The Makings of a Terrorist: Continuity and Change Across Left-, Right- and Jihadist Extremists and Terrorists in Europe and North-America, 1960s-Present

ABSTRACT

This article conducts comparative research to advance our understanding of the causes of terrorism. Primarily, by assessing differences and similarities between left-, right- and jihadist extremists and terrorists, the prevalence of certain variables amongst populations of radicalized individuals will be determined. Secondly, by contrasting, where possible, these prevalence rates with representative samples from the broader population, the distinctiveness of these biographical details amongst extremists and terrorists is discussed. The article compares the Analysen zum Terrorismus, one of the most comprehensive studies of (left-wing) terrorism ever conducted, with original empirical work on contemporary right-wing and jihadist extremism and terrorism. Results suggest that extremists and terrorists from these contexts are not distinctive in terms of socio-economic backgrounds, educational achievements, criminal antecedents or suicide attempts. There does appear to be a higher prevalence of unemployment, broken homes and related childhood stressors. The importance of social movements and groups in drawing and anchoring individuals to extremism and terrorism is emphasized across ideological boundaries, as is the influence of societal and political contextual factors, such as political representation of extremist views.

Introduction

The atrocity of terrorist violence has drawn particular attention to the characteristics of those who perpetrate such acts (Horgan 2003). Determining the extent, strength, and consistency of the association between certain individual and environmental factors and perpetration, has been amongst the most practical ways by which terrorism researchers have sought to understand its causes. Much of this type of prevalence research emerged in the wake of the September 11^th attacks (Corner and Gill 2022). Prior to this, the most extensive and influential such study was a project initiated by the West-German authorities in 1977. As part of the Analysen zum Terrorismus, biographical data was compiled on 250 individuals suspected, or convicted of, involvement in terrorism. While conceptual and methodological issues require its results to be treated with care, the Analysen remain a unique source of information on the backgrounds of (mostly) left-wing terrorists, their group dynamics, as well the contribution of the broader social and political context to the emergence of terrorism. This article revisits the Analysen and compares its results with new, empirical data on 206 contemporary jihadist and right-wing extremists and terrorists. Through careful contextualization of the Analysen’s more robust findings, the present comparison advances discussions on the individual-level characteristics of extremists and terrorists, the role of group dynamics in drawing and anchoring them to extremist worldviews, as well as the importance of the broader political and social context in constraining and creating opportunities for political violence in Western countries by non-state actors.

Despite the quantity of academic output that has accompanied field-wide growth since 9/11 (Phillips 2021), progress on addressing key questions relating to terrorism, such as whether or not perpetrators are typified by particular predispositions or pathology, has been slow (Corner and Gill 2022). At least in part, this has stemmed from methodological difficulties in accessing data sources; individuals who have been involved in terrorism and can provide biographic, psychometric, or clinical data. Such work has also been hampered conceptually by a reluctance to disaggregate what it means for someone to be “radicalized,” often looking no further than those individuals who have conducted actual terrorist attacks, and foregoing the much larger number of extremists who will never use such violence (Schuurman 2020). A tendency to study the latest iteration of the terrorist threat has also infused the field with a focus on the immediate, one which fails to make full use of relevant insights from previous generations of scholars (Schuurman 2019). Finally, language barriers have hampered the integration of non-English texts into mainstream scholarly discourse, limiting the degree to which studies like the Analysen can inform contemporary debates.

Drawing the Analysen into a comparative assessment will not address all of these concerns. However, it will help alleviate the field’s contemporary-threat bias and redraw attention to an important, if flawed, study with which the post-9/11 generation of terrorism scholars has not engaged in detail. Most importantly, data drawn from the Analysen will broaden the empirical basis of our own in-depth study of the individual, group and structural-level determinants of radicalization outcomes amongst 206 Salafi-Jihadist and right-wing extremists and terrorists from Europe and North America. Considering the points upon which a comparison between the Analysen and our own work is possible, will allow us to identify commonalities and differences between extremist and terrorist individuals and movements separated by time and ideology, and offer a number of broad insights into the causes of these phenomena.

The Analysen zum Terrorismus and their reception

In the late 1960s in West-Germany, the dissolution of a broad, student-led protest movement set the stage for the rise of several, left-wing terrorist groups. These groups would dominate headlines for years to come, presenting the government with its biggest, post-World War II crisis. The state’s principal antagonist during the 1970s was the Baader-Meinhof group, also known as the Rote Armee Fraktion or Red Army Fraction (RAF), although others like the Bewegung 2. Juni (Movement 2^nd of June, B2J) and the Revolutionäre Zellen (Revolutionary Cells, RZ) broadened the left-wing terrorist threat. The “analyses on terrorism” were commissioned at a German conference of interior ministers in 1977, just after the apotheosis of the fight against the RAF known as the “German autumn.” This dramatic sequence of events began with the kidnapping of industrialist Hanns-Martin Schleyer by a RAF cell. It was followed by the hijacking of a Lufthansa flight by operatives of the Palestinian Front for the Liberation of Palestine (PFLP). They intended to put further pressure on the West-German government to concede to the kidnappers’ demands. After the passengers and crew were rescued by the newly-formed GSG9 counter-terrorist unit, three RAF leaders imprisoned in Stammheim (whose liberation had been the central focus of the kidnapping and hijacking) died by suicide. The operation a failure, Schleyer’s kidnappers murdered their captive and left his body in the trunk of a car in northern France (Aust 2017).

The purpose of the Analysen was to uncover the causes of the left-wing violence and terrorism that had gripped West-Germany. The project’s results were published in four volumes (the last of which in two parts) that were released throughout the 1980s. It was the biggest project of its kind in the German language, and remains among the most comprehensive assessments of the causes of terrorism in any language today (Kraushaar 2004). Nonetheless, its influence has, on the whole, been limited. In the polarized atmosphere of the late 1970s, the project’s announcement led to immediate distrust; how could academic independence be maintained when the funders had a direct stake in the matter (Kreissl 1983)? As the research team was selected in part to specifically reflect both “right-” and “left-wing” views, the project faced allegations of bias, contradictory results and insufficient professional ability (Blankenburg 1985; Scheerer 1993). Rather than operationalizing “terrorism” as a nonpartisan, observable phenomenon, the team adopted a governmental definition which lacked neutrality. Critics also found the project one-sided in its focus on terrorist groups like the RAF, accusing it of underemphasizing the role of state institutions, as well as the interplay between the forces of revolution and reaction, in contributing to the emergence of militancy (Blankenburg 1985; Narr 1989).

The second volume of the project relied on biographical data from 223 left- and 27 right-wing extremists and terrorists, as well as primary data gathered through interview-based, psychoanalytical assessments. This volume has attracted the brunt of the criticism. Methodologically, the study bore a number of shortcomings in relation to data and sampling, some of which were recognized by the authors themselves (Jäger 1981; Süllwold 1981). The sample included suspected as well as convicted terrorists and drew very low response rates on several variables. As the data were collected indirectly through government employees, there was an overall lack of transparency regarding the precise data sources. Furthermore, in terms of sources of confounding, there was a reliance on subjective impressions to determine exposure across the sample, rather than incorporating validated measurements for items like intelligence or social aptitude (Gipser et al. 1984; Kreissl 1983). Finally, the biographical information was not analyzed beyond descriptive, summary statistics, nor was it consistently compared with relevant segments of the broader population, leaving it unclear if (and to what extent) the information provided was specific to the study sample (Blankenburg 1985; Gipser et al. 1984). This volume was also singled out as an attempt to reduce the complex causes of terrorism to psychological or psychoanalytical issues and underrepresenting the role of broader society and the state (Gipser et al. 1984). Moreover, the psychoanalytical conclusions were seen as impressionistic and drawn only from a handful of interviews conducted without a guarantee of confidentiality (Kreissl 1983; Narr 1989).

