Causes of terrorism: “It’s religion!” “It’s mental illness!” “It’s political grievances!” Or, “It’s America!” In the words of Ramzan Kadyrov, Head of the Chechen Republic, commenting on the two Chechens suspected of carrying out the terrorist attacks at the Boston Marathon: “They grew