.W., De Wolf, A., Mann, L., & Feddes, A.R. (2016). Terrorism, radicalization and de-radicalization. Current Opinion in Psychology, 11, 79–84.

[12] Bjørgo, T., & Horgan, J. (2009). Leaving terrorism behind: Individual and collective disengagement. New York, USA: Routledge; Borum, R. (2011). Radicalization into violent extremism I: A review of social science theories. Journal of Strategic Security, 4(4), 7-36.

[13] Moghaddam, F.M. (2005). The staircase to terrorism: A psychological exploration. American Psychologist, 60(2), 161–169.

[14] Feddes, A.R., Mann, L. & Doosje, B. (2013) Empirical study as part of a scientific approach to finding indicators of and responses to radicalisation (SAFIRE), Report presented to the European Commission. http://www.safire-projectresults.eu/.

[15] Bjørgo & Horgan (2009); Borum (2011).

[16] Bjørgo & Horgan (2009).

[17] Coolsaet, R. (2016). ‘All radicalization is local’. The genesis and drawbacks of an elusive concept. Egmont Paper 84, 3-48. Egmont Institute. http://www.egmontinstitute.be/content/uploads/2016/05/ep84.pdf?type=pdf. Sedgwick, M. (2010). The concept of radicalization as a source of confusion. Terrorism and Political Violence22(4), 479-494.

[18] Aust, S. (2009). Baader-Meinhof: The inside story of the RAF. New York, USA: Oxford University Press; Roy, O. (2017). Jihad and death: The global appeal of Islamic State. London, UK: Hurst Publishers; Klandermans, B., & Mayer, N. (2006). Context, alliances and conflict. In B. Klandermans & N. Mayer (Eds.) Extreme right activists in Europe: Through the magnifying glass (pp. 28–41). London, UK: Routledge; McVeigh, R. (2009). The rise of the Ku Klux Klan: Right-wing movements and national politics. Minneapolis, USA: University of Minnesota Press.

[19] Klandermans & Mayer (2006). Context, alliances and conflict. In Extreme Right Activists in Europe: Through the Magnifying Glass, ed. B Klandermans, N Mayer, pp. 28–41. London: Routledge; McVeigh (2009). The Rise of the Ku Klux Klan: Right-Wing Movements and National Politics. Minneapolis: Univ. Minn. Press; Hoffman, B. (1982). Right-wing terrorism in Europe. Santa Monica, USA: RAND; Rensmann (2018) Radical Right-Wing Populists in Parliament. German Politics and Society, 36(3): 41-73

By Uzair Ahmed and Milan Obaidi
Published Sep. 7, 2020 11:58 AM - Last modified Nov. 7, 2020 2:16 PM