Whilst the methodological criticism of the Analysen should be acknowledged, it is worth noting that the overall critique of the project, as well as its scathing tone, seems excessive at times. The Analysen’s authors seemed well-aware of the methodological limitations underpinning their work (Böllinger 1981; Jäger 1981; Neidhardt 1982b; Süllwold 1981) and even went some way toward addressing them in the project’s final, and more warmly received, volume (Kreissl 1983, 1985; Narr 1989). Furthermore, whilst the methodology employed to determine the pervasiveness of personality traits, for example, was ill-fitted, the data gathered on demographic and other, categorical variables should not be interpreted with the same level of scrutiny.¹ Indeed, it may be the case that these critiques were rooted in long-standing, divisive debates about the causes of terrorism in West-Germany (Merkl 1995) and should, therefore, not completely dissuade a new generation of terrorism scholars from considering and contextualizing some of the Analysen’s main findings (e.g., Koehler 2021; Logvinov 2021). The Analysen’s individual-level data can continue to contribute to scholarly debate on understanding involvement in extremism and terrorism, but only when the most robust findings are interpreted cautiously, with full acknowledgment of their methodological constraints, and contextualized carefully with new samples of radicalized individuals.

Research design

The foundation for this article is the “(Non-) Involvement in Terrorist Violence” (NITV) dataset. Originally intended to study differences in radicalization-process outcomes between extremists who use terrorist violence and those who do not, the NITV dataset can also be configured for other purposes. In this article, the NITV dataset (N = 206) is used as a source of information on right-wing (n = 103) and Salafi-Jihadist (n = 103) extremists and terrorists from Europe and North America, enabling a comparison with similar information on the (largely) left-wing extremists and terrorists found in the Analysen. The NITV sample is 90% male, and 70% of the sample were members of particular right-wing extremist or Salaf-Jihadist groups, with the remainder classified as “lone actors” (i.e., affiliated with these broader movements but not involved in a particular cell or group). The mean year of birth is 1980 (SD = 12.47).

Definitions

The NITV dataset focuses on individuals who “radicalized to extremism,” which means that they adopted worldviews explicitly in favor of revolutionary change and (or) viewed the use terrorism as legitimate and necessary means. Terrorism here is the premeditated (threatened) use of deadly violence against civilians and noncombatants intended to generate attention for the perpetrators’ cause or ideology, in turn coercing opponents and inspiring adherents (Schmid 2013). Distinguishing between extremism as a cognitive frame and terrorism as a form of violent behavior is crucial, as most people who radicalize to extremism will never actually engage in such violence (Horgan, Shortland, and Abbasciano 2018). We purposefully use “extremists and terrorists” when discussing data from the Analysen and our own work, to emphasize that we are dealing with individuals who occupied a spectrum of roles in extremist groups and movements, and that only some were personally involved in terrorist attacks.

Case selection

Case selection was focused on European and North-American countries, with the United States, Germany, the Netherlands, and the United Kingdom being the most strongly represented (Table 1). Where comparisons with the broader population are feasible, it is on data about these countries that we rely most often. To ensure broadly comparable social and political backgrounds, the NITV sample only includes so-called “homegrown” extremists and terrorists (Crone and Harrow 2011), being individuals with strong ties to the countries in which they radicalized (e.g., through citizenship or being raised there). This means that we excluded individuals, like the 9/11 attackers, who traveled to these countries solely for the purpose of committing an attack. Neither did we include “foreign fighters” who traveled from these Western states to foreign conflict zones, as the often-limited information on their activities there usually prohibited accurate data collection. Moreover, foreign fighting on behalf of groups such as “Islamic State” is arguably better classified as insurgency rather than (solely) terrorism (Duyvesteyn and Fumerton 2009), meaning that their inclusion in our dataset would risk blurring the boundaries of the phenomenon being investigated.

Table 1. NITV geographical coverage.

Country	Frequency	%
United States	79	38.3
Germany	35	17.0
The Netherlands	25	12.1
United Kingdom	25	12.1
Sweden	11	5.3
France	9	4.4
Canada	8	3.9
Belgium	4	1.9
Norway	4	1.9
Austria	2	1.0
Denmark	2	1.0
Australia	1	0.5
Switzerland	1	0.5
Total	206	100.0

Data collection

An extensive literature review on the causes of (non-) involvement in terrorism formed the basis for a 159-variable codebook, which enabled systematic data collection. Following established practice in research on the causes of terrorism (e.g., LaFree and Ackerman 2009), variables at the structural, group and movement, and individual levels of analysis were considered. Structural-level variables describe the broader social and political context against which extremism and terrorism emerges, and consider, for instance, whether extremist political parties exist that offer electoral alternatives to the use of terrorism. Group- and movement-level items assess if and how extremist social movements, or specific groups within them, influenced individuals’ radicalization processes. For instance, through the availability of extremist role-models that invite emulation, or the presence of small-group dynamics that engender ideological and behavioral conformity. At the individual level of analysis, our codebook draws attention to the biographical characteristics and backgrounds that have been hypothesized as relevant for understanding radicalization processes. These include details on individuals’ upbringing, their educational and vocational achievements, and pathways into extremism.

Data collection took place between January 2020 and December 2021 and was conducted solely by the authors. A variety of sources were used, and triangulated whenever possible in order to minimize biases and inaccuracies. In addition to secondary sources such as newspaper articles, academic literature, and court verdicts, we sought out primary data where feasible. This resulted in 37 interviews with (former) extremists and terrorists, as well as primary data drawn from 56 autobiographies and 19 files provided to the first author by the Dutch Public Prosecution Service. All interviewees were provided with a description of the research project and asked to sign a consent form if they wished to participate. All data were anonymized upon input by removing details such as name, precise date of birth, place of residence and details about potential criminal offending. Ethics approval for the research project was granted by Leiden University’s Faculty of Governance and Global Affairs Ethics Committee in November 2019.²

To assess the reliability of the coding (as well as to account for any bias on behalf of the authors), the coded data underwent a two-stage process of inter-rater reliability (IRR) testing. Over an eight-month period, a case was randomly identified and independently coded by the authors. Both authors compared their coding on each variable and a percentage agreement was calculated.³ Any sources of disagreement were discussed and, where necessary, re-visited on other coded cases. Second, to account for coders guessing the same answer, Cohen’s kappa (κ) was calculated on the percentage agreement on each, compared case. On average, the IRR-score indicated “substantial” levels of agreement between coders across the eight-month period (M = .65, SD = 0.06), as defined by Landis and Koch (1977). At no point did the kappa score indicate less than “moderate” agreement between coders.

Comparing the NITV and Analysen datasets

The 250 anonymized cases on which the Analysen draws, were individuals convicted or suspected of terrorism-related offenses; 227 were left-wing extremists (mostly RAF, some B2J and RZ) and 23 were right-wing extremists (Schmidtchen 1981). Though flawed, the biographical information on the 250 extremists and terrorists contained in the Analysen provides the field with valuable individual-level, empirical data. In the comparative analysis below, we discuss those data points that have not drawn particular criticism and for which a comparison with our own dataset is at least broadly possible. This means that we will not be considering the Analysen’s psychoanalytical parts but focus instead on the more straightforwardly descriptive biographical details.

The comparison between the NITV dataset and the information contained in the Analysen is distinctly exploratory for several reasons. First of all, there is no underlying Analysen dataset available that we could manipulate or clean to more closely match our own data or coding procedures. All references to Analysen data in this article describe the results of that study as presented by the respective authors in running text, or as tables with descriptive statistics. Secondly, whereas our data covers a range of countries (Table 1), the Analysen’s results are limited to West-Germany. Third, both studies relate to different time frames, with the Analysen describing the 1960s and 1970s and our own work covering the 1980s to 2010s.

While acknowledging the different social and political contexts that have influenced the extremists and terrorists described by both datasets, we argue that the mechanisms underlying radicalization processes remain fundamentally comparable. For instance, a desire for revolutionary change, and the appeal of membership in a close-knit group which shares a sense of fighting for a greater good, are as relevant to understanding radicalization processes among contemporary jihadists and right-wing extremists, as they were to left-wing extremists in West-Germany of the 1970s (McCauley and Segal 2009). Similarly, the escalatory tendencies stemming from the development of an increasingly antagonistic relationship between radicalized social movements and the state are not unique to the development of groups like the RAF or B2J, but a mechanism that has influenced a range of rebels and extremist groups (Duyvesteyn 2021). Moreover, the very existence of differences between the groups and individuals being compared allows for the identification, or lack thereof, of similarities across cultural and historical contexts.

Statistical procedure

In so far as possible, we incorporate comparable, statistical procedures to those employed by the Analysen’s authors, including their procedures on missing data. First, the basic features of the points of comparison are compared descriptively and presented as percentage differences. In line with the Analysen, unless otherwise stated, valid and invalid cases are included in these prevalence rates. For certain variables in the Analysen, however, the authors report prevalence rates on valid cases only (i.e., listwise deletion). For accurate comparison, we then do the same but consider whether data is missing “at random” (see Perkins et al. 2018: 569), and report cautiously if this is not the case. Next, to go beyond descriptive, summary statistics and determine the strength of certain differences or associations in the NITV dataset alone, additional, inferential statistics are introduced. As the majority of data are categorical, Pearson’s chi-squared tests are used to determine if a statistically significant difference exists between the observed and expected frequencies in the relevant categories. The strength of the association(s) is quantified using an odds ratio.⁴ Certain variables in the NITV dataset provide opportunities for mean-difference testing and this is done using t-tests, with Cohen’s D for the effect size.

An explorative comparison

In the following sections, the main points of comparison across the Analysen and NITV datasets will be discussed and, where possible, contextualized with broader, non-radicalized populations. Given the different approaches to data collection and coding procedures, this comparison remains exploratory in nature.

Socioeconomic background, education & employment

The West-German left-wing extremists studied in the Analysen largely came from (upper) middle-class backgrounds, defined by the employment and educational achievements of their fathers. The small sample of right-wing extremists, on the other hand, tended to stem from working-class families (Schmidtchen 1981), suggesting that socio-economic disparities may exist between extremist milieus. We gauged the socioeconomic status (SES) of the NITV sample by looking at a number of indicators: both parents’ educational achievements, whether either or both were consistently employed, the perceived societal status of that employment,⁵ and whether a joint income estimate positioned them as low, average or high, as compared to modal incomes in their respective countries. What resulted was a 10-point scale in which right-wing extremists averaged 4.4 and jihadists 3.9. Although the jihadist sub-group had more missing values on this item, the finding nonetheless indicates that the aggregate NITV sample belonged, broadly, to middle or lower-middle class backgrounds. In other words, in line with the Analysen’s main finding (but in contrast with its note on West-German right-wing extremists), there is little to suggest that growing up in (relative) poverty is over-represented among individuals who will later radicalize to extremism in Western countries (Table 2).

Table 2. Summary of biographical comparisons^a.

Variables Dataset(s)

Analysen

Various

NITV

General population

LWEX (n = 223)

RWEX (n = 27)

General population

RWEX (n = 103)

Jihadist (n = 103)

Socioeconomic Background, Education & Employment

Family SES

–

(Upper) middle class

Working class

–

Middle class

Lower middle-class

Upper-secondary school education

19%

47%

9%

–

56%

66%

Unemployment

1%

10%

–

4% − 21%

19%

22%

Abandoned employment

–

–

–

–

18%

34%

Abandoned education

12%

65%

–

31%

53%

Conflict, Crime, Loss, and other Biographical Stressors

Conflicts with parents

–

33%

–

–

–

Broken home before age 14^b

“Lower”

25%

–

–

–

–

Poor family cohesion

–

–

–

–

58%

61%

Criminal antecedents

–

33%

19% − 60%

–

–

Violent crime

–

–

–

18%

25%

Nonviolent crime

–

–

–

27%

38%

Loss of one or both parents^b

–

26%

1% − 4%

12%

7%

Parental divorce/separation^b

1936-1945

13%

9%

–

1965-2019

20%-30%

1980–2020

52%

48%

1946-1955

3%

5% - 17%

–

1956-1965

2%

17%

–

Mental Health Issues

Suicide attempt(s)^b

6%^c

6%

–

2% − 6.5%

4%

2%

^aThe comparisons in this table need to be contextualized. Please refer to the main text for applicable interpretations.

^bPercentage of valid cases.

^cPrevalence rate for extremists is described as “proportionate” to the broader population (Süllwold 1981: 101).

The Analysen report that 47% of the left-wing extremists and terrorists had either gone to university or, somewhat ambiguously, received the type of high-school qualification that would enable direct access to university. The argument posited in the Analysen was that their left-wing sample were much more likely (than young people of a similar age) to have gone (or had the opportunity) to go to university (47% versus 19% respectively); at 9%, the right-wing extremists in the Analysen were below average in this regard (Schmidtchen 1981). To match the Analysen’s interpretation of high-school education that allows access to university, we coded our sample for completion of “upper-secondary” education (also known as the ISCED-3 level), which, in many countries, is a stepping-stone to university (See “Appendix A” in Miller, Warren, and Owen 2011). In the NITV dataset, 56% of right-wing extremists and 66% of jihadists had completed upper-secondary education or gone to university either before or during their radicalization (Table 2).

These figures suggest that extremists’ pursuit of upper-secondary and tertiary education is not exclusive to left-wing ideologies. Further interpretation is unfeasible, however. The Analysen do not disaggregate their data on educational attainment in a way that provides clarity on the percentage of extremists and terrorist that actually went to university, as opposed to those who had the opportunity to do so. As we did not track the educational progress of our sample after their radicalized periods, we cannot provide comparisons with the educational achievements of broader populations, which is usually given in terms of life-time prevalence. While the disparity in educational achievements between left- and right-wing extremists and terrorists noted in the Analysen seems particular to the West-German context of the 1960s and 1970s, broader questions about the relationship between education and radicalization remain unaddressed.

