In international relations the concept of terrorism usually always boils down to Islamic radical terror. Few other categories of terrorists operate internationally; therefore, most of the literature centers on violent Islamic Jihad. So what are the causes? How can we make sense of terrorists’ motivations. Below is a quick rundown of the various themes in international relations literature.

First, note that there is no universally accepted definition of terrorism. These explanations should fit most definitions. Second, the literature is chock full of many explanations, and the best hypotheses usually include elements of multiple explanations.

A Constructivist Explanation

The constructivist explanation asks, what’s the software in the terrorist’s head? How do they see the world? How is their lens constructed? Constructivism as a theory rejects the concept of objective reality. This explanation is about terror groups’ perceptions. Many terrorists have a negative view of the West, believing the West—specifically the US—is trying to undermine Islam. This lens stems, in part, from their experiences with colonialism, where, often times, traditions and customs were derided by Western mercantilism and religious values. Holy Islamic sites are trampled by filthy, evil Americans. Operation Desert Shield was not to protect the sovereignty of an ally, but to belittle the traditional values of an entire religion. They also see local leaders, such as the Saudi Royal Family, as being in bed with Western colonial interventionism. And because of this, violence is a just response.

Of course, this view is marred by difficulties. If you cannot understand terror without understanding how terrorists’ lenses are constructed, then it cannot be a generalizable theory. Furthermore, it’s vulnerable to cognitive biases. You see what you expect to see, and therefore the lenses become more rigid, and it’s difficult to adjust your views with additional information.

A Deep Historical Explanation

This explanation suggests something went horribly wrong in the Muslim and Arab world. This is the Bernard Lewis (What Went Wrong?) approach. At one time the Muslim World was the driving global force for intellectualism. During the middle ages Baghdad was the capital of the Islamic Golden Age. Thanks to intellectually noble Islamic and Arab scholars, many of the Greek texts survived, translated into all the languages of trade. Mathematics and astronomy flourished. And its momentum finally inspired the rebirth of Europe. But the Islamic and Arab world went from the apogee of global leadership to a massive descent over several hundred years. This deep macro, historical explanation explains why Muslim societies still struggle. The effects continue to linger, and terrorism is merely an expression of the intolerable suffering which a quarter of the planet is forced to tolerate as the world moves on without them.

A Twin Motivation Explanation

This is the Clash of Civilizations. You have the near and the far enemies. In the Muslim World Riyadh is near and Washington, DC is far. Terrorism therefore has two motivations. Near enemy terrorists focus on apostate countries (Egypt, for example), heretical countries, and countries deserving of death. Initially al Qaeda focused on the near. Bin Laden’s hatred of the Saudi family as heretics drove him to attack locally. But over time he turned his attention to the West, as the head of the culturally inferior snake. From bin Laden’s, and to a much larger degree ISIS’s, perspective, a civilizational conflict is welcome, necessary, and foretold in the holy texts. Terrorism is merely self-fulfilling prophesy and doing what you must.

A Failed State Explanation

Failed states are states where the governing body essentially loses control of or diminishes its capacity to affectively administer large portions of their territory. Somalia is the best example we have, but also Iraq, Syria, and Afghanistan. Lawlessness and insecurity promote mass human migrations. Refugees and internally displaced persons struggle for basic survival needs. Terror organizations thrive in such environments, sometimes feeding off the insecurities of vulnerable people, able to recruit normal civilians with promises of security, wealth, and immortality. On the other hand they might offer death to people who turn down their recruitment offers. And the government is powerless to stop it. This explanation might be suited for an undeniable reality: Most Islamic terrorists are highly educated, middle class people. Why have so many engineers and medical doctors joined ISIS? Maybe it’s because the fear of losing everything was overcome by people who could give them money, power, and prestige and murder anyone who scoffs at their proposal.

A Strategic Actor Explanation

Essentially this explanation proposes terrorists are cross-benefit calculators. Terrorism serves their strategic goals. For example, terrorists are not aggrieved. They are not injured by the collapse of their civilization. They are proud of their past and want their empire back. And terrorism is an attractive way to accomplish this goal. We can take this further and say terrorists view themselves as superior, and terrorism allows them to aggrandize before a public audience.

A Blame-the-West Explanation

So far I’ve only provided you with internal reasons. But what about external forces? Are we to blame? Don’t take this to mean I sympathize with terrorists or blame Americans or Europeans. No, I’m merely stating the obvious; we do things in the Arab World that harm people. Under this explanation, terrorism is a response to Western Occupations (see Robert Pape). Our foreign policy is venom in the Middle East, and America likes to invade the social space of others and poison everything, especially when uninvited. The American ideal of exceptionalism doesn’t play well on fringes of Muslim world. The US’s relationship with dictatorial monarchs and Israel makes the US a target. And the US needs to get the hell out of the Gulf (see Michael Scheuer).

A Western Role and Globalization

This is an indirect effect on behavior. Basically, Western-driven globalization runs up against conservatism. Conservatism is about keeping traditions. Globalization is a liberal ideal that promotes progress. As the world becomes smaller due to Western-driven globalized efforts and increased international interconnectedness, civilizations’ traditional values are undermined and diminish, and die hard adherents are scoffed at by the international community. The actions of the West trying to leave the past in the past and to forge a more connected world elicit strong reactions from people who were fine with the way things used to be in the good ol’ days.

Other Basic Explanations

Education Levels

While terrorists tend to be educated, there’s a strong correlation between low education and effective recruiting. Uneducated people are more likely to accept jobs of terror.

Poverty

Similarly, although the literature has not yet reached a consensus, it could be that extreme poverty plays a role. On the other hand, the Arab World is significantly more wealthy than Sub-Saharan Africa, and we don’t see many Namibian terrorists.

Oil

While it’s debatable how oil plays a role in terrorism, it’s undeniable that it does.

Humiliation

This one might be slightly controversial, but some terrorists might be lashing out after being humiliated. Bin Laden was mocked by the Saudi Royal Family and stripped of his citizenship. He was then exiled to Sudan (and he really hated the Sudanese culture and climate). He carried this humiliation around with him as a driving motivator to attack Saudi Arabia. When this was impossible, he turned his attention to the Saudis’ most trusted ally, the US.

Mental Illness

This one is especially liked in the American Conservative Parties. And it is certainly the most controversial on this list. But there could be some merit to it. For example, forensic psychologist Stephen Diamond once analyzed bin Laden (not in person), finding the terrorist leader probably had a messiah complex. Furthermore, he was pathological—a psychopath. Similarly, political psychologist and psychiatrist Jerrold Post argues terrorists tend to receive pleasure as their kill count increases. This is a symptom of a personality of dissociation. Of course, dissociation is not inherently a mental illness. Surgeons must dissociate themselves from their patients’ pains. We don’t want doctors holding scalpels to flinch every time they cut into someone. But the ability to dissociate from pain in order to gain pleasure from killing people is concerning.

So There You Have It

There could be any number of other explanations, and none of them are mutually exclusive. If you have any additional ideas, feel free to let me know.