We have so far documented the existence of a positive correlation between Islamist attacks and GT . To establish a causal link, we resort to an instrumental variables approach. To this purpose, we must build on an exogenous source of variation of the volume of online queries for our sensitive keywords. The scope for our search is limited, as measures of the instruments must be available with monthly frequency across the world. To address this issue, we focus on the impact of natural and technological disasters. There is evidence that disasters exogenously prompt a strong behavioral response in the public, for example by aecting religious beliefs (Belloc et al., 2016), time preferences (Callen, 2015), risk attitudes (Hanaoka et al., 2018), and support for redistribution (Gualtieri et al., 2019).
Following Jetter (2017; 2019) and Jetter and Walker (2018), we assume that catastrophic events monopolize the attention of the media and the interest of the public, thereby lowering the relative query volume for our sensitive keywords. This assumption is consistent with
evidence that natural disasters compete with other newsworthy stories in getting media coverage and catching the curiosity of people (Eisensee and Strömberg, 2007). This implies claiming that there is no way through which disasters aect terrorist attacks other than the reaction they prompt in the attention of the public. It is reasonable to assume that natural disasters randomly harm the military capacity of terrorist groups and counter-terrorist forces.
Moreover, as disasters are exogenous, terrorist organizations cannot accordingly schedule their missions in advance to avoid overlapping and competition with other stories in the media coverage of the attacks (Jetter, 2019).
The Centre for Research on the Epidemiology of Disasters (CRED) at the Université Catholique de Louvain (UCL), collects data on catastrophic events worldwide with a daily frequency into the Emergency Events Database (EM-DAT).21 The random occurrence of disasters provides a monthly, exogenous, source of variation of our explanatory variable. Our instruments are two dummies equal to one if a natural or a technological disaster occurred in country c at time t. The results reported in Table 7 suggest that the instrumental variable approach supports our main ndings. Google searches for sensitive keywords signi cantly and positively correlate with the number of Islamist attacks.
However, there are reasons to handle this nding with caution. The estimates only regard those countries that faced at least one disaster where at least one Islamist attack occurred over the 2004-2015 period. The intersection between the two sets reduces our sample to 58 countries. The rare occurrence of natural and technological disasters in many of the countries hit by Islamist attacks yields a limited variability of the instruments. Also, there are circumstances under which our assumption on the exogeneity could be challenged.
For example, disasters could harm the State's capacity to react to attacks by requiring the deployment of military forces for civilian purposes. This circumstance may perhaps encourage terrorists to expedite scheduled missions. Even if we nd no proof of such a mechanism in our dataset, we need further information to validate the orthogonality assumption de nitively.
21See: www.emdat.be
Table 7: Instrumental variable approach
DCCE-IV
GTt 1.708*
(0.929)
IAt−1 0.157***
(0.030) Sargan statistic Chi2(53)=24.332
(0.999)
# Observations 8,236
# Countries 58
Notes: The dependent variable is the number of islamist attacks. Standard errors in parentheses, ***, **, and * denote, respectively, 10%, 5%, and 1% signi cance levels.
6 Discussion
Our panel analysis reveals a systematic relationship between Islamist attacks and online searches for a set of sensitive keywords over the period 2004-2015 worldwide: online searches signi cantly and positively relate to attacks. Dierent kinds of user may search for some of the keywords we employ in the empirical analysis, from students who want to deepen their knowledge of political Islam to journalists and scholars interested in researching violent extremism. Online searches may also detect the celebrity of terrorist organizations. However, we also use keywords explicitly denoting an attraction for fanaticism and violence that are likely searched by sympathizers of the jihad.
Distinguishing between keywords allows us to better understand the positive relation-ship between Google searches and the attacks. We divide our set of 47 keywords into two groups. The rst group contains the keywords with an average monthly frequency higher than 500 searches in the UK. Such searches are not explicitly violent and mostly regard
po-litical Islam. The SERP analysis conducted by Ahmed and Lloyd George (2016), however, shows that these seemingly non extremist searches often return extreme content aimed at promoting radicalization among Internet users explicitly. The second group contains more extreme queries, which are mostly related to violent extremism and systematically lead to fundamentalist, militant and explicitly violent content (Ahmed and Lloyd George, 2016).
We nd that the online searches for both groups of queries are signi cantly associated with the attacks. The coe cient for the popular keywords signals that the celebrity of terrorists among the public is signi cantly and positively correlated with the attacks. This result is consistent with previous evidence suggesting that media coverage and celebrity encourage terrorists to plan new missions (Jetter, 2017; 2019; Frey and Osterloh, 2018; Jetter and Walker, 2018). The signi cant and positive coe cient of the queries for the extreme keywords, on the other hand, supports the interpretation that online searches may detect not only the celebrity, but also the popularity of the extremist message. The spreading of curiosity and sympathy for radical Islam and violent extremism may signal the formation of a fertile ground for radicalization. The fact that, through search engines, potential sympathizers easily come into contact with the jihadi propaganda, may further nurture extremism triggering a cycle of radicalization. Rearranging the keywords into dierent groups based on their meaning allows us to understand the relationship between the interest in Islamist extremism and the attacks more in depth. This part of the analysis reveals that attacks are more signi cantly and sizably associated to keywords evoking violent actions, such as beheadings, or explicitly related to the Jihad, such as Abdullah Azzam. Beheading was a method of execution in pre-modern Islamic law. Jihadist organizations use beheading as a method of killing captives. Since 2002, groups such as Al Qaeda and ISIS have been mass broadcasting beheading videos as a form of propaganda (Campbell, 2007). Abdullah Azzam was a Sunni scholar, also known as the
Father of Global Jihad (Edwards, 2017). Despite having laid the foundations of Al Qaeda and being considered as the spiritual mentor of Osama Bin Laden, Azzam is not as known to the general public as his disciple. He died assassinated in 1989, well before the rst spectacular
actions of Al Qaeda, and his name mostly circulates among researchers and sympathizers of the global jihad doctrine (Maliach, 2010). The nding that the online searches for such speci c keywords signi cantly correlate with the occurrence of Islamist attacks is striking and calls for a more profound investigation into the transmission mechanisms that could allow the popularity of extremist groups to turn into support and feed radicalization.