Looking at employment, the Analysen note that 10% of those who would go on to join underground left-wing groups were without work, as opposed to only 1% of the broader West-German youth cohort (Schmidtchen 1981). Within our sample, 19% of right-wing extremists and 22% of jihadists were unemployed.⁶ Given that the individuals in our sample had an average age of birth of 1980, the overview of 1991–2019 unemployment rates among people aged 15–24 collated by The World Bank (2021) provides a useful source of comparative data. During this period, youth unemployment was between 8% and 18% in the United States, between 4% and 13% in the Netherlands, between 6% and 16% in Germany and between 10% and 21% in the United Kingdom. Although the contrast is less stark than that reported in the Analysen, this comparison with World Bank data does suggest that radicalized individuals face higher unemployment rates than the broader population (Table 2).

Participation in pro-social institutions like education or work has long been hypothesized to lower the chance of involvement in delinquent behavior (Hirschi 1969). Recent empirical studies lend support to the applicability of such protective factors in the context of extremism and terrorism as well (Becker 2021). The comparatively high unemployment rates in both the Analysen and NITV datasets thus suggest that radicalized individuals may be characterized by fewer work-related ties to society. This is underlined by our finding that 18% of right-wing extremists and 34% of jihadists who were employed during their involvement in extremism or terrorism, left or lost their jobs. We also noted that 31% of right-wing extremists and 53% of jihadists enrolled in any form of education abandoned it without a degree (Table 2). Here, abandonment was more strongly associated with the jihadist sub-group whereas continuing to pursue education was more strongly associated with the right-wing extremist sub-group, X² (1, N = 128) = 5.60, p = .02 (OR = 2.37).⁷ Although the Analysen provides no information on job retainment among their sample, it does report that 65% of the combined sample who attended university left without a degree, compared to 12% of the broader student population (Schmidtchen 1981). A loosening of ties to prosocial institutions, such as work and education, appears to be a general characteristic of radicalization trajectories, with the latter being particularly salient among those aligned with jihadism.

Conflict, crime, loss and other biographical stressors

Criminological research suggests that childhood exposure to stressors increases the likelihood of future delinquent behavior. Commonly cited stressors are intra-family matters such as the absence of active and supportive parental involvement, lack of emotional warmth, the dissolution of the family through divorce or separation, or the death of a parent (Farrington, Loeber, and Ttofi 2012). Juvenile delinquency has, in turn, been linked to a greater likelihood of criminal behavior, including terrorism, in adulthood (Desmarais et al. 2017; Motz et al. 2020). The Analysen report a high percentage of its sample experiencing such biographical stressors; 33% had conflicts with their parents, 33% committed crimes prior to radicalization and 26% lost their father, mother, or both. Furthermore, 25% of the left-wing extremists and terrorists in the sample were reported as growing up in broken homes before age fourteen. This was noted as being above average. These stressors are hypothesized to reflect a generational conflict, especially between fathers and their children (Schmidtchen 1981).

While a direct comparison on the rate of broken homes and conflicts with parents is not possible, it is interesting to note similarly high figures for broadly comparable items in the NITV dataset. We coded 58% of right-wing extremists and 61% of jihadists as growing up in a familial environment characterized by fractured relationships, lack of emotional warmth and (or) frequent conflict. Looking at the percentage of individuals who lost either or both parents before age 21, this was the case for 12% of right-wing extremists and 7% of jihadists. On criminal antecedents, we noted that 27% of right-wing extremists and 38% of jihadists had a history of nonviolent criminal behavior, such as stealing or vandalism. For violent criminal antecedents, these figures are 18% and 25% respectively (Table 2). Taken together, these findings suggest that childhood exposure to a variety of stressors, as well as involvement in juvenile delinquency, is common across individuals who radicalize to extremism later in life, irrespective of the particular ideological character of that extremism. What remains unclear is the extent to which these individuals stand out from the broader population.

A 2020 study estimated that 3% of children under the age of 18 in the United States had experienced the loss of a parent (Burns et al. 2020). Data from 2004 indicates that 4% of children between five and 16 in the United Kingdom had lost a parent or sibling (Fauth, Thompson, and Penny 2009). The Dutch national statistics agency estimated that, in late 2011, only 1% of children aged 18 years or younger had lost one or both parents (Centraal Bureau voor de Statistiek 2013). When these figures are compared with the data points discussed in the previous paragraph, it becomes clear that the loss of one or both parents may be more prevalent amongst individuals who will later radicalize to extremism.⁸

When collecting information on criminal behavior prior to radicalization, we included self-reported delinquency described in (auto)biographies or interviews as well as official data on arrest or imprisonment. Therefore, the International Self-Report Delinquency Studies (ISRD) project provides a relevant source of comparative data, though caution remains necessary as the disparate studies do not overlap exactly in terms of time period, their subjects’ age-range, definitions of (violent) crime and how the data were gathered. Nonetheless, set against 40% and higher self-reported total youth⁹ delinquency in the United States, Germany and the Netherlands, and Barberet’s (2004) report that 35% − 60% of young people in the UK and the Netherlands have committed property offenses and 19% − 34% have committed violent offenses, neither the Analysen’s finding that 33% of their sample had committed criminal acts prior to radicalization, nor the NITV’s rates of violent and nonviolent antecedents, given above, stand out. At first glance, therefore, the criminal antecedents of extremists and terrorists do not appear to be remarkable, though it remains possible that differences exist in terms of the seriousness of the offenses committed.

We found no benchmarks for the prevalence of intra-family strife among broader populations that allowed a direct comparison with Analysen or NITV data. Instead, we turn to divorce rates as a proxy measure, though we acknowledge their limited utility as parental divorce or separation does not necessarily reflect limited emotional warmth or pedagogical involvement of parents vis-à-vis their children. Using historical data on West-Germany, Wagner, Schmid, and Weiss (2015) found that 13% of first-time marriages concluded between 1936 and 1945 ended in divorce within 10 years. This figure dropped to 3% for the 1946–1955 marriage cohort and 2% for the 1956–1965 one. The Analysen provide year-of-birth cohorts for the left-wing extremists and terrorists that allow a broad comparison here (Schmidtchen 1981). Among the left-wing extremists and terrorists born in or before 1945, 9% experienced parental divorce. Comparison with the 1936–1945 marriage cohort, from which many were likely born, suggests divorce rates in line with expectations. Yet, those born between 1946 and 1950 experienced 5% divorce rates, going up to 17% for those born from 1951 onwards. This suggest that the relatively younger cohorts of West-German left-wing extremists and terrorists experienced parental divorce more often than the broader population.

Within our sample, with an average year of birth of 1980, 52% of right-wing extremists and 48% of jihadists had experienced parental divorce or separation during childhood (Table 2).¹⁰ A 2016 survey of children’s health in the United States found that 22% of children under the age of 17 experienced the divorce or separation of a parent or guardian (Crouch et al. 2019). A 2004 report by the German government noted substantially increased divorce rates since the mid-1960s and estimated that 20% of children born specifically to married couples in 1990 would experience parental divorce before their 20^th birthday (Engstler and Menning 2004). In the Netherlands in 2019, around 30% of 17-year-olds had separated parents (Centraal Bureau voor de Statistiek 2021). Finally, Bellis et al. (2014) found that 24% of 18–70 year-olds in the United Kingdom had experienced parental divorce or separation, although their study focused on a relatively deprived subsection of the population rather than a nationally representative sample. Irrespective of ideological affiliation and time period, parental divorce or separation appears notably more frequent among future extremist and terrorists than it does among broadly comparable, non-extremist populations of a similar age.

Mental health issues

Given both the influence and controversy that have emerged from the Analysen’s psychoanalytical sections (Corner and Gill 2022), the dearth of actual empirical data that the study provides on its sample’s mental health characteristics is surprising. Nevertheless, the study does report that 6% of the left-wing extremist subsample had attempted suicide in the time period before radicalization. Although no further information is provided, this rate is described as proportionate to the broader population, based on the argument that 5% of the general population will, at some point in their lives, access psychiatric or psychotherapeutic help (Süllwold 1981).

Finding comparative data on suicide attempts is challenging as these rates fluctuate over time and differ between countries and across societal groups (Shain 2007; Weissman et al. 1999). Adolescence appears a particularly vulnerable time, with a 2009 study finding that 6.5% of 14–17 year-olds in Germany and the United States had a history of suicide attempt(s) (Plener et al. 2009). A summary of similar prevalence studies between 1986 and 1995 shows that 10% of U.S. high school students (median age 14–18) engaged in one or more suicide attempts. Outside of the U.S., some 7% of 13–19 year-olds reported similar behavior (Safer 1997). Suicide attempt prevalence appears to decrease notably for the post-secondary school age cohort. In the 2001–2003 period, 1.8% of Europeans between 18 and 24 years old had ever attempted suicide, with the overall lifetime prevalence for Germany specifically being 1.7% (Bernal et al. 2007). College students, however, may represent a higher-risk group with a study finding 3.2% of U.S. college students reporting a lifetime suicide attempt (Mortier et al. 2018).

The Analysen does not break down the reported suicide attempts by age cohort and we could not find data on suicide attempts specifically among young people in West Germany in the 1950s and 1960s. However, there is a strong relationship between suicidal ideation, suicide attempts and actual suicide rates (Klonsky, May, and Saffer 2016). Knowing that suicide rates in (West) Germany dropped considerably from the late 1980s onward, compared to the post-WW2 decades, therefore suggests that suicide attempts followed a similar trajectory (Müller 2007). In other words, youth suicide attempt rates during the 1950s and 1960s are likely to have been above contemporary rates. The 6% reported in the Analysen seems in line with figures for adolescent and student-population suicide attempt rates currently and is therefore unlikely to have been exceptionally high at the time.

In our dataset, the mean age at onset of radicalization was 19.7 (SD = 7.80) for right-wing extremists and 21.0 (SD = 5.50) for Salafi-Jihadists. Amongst the former, 4% were coded as having attempted suicide prior to radicalization, whereas this figure stood at 2% for the jihadists (Table 2). Whilst we lacked the detail necessary to place these attempts in a particular age cohort, the figures seem to fall well within the ranges of youth and adolescent suicide attempts discussed above. As far as this particular manifestation of mental health issues is concerned, its prevalence in the life histories of left-, right- or jihadist extremists does not seem to exceed that of young adults in the broader population.

Group dynamics

As the authors of the Analysen point out, radicalization to extremism and involvement in terrorism cannot be explained solely through the individual level of analysis (Schmidtchen 1981; Süllwold 1981). For a majority of cases, small-group dynamics or interactions with broader social movements exerted an important, oftentimes crucial, influence. The benefits offered by extremist groups and movements, such as acceptance into a tight-knit community of likeminded individuals, can be key to offsetting the very real risks of imprisonment or death. Peer pressures toward ideological conformity, a desire for in-group significance, or the emulation of violent role models, are some of the mechanisms by which group processes can affect members’ worldviews and behavior (McCauley and Moskalenko 2008). The groups from which terrorist attacks emerge (and the broader social movements to which these entities relate) should, therefore, be included in any attempt to explain the behavior of individual extremists or terrorists. The Analysen offer numerous insights at this level of analysis for which broad comparisons with our own findings are possible.

West German left-wing terrorism has been described as a “waste and decay product” brought about by the dissolution of the much broader student-led protest movement at the end of the 1960s (Sack 1984: 107). While the RAF’s violence came to dismay many left-wing radicals, its worldview was still rooted in a shared sense of anti-imperialist, anti-capitalist and countercultural sentiments. Prior to involvement in terrorist groups, 32% of left-wing extremists had participated in illegal demonstrations, and at least 25% had attended legal ones (Schmidtchen 1981). Of the students who would become involved in groups like the RAF and B2J, 57% had participated in new forms of collective living such as communes, which is hypothesized to have played an important role in their socialization to countercultural political and societal norms (Süllwold 1981).

The perceived attractions of left-wing extremist group membership, such as a sense of belonging or personal significance, were an important mobilizing force, especially among individuals who came from broken homes (Süllwold 1981). Yet recruits did not always actively seek out organizations like the RAF and B2J; in many instances, chance played a key role in bringing young people into the ambit of terrorism (Claessens and De Ahna 1982). One of the group-level mechanisms that appears to have subsequently tied individuals to extremist groups, is the influence of ideologically extremist persons of influence. The presence of such role models was noted by 39% of right-wing and 51% of left-wing extremists in the Analysen’s sample (Schmidtchen 1981). Once part of the group, perceived benefits, such as a chance to contribute to a greater good and acceptance into a community of the ideologically like-minded, anchored individuals to their new cause and comrades (De Ahna 1982; Neidhardt 1982b).

By championing narrow ideological perspectives on society and (international) politics, West-German extremist groups steered their members away from pluralistic discussion contexts, isolating them from alternative opinions while dissuading dissent by threatened exclusion or worse (Schmidtchen 1981). For the RAF in particular, the importance of the group, as well its hold over its members, became more pronounced after it went underground following the May 1970 liberation of one of its leaders from custody. Cut off from family and old friends, without jobs or educational enrollment (that could provide alternative sources of meaning or expose individuals to a variety of opinions), members increasingly relied on the group for their sense of identity and self-worth (De Ahna 1982; Jäger 1981). The practicalities of underground life, such as avoiding capture, finding safe houses and financing basic needs (generally through bank robberies), demanded 24/7 dedication from RAF members. Alongside the paranoia that made even conversations with supporters seem dangerous, these elements turned the RAF into an all-encompassing organization (Neidhardt 1982b).

On the run from the authorities and increasingly inward-looking, the RAF developed a dichotomous worldview with a steadily growing number of enemies (Neidhardt 1982b). Its own violence was justified on the basis of necessity; the only appropriate response to the United States’ imperialism in Vietnam and the only language that the German “Auschwitz generation” would understand (Aust 2017: 96). The group’s militancy was strengthened through frequent dehumanization of its opponents and made practicable by the paramilitary training that 11% of left-wing extremists, particularly among the RAF’s first-generation members, had undergone in Palestinian camps (Jäger 1981; Neidhardt 1982b; Süllwold 1981). The establishment of what Busher, Holbrook, and Macklin (2019) call a moral and strategic logic in favor of terrorist violence, also led to considerable tensions; both within the RAF and between its imprisoned, first-generation leaders and less scrupulous second and third generation members (Merkl 1995). This competition and conflict extended to the broader left-wing terrorist milieu, for instance between the B2J and the RAF (Neidhardt 1982b).

One chapter in the Analysen looks specifically at Aussteiger – individuals who disengaged from left-wing terrorist groups. De Ahna (1982) found that Aussteiger tended to have spent less time with the group and had fewer (serious) crimes to their name. Those who disengaged also appear to have found the personal costs of participation too high, as many abandoned their comrades after being arrested or when apprehension by the authorities seemed inevitable. This stands in marked contrast to the willingness to sacrifice their health and eventually their lives shown by the entire first generation of the RAF, who engaged in hunger strikes and eventually died by suicide while imprisoned in Stammheim (Aust 2017).

Social-movement and group dynamics were, thus, crucial to the emergence of West-German left-wing terrorism. Small-group dynamics, in particular, provide key insights into how individuals were first drawn and then anchored to groups like the RAF, subsequently adopting not only an extremist worldview but also engaging in, or supporting the use of, terrorist attacks. These concepts were also explored in the NITV dataset, though not always with similar findings (Table 3).

Table 3. Summary of group-level comparisons^a.

	Analysen	NITV
Variables Dataset(s)	LWEX (n = 223)	RWEX (n = 103)	Jihadist (n = 103)
	Prior to radicalization
Participation in illegal demonstrations	32%	–	–
Participation in legal demonstrations	25%	–	–
Participation in nonviolent activism	–	10%	7%
Participation in collective living	57%	0%	1%
Appeal of extremism/extremist groups	Noted, no figure given	49%	32%
During radicalization
Influence of extremist role models	51%	85%	92%
Paramilitary training	11%	48%	36%
Importance of extremist group-membership	Noted, no figure given	64%	46%
Decreased viewpoint diversity or cessation	Noted, no figure given	57%	76%
Decreased isolation or cessation	Noted, no figure given	15%	22%
Group/movement: violence morally legitimate	Noted, no figure given	39%	82%
Group/movement: violence strategically effective	Noted, no figure given	23%	68%
Notable peer pressures toward conformity	Noted, no figure given	75%	63%
Movement: Competition over ideology or strategy	Noted, no figure given	91%	74%
Group: Competition over ideology or strategy	Noted, no figure given	75%	34%
Dehumanization of opponents	Noted, no figure given	76%	71%
	LWEX (n = 223)	Involved in terrorist violence (n = 103)	Non-involved in terrorist violence (n = 103)
Fear of personal cost(s)	Noted, no figure given	9%	64%

^aThe comparisons in this table need to be contextualized. Please refer to the main text for applicable interpretations.

The prevalence of activist antecedents, as well as communal living arrangements, appear to have been specific to the West-German left-wing extremist context. In our own dataset, we found that only 10% of right-wing extremists and 7% of jihadists were involved in some form of nonviolent activism prior to their radicalization, and only one case had lived in a commune. Like the Analysen, however, some 49% of right-wing extremists and 32% of jihadists in our sample felt an attraction to extremist groups that preceded their actual ideological radicalization¹¹ (e.g., because neo-Nazis exuded a sense of danger and power, or because jihadists seemed to be the only ones fighting on behalf of perceived victims of injustice). In another similarity, 85% of right-wing extremists and 92% of jihadists were specifically influenced by extremists they looked up to as role models.¹² Similar again to the Analysen, our dataset suggests that the perceived benefits of group membership can tie members to these entities, propelling and prolonging the adoption of extremist worldviews and behaviors. References to the importance of the extremist group or movement were encountered in 64% of right-wing extremist cases and 46% of jihadist ones.¹³ Important contextual differences notwithstanding, extremist groups’ ability to attract and bind members to them, appears to function across temporal and ideological divides.

For many individuals involved in West-German left-wing extremism, the cost of that participation was markedly increased isolation and decreased viewpoint diversity. Only the latter of these trends is mirrored in our study; for 57% of right-wing extremists, their contact with people who held different or indifferent political views either decreased or ceased. Interestingly, at 76%, experiencing a decrease or complete cessation in viewpoint diversity was more strongly associated with the jihadist sub-group, X² (1, N = 197) = 9.30, p = .00, OR = 2.64, 95% CI [1.40 to 4.99]. However, in terms of isolation, both groups were not markedly different. During radicalization, only 15% of right-wing extremists and 22% of jihadists became more isolated in terms of the number of (close) friends or relatives, involvement in school or work, regular religious attendance and sports, club, or volunteer participation. For most of the extremists and terrorists in our sample, their radicalization did not significantly change their social ties. For some, radicalization also brought them new friends, associated activities like going to the gym or attending lectures together, and involved them in extremist social movements that offered opportunities for political activism like attending demonstrations and spreading propaganda.

Whereas decreased viewpoint diversity seems to be a fundamental characteristic of radicalization to extremism, increased isolation, in the sense of cutting ties with anyone but a small group of like-minded compatriots, is seemingly more context-dependent. Here, again, the particulars of West-German left-wing terrorism become apparent, as the physical isolation of groups like the RAF was strongly linked to their underground existence, something that the individuals and groups in our sample by and large did not enter into. For most of those in the NITV sample who became involved in terrorist violence, the outcome was either death or imprisonment rather than a chance to go on the run and launch further attacks from hiding. Arguably, the increase in Western states’ surveillance powers over the past decades makes prolonged terrorist campaigns, such as those undertaken by the RAF, exceedingly difficult (Hegghammer 2021).

Turning to group perceptions of the appropriateness of violence, some interesting differences emerge. While the Analysen provides no figures, it is clear that groups like the RAF developed an internal logic in which terrorist violence was morally justified and seen as an immediate, strategic necessity. Among the groups or movements that the right-wing extremists in our sample became affiliated with, only 39% saw political violence as unequivocally, morally justified. At 82%, this figure was more strongly associated with jihadists, X² (1, N = 201) = 35.26, p = .00, OR = 6.41, 95% CI [3.38 to 12.16]. Moreover, 68% of jihadists matched these convictions with the sense violence was the most effective mechanism for achieving success, whereas only 23% of right-wing extremists shared this position. Again, the unequivocal instrumentality of violence was more strongly associated with the jihadist sub-group, X² (1, N = 201) = 38.12, p = .00, OR = 6.54, 95% CI [3.52 to 12.15]. These findings suggest that radicalization does not necessarily lead individuals to see terrorism as unequivocally morally justified and strategically expedient. Radicalization is not a one-way path toward involvement in terrorism, and disaggregating the various radicalization-process outcomes, as some authors have recently begun to do (e.g., LaFree et al. 2018), is likely to yield a more nuanced understanding of the causes of terrorism.

Looking at how life in extremist groups affected their members, we found several similarities between the Analysen and NITV datasets. Peer pressures toward ideological conformity occurred in 75% of right-wing extremist groups and 63% of jihadist ones. Competition on ideological and (or) practical grounds within the broader extremist movement was encountered among 91% of right-wing extremists and 74% of jihadists, and significantly associated with the former, X² (1, N = 187) = 11.72, p = .00, OR = 9.28, 95% CI [2.07 to 41.83]. For those who became involved in a specific group, we found that intra-group competition over ideology or tactics was, again, more strongly associated with right-wing (75%) than jihadist extremism (34%), X² (1, N = 111) = 16.96, p = .00, OR = 6.00, 95% CI [2.45 to 14.67]. The frequency with which opponents were dehumanized was also notable: 76% for right-wing extremists, 71% for jihadists.¹⁴ This tendency was not strongly associated with one sub-group over the other. Stress, conflict, pressures toward conformity, and viewing opponents not just as people who hold different views but as barely human to begin with, thus seem recurrent features of life in extremist and terrorist groups.

The closest comparison between the Analysen’s focus on those who disengaged from terrorism and our own work is observed when we select on whether the extremists in our sample became involved in a terrorist attack or not. Just as the left-wing extremist Aussteiger were more likely to fear the personal costs of continued involvement, so too did 64% of extremists not involved in terrorist violence versus only 9% of those who did cross this threshold.¹⁵ In fact, when exploring the association between fear of the personal costs of involvement in an actual attack, our findings suggest that experiencing some form of marked fear is strongly associated with noninvolvement in terrorist violence, X² (1, N = 186) = 83.47, p = .00, OR = 0.03, 95% CI [0.01 to 0.08]. Of those who displayed trepidation at putting their convictions into practice (e.g., because they feared injury, death, or imprisonment), the majority remained non-involved in terrorist violence. These findings are another reminder that, across time and ideologies, radicalization processes are not predetermined to lead to terrorism. Many extremists appear to lack the depth of conviction necessary to actually risk life and liberty for their revolutionary cause.

Structural factors

Concluding this comparative assessment is a brief look at some structural-level influences on the emergence of left-wing terrorism in West Germany. The infamous shooting of student Benno Ohnesorg during a demonstration against the Iranian Shah in June 1967, and the assassination attempt on student leader Rudi Dutschke by a neo-Nazi in April 1968, clearly stand out as precipitant events, convincing hardliners that violent resistance had to move from theory to practice before it was too late. These incidents were preceded by years of escalating tensions and eruptions of violence between the police and protestors. In its turn, the development of an active and large West-German student protest movement during the second half of the 1960s, was linked to a lack of political alternatives to establishment parties. Many left-wing voters felt alienated by the social democrats’ willingness to enter into a coalition with the conservative Christian democrats. The German Communist Party had been outlawed in 1956, preventing radicals from having a voice in parliament. An extra-parliamentary opposition became a central element of the student protest movement, but was unable to achieve lasting influence (Claessens and De Ahna 1982; Neidhardt 1982b; Sack 1984; Steinert 1984).

As the student protest movement fractured toward the end of the 1960s, it left behind a legacy of failure to achieve change through either institutional or extra-parliamentary routes. West-German left-wing extremism therefore emerged against a backdrop of political marginalization. Another important structural-level theme was opposition to the U.S.-led war in Vietnam and West-German acquiescence in what was seen, certainly by many on the political left, as an imperialist endeavor. The centrality of the Vietnam war as a grievance was reflected in some of the RAF’s targeting choices (Neidhardt 1982b). The group’s violence in West-Germany could, to a certain extent, be seen as a form of “spillover” from the Vietnam war, drawing attention to the potential domestic consequences of states supporting or engaging in overseas military operations (Addison and Murshed 2005).

Turning to the NITV data (Table 4), precipitant events that spark an immediate sense of crisis and turn longstanding antipathy into outright hostility, remain influential, though not necessary, triggers for terrorist violence. Reorganizing our findings according to those extremists who became involved in terrorist attacks and those who did not, we found that for 42% of the former, precipitant events were present.¹⁶ In terms of “spillover,” the presence of violent conflicts involving the broader extremist movement, such as the Syrian civil war that broke out in 2011 and which fueled the rise of Islamic State, had a strong mobilizing influence. For 46% of our sample, overseas conflicts contributed to their radicalization. For those who planned, prepared, or executed a terrorist attack, conflict spillover factored into their decision-making in 59% of cases.¹⁷ This was mostly the case for the jihadists in the NITV dataset, which also makes clear that such conflict “spillover” is not a necessary condition for radicalization to lead to terrorist violence. Absent such violent overseas focal points, numerous right-wing extremists in our sample still engaged in terrorist attacks. Moments of crisis and marked antagonism, as well as the radicalizing potential of overseas conflicts, continue to be important, though not critical, elements of the broader backdrop against which extremism and terrorism take place.

Table 4. Summary of structural-level comparisons^a.

Variables Dataset(s)	Analysen	NITV
	LWEX (n = 223)	Involved in terrorist violence (n = 103)	Non-involved in terrorist violence (n = 103)
Precipitant events trigger terrorism	Noted, no figure given	42%	–
Conflict spillover influenced radicalization	–	51%	41%
		46% (overall sample)
Conflict spillover influenced decision to use terrorism	–	59%	–
	LWEX (n = 223)	RWEX (n = 103)	Jihadist (n = 103)
(Some) political representation at radicalization onset	Noted, no figure given	64%	4%
(Some) political representation as radicalization progresses	–	50%	0%

^aThe comparisons in this table need to be contextualized. Please refer to the main text for applicable interpretations.

In terms of political representation during radicalization, 64% of the right-wing extremists in our dataset felt existing parties (at least to some extent) represented their views, compared to only 4% of jihadists. As their involvement in extremism developed, these numbers dropped to 50% and 0% respectively. A lack of perceived political alternatives to violence, therefore, seems to describe both left-wing and jihadist extremists, but less so the right-wing extremist sub-sample. Limited or declining political representation formed an important explanatory variable in several other well-known cases of modern terrorism, such as the IRA in Northern-Ireland and the FLQ in Quebec (Kennedy-Pipe 1997; Ross 1995). At the same time, the relatively high prevalence of (some form of) political representation among the NITV’s right-wing extremism subsample, can be contrasted with rising numbers of attempted and completed terrorist attacks by right-wing extremists in both Europe and the United States in recent years (Jones and Doxsee 2020; Ravndal et al. 2021). Based on the evidence before us now, we tentatively conclude that extremism and terrorism commonly occur against a backdrop of limited or non-existent political representation, but that its presence is no wholly effective antidote against the emergence of terrorist violence.

Conclusion

Though affected by methodological issues, the Analysen remains a rich source of information on the individual, group, and structural-level characteristics of West-German left- and right-wing extremists and terrorists. When compiling our dataset on contemporary jihadist and right-wing extremists and terrorists across Europe and North America, efforts were made to address these methodological limitations, through more transparent sampling and data collection. However, these efforts were not infallible. To create a more accurate comparison on several variables, prevalence rates were calculated on both valid and invalid cases (i.e., including missing data, in line with the Analysen procedure). As noted in several earlier sections, data pertaining to the jihadist sub-group was more challenging to collect, and this must be carefully considered in its interpretation.¹⁸ When comparing the Analysen findings with our own, several tentative conclusions about the extent, strength, and consistency of the association between certain variables and involvement in extremism and terrorism more generally stand out. Broadly, the empirical findings fall into two categories of differences and similarities; the primary contrast is between extremists and terrorists separated by time and ideological affinity; the second contrasts, where feasible, extremists and terrorists with similar age-cohorts drawn from the general population.

Looking at differences and similarities among the populations covered by the Analysen and the NITV dataset, we found a considerable degree of variety in terms of educational achievements and socio-economic status. This suggests that radicalization to extremism and terrorism, in a Western context, may not necessarily stem from material or educational deprivation during childhood and adolescence, nor does it appear to be an issue encountered only amongst the underprivileged. We did find, however, that radicalized individuals tended to have higher unemployment rates than age-comparable cohorts of the general population. In the long-standing discussion about the relationship between deprivation and involvement in terrorism (e.g., Varaine 2020), we take a tentative middle-ground position; skeptical of childhood deprivation as a particularly salient risk factor, but keen to understand more about how unemployment at, or after, radicalization-onset affects this process and its outcomes. We believe that two mechanisms offer relevant insights. Firstly, in line with social control theory, relatively weak employment-related ties to society appear to be a common individual-level risk factors for radicalization, irrespective of its ideological character or the time-period in which it occurs (Hirschi 1969; Laub and Sampson 1993). Secondly, the gradual dissolution of work and education-related commitments appear to be an important enabling factor for the adoption of radically different worldviews. As one set of social bonds is loosened, the ability of extremist ideologies, movements and groups to determine someone’s perception of the world around them is strengthened (McCauley and Moskalenko 2008).

Another individual-level difference between non-radicalized peer groups and future extremists and terrorists, appears to be the likelihood of the latter experiencing family-related stressors, such as the death or divorce of parents. Such experiences have long been noted in the broader criminological literature as risk factors for involvement in delinquent behavior more generally (e.g., Farrington, Loeber, and Ttofi 2012). The precise role of childhood biographical stressors would be a fruitful avenue for future research. This finding also serves as a reminder that radicalization onset and outcome may be influenced by variables that can only be identified by using a broad temporal perspective, by treating radicalization as a process whose roots may lie beyond those immediately apparent grievances (Rottweiler 2021). We found extremists and terrorists no more likely than broader, non-radicalized populations to engage in delinquency, though differences may exist in terms of the severity of offenses committed. Regarding suicide attempts (the one mental-health related item on which the Analysen provide empirical data), we report rates broadly in line with similar age cohorts in the general population.

Our comparative analysis further emphasized how group-level factors in particular cut across temporal and ideological boundaries to form one of the key perspectives from which both radicalization to extremism, and involvement in terrorist violence can be understood. The attractions of extremist group membership, and such entities’ ability to both propel the adoption of violence-legitimizing worldviews and foster the common cause that enables their pursuit, remains a key element in explaining how larger, structural drivers of militancy can come to influence the behavior of individuals (McCauley and Segal 2009). While radicalization is an individual-level process, continued research into how extremist groups and movements, digitally as well as offline, are able to draw, retain and socialize their members, is likely to keep paying dividends when it comes to understanding future evolutions of the extremist and terrorist threat (Smith, Blackwood, and Thomas 2020).

At the structural level of analysis, we noted variety in terms of perceived political representation during radicalization. While left-wing and jihadist extremists generally lacked it, a small majority of right-wing extremists retained some sense of representation by political parties. Further exploration of what such perceived representation means for the willingness of extremists to (not) use terrorist violence, appears especially interesting. Both to ascertain how restricted political access can function as a risk factor for terrorism (Crenshaw 1981; Gleditsch and Polo 2016), and to better understand when perceived institutional routes to power can limit the willingness of extremists to escalate to terrorism (e.g., Bjørgo and Ravndal 2020; Da Silva and Sofia Ferreira 2020). The structural-level analysis also pointed to the role of (geo)political “flashpoints,” such as the Vietnam War or the more recent rise and fall of Islamic State, as catalysts for domestic radicalization and terrorism.

Beyond the results themselves, our study demonstrates the utility of comparisons that draw on multiple levels of analysis for studying the causes of extremism and terrorism. As the authors of the Analysen noted already, terrorism cannot be explained at the level of individual pathology (Neidhardt 1982a). It must, instead, be assessed against the broader context of social and political forces that shape motives and opportunities for the use of political violence, as well as the groups in which extremist views are propagated and turned from the abstract to the actionable. Context matters greatly, and each terrorist group will have characteristics specific to the time and place in which it originated. Finally, we argue that there is value not only in large-N samples when researching the causes of terrorism, but also in including variety in terms of time-period and ideological affiliation in these datasets. Only by placing contemporary forms of extremism and terrorism in a broader, as well as comparative, perspective, can we hope to better understand what drives individuals to engage with them.

Dataset availability

The NITV dataset and codebook are available at: https://doi.org/10.7910/DVN/NJX5BV.

Acknowledgements

The authors gratefully acknowledge support from NWO and Public Safety Canada and thank all interviewees for their time and trust, the Dutch Public Prosecution Service for granting access to privileged data on numerous Dutch terrorism cases, and the reviewers for their insightful comments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by Public Safety Canada [CRF 8000-21053]; and the Dutch Research Council [NWO, VI.Veni.191R.007].

Notes on contributors

Bart Schuurman

Bart Schuurman, Ph.D., is an Associate Professor at Leiden University’s Institute of Security and Global Affairs (ISGA). He has studied contemporary terrorism and counterterrorism from a variety of perspectives, including the role of public support in determining counterterrorism success or failure, the causes of homegrown jihadism and the state of the field of research. His current project studies the differences between individuals who radicalize to extremism but do not use terrorist violence, and those that do.

Sarah L. Carthy

Sarah L. Carthy, Ph.D., is a Postdoctoral Researcher at Leiden University’s Institute of Security and Global Affairs (ISGA) in the Netherlands. Her recent work has been in the area of radicalization, where she explored the potential for counter-narratives in the context of prevention. In her current role, she is working alongside Bart Schuurman on a multi-year, multi-region project on non-involvement in terrorist violence.

Notes

¹ Most English-language publications that reference the project are considerate of its various methodological shortcomings, but this has not always been the case (Corner et al. 2018; Crenshaw 1986; Merkl 1995; Victoroff 2005). Some of the empirically weakest parts of the Analysen have been cited without any acknowledgment of the limitations outlined above, fueling a body of work on the presumed abnormality of terrorists that emerged in the 1980s and 1990s (Corner and Gill 2022).

² Reference: 2019-012-ISGA-Schuurman.

³ “No” and “unknown” were treated as independent categories. If one coder marked an item as an “unknown” and the other marked the same item as a “no,” this was noted as “disagreement.”

⁴ Following Chen, Cohen, and Chen (2010), the statistic is interpreted as follows: OR <1.68 (very small); 1.68 to 3.47 (small); 3.47 to 6.71 (medium); > 6.71 (very large).

⁵ Using employment-status rankings found in Cörvers et al. (2017).

⁶ The remainder were either employed or in education.

⁷ Employment abandonment was not significantly associated with one conviction over another.

⁸ The high figure quoted in the Analysen partially reflects the extraordinary circumstance of fathers lost to the violence of World War II (Schmidtchen 1981).

⁹ Age cohort 14–16.

¹⁰ Here, there was a higher likelihood of missing data from older subjects. Including invalid cases, the percentages were 48% and 45% respectively.

¹¹ On valid cases only, the prevalence was 64% and 53% respectively, with a higher likelihood of missing data from the jihadist sub-sample.

¹² Our inclusion of at-a-distance role models accessed through the internet likely explains the high prevalence rates.

¹³ On valid cases only, the prevalence was 80% and 69% respectively, with a higher likelihood of missing data from the jihadist sub-sample.

¹⁴ On valid cases only, the prevalence was 90% and 86% respectively, with a higher likelihood of missing data from females.

¹⁵ On valid cases only, the prevalence was 75% and 9% (non-involved vs. involved), with a higher likelihood of missing data from the jihadist sub-sample.

¹⁶ Data were missing for 43% of cases. On valid cases, the prevalence was 74%.

¹⁷ On valid cases only, the prevalence was 47%, with a higher likelihood of missing data from the jihadist sub-sample.

¹⁸ This information is given in footnotes.