The reasons why people participate in political violence and terrorism remain a matter of contention. Scientific research has increasingly focused on this issue, but there is a lack of understanding of the overall findings of this body of research. One of the unexplored areas is the literature that used the notions of “radicalisation” and “extremism”. Probably the main obstacle to conducting systematic reviews of this body of research is the ambiguity of key terms such as “radicalisation” and “extremism”, which by their very nature identify a relative position on a continuum of opinions and behaviours. Some scholars even deny that radicalisation exists.
In a recent study that I co-authored with Ekin Ilbahar, Muhammad Iqbal and Greg Barton, we select and categorize all scholarly, peer-reviewed, English-language articles published between 2001 and 2015 that empirically investigated the factors of “radicalisation” into violent “extremism”.
This review findings suggests that radicalisation, in its fundamental mechanisms, so far as recent scholarly literature in English is a guide, is a cross-ideological and global process that entails similar fundamental categories of factors: 1- a political or social grievance (“push” factor), 2- a reward or appeal of violent extremism (“pull” factor) and 3- a personal vulnerability or predisposition (“personal” factor).
We also find important geographical and other differences in the frequency of the factors within the larger aggregate categories of “push”, “pull” and “personal” factors. In other words, the causes of radicalisation may differ in different contexts, even though the categories of factors are recurring.
Although the methods used in this field are getting more rigorous over time, there are still unanswered questions about the causal relations between factors and outcomes. For example, there is no definitive answer to the question whether the adoption of an extreme ideology precedes engagement in violence or it follows it. Moreover, certain push factors (such as poverty) and personal factors (such as demographic characteristics and personality traits) certainly precede radicalisation because of their nature, but others (such as the development of a mental disorder) might, at least in some cases, also follow or develop alongside radicalisation, being, in part, caused by it.
We propose that future research should aim to understand the interaction between push, pull and personal factors for both cognitive and behavioural radicalisation, and the specific conditions that develop the emergence of different types of those factors in certain contexts. A number of very important questions remain to be addressed. For example: do all push, personal factors have the same effect on the radicalisation process? What is the specific combination of personal, push and pull factors that triggers radicalisation in a specific context? Are there any differences in the push, pull and personal factors that predict cognitive and behavioural radicalisation? What factors are more important to identify the move to action?
We believe that these represent some of the most important questions that disciplined and theoretically informed empirical research should focus on, to move this field of scientific inquiry forward.