The limited variability of the instruments and possible exceptions to the assumption of their exogeneity suggest caution in interpreting our results as causal. Despite this limita-tion, our work improves the understanding of the relationship between terrorism and the active interest in radical content. Previous studies suggest that the media coverage of violent actions feeds further attacks, as having the public's attention encourages terrorists to plan new missions. Our approach oers a way to uncover the attention of the public to violent extremism, and documents that people's interest in the terrorists' message is indeed signi -cantly associated to the attacks. The association is even stronger for searches likely denoting a propensity for violence and support for the jihad. Measuring such a fatal attraction could help detecting, and perhaps preventing, the spreading of sympathy for terrorist ideas.
7 Conclusions
In this paper, we propose a new approach to investigate the relationship between the pub-lic's attention to radical Islam and terrorist attacks. The empirical analysis documents a link between the online searches for a group of sensitive keywords and the occurrence of Islamist attacks. Through dierent model speci cations we show that Google searches for the selected keywords positively correlate with attacks in a panel of countries over the period 2004-2015. Overall, our evidence suggests the possibility that growing interest in violent ex-tremist content may reveal a substratum of public opinion potentially favorable to individual radicalization.
Our ndings extend a small but growing literature studying the relationship between the
media and terrorism. Previous studies mostly focus on the role of social media and the press coverage of terrorist missions. We add to this eld by highlighting the usefulness of also focusing on the general online landscape that users can access through search engines and employing a new method for detecting the public's interest in radical Islam and violent extremism. The literature has shown that attacks more likely occur when terrorists expect the media to give enough coverage to their actions as the attention of the public brings new opportunities for gaining followers and nurturing radicalization among potential sympathizers (Rohner and Frey, 2007; Jetter, 2017; 2019). We uncover the attention of the public to radical Islam and violent extremism and show that it is indeed systematically and robustly correlated with attacks perpetrated in the name of Islam by self-proclaiming Islamist groups.
Previous literature on radicalization has often focused on the detection of the jihadi propaganda on social networking sites. Our research urges the need to also focus on the decentralized provision of information on the world wide web. Monitoring the broader online landscape helps in detecting the active attention of the public to extremist ideas. Knowing how interest in violent extremism is spread among Internet users is essential not only because it provides a measure of the exposure of the public to violent and illegal content, but also as it may signal the sedimentation of a substratum of sympathy for terrorist claims susceptible of turning into a ground for radicalization. Given previous evidence on the impact of media coverage on the popularity of terrorists, our results call for further investigation on the possibility that the attention raised by the attacks in the media and their audience could fuel a cycle of violence. By raising media coverage and catching the attention of the public, terrorist attacks could awake dormant sympathizers whose radicalization may, in turn, feed new attacks.
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Appendix
A.1. Glossary
The de nitions provided hereafter are sourced from the ARDA (Association of Religion Data Archives)22 and Wikipedia, and are marked by an (A) and (W), respectively.
Abdullah Azzam: (1941 - 1989) also known as Father of Global Jihad, was a Palestinian Sunni Islamic scholar, theologian, and founding member of Al Qaeda. (W)
Amaq Agency: is a news outlet linked to the Islamic State of Iraq and the Levant (ISIL), it is often the rst point of publication for claims of responsibility by the group. (W)
Apostasy: Departing or falling away from a religious faith. (A)
Apostates in Islam: Apostasy in Islam is commonly de ned as the conscious abandonment of Islam by a Muslim in word or through deed. It includes the act of converting to another religion or non-acceptance of faith to be irreligious, by a person who was born in a Muslim family or who had previously accepted Islam. The de nition of apostasy from Islam, and whether and how it should be punished are matters of controversy among Islamic scholars.
(W)
Ayman al-Zawahiri: (1951 - ) is the current leader of Al Qaeda (assumed o ce in 2011).
(W)
Caliphate: an Islamic state under the leadership of an Islamic steward with the title of caliph (Arabic: khal fah), a person considered a religious successor to the Islamic prophet Muhammad and a leader of the entire ummah (community). (W)
Crusades: Medieval military campaigns of the eleventh through fteenth centuries waged by Christians to recapture Jerusalem from Muslims. (A)
Crusades: Medieval military campaigns of the eleventh through fteenth centuries waged by Christians to recapture Jerusalem from Muslims. (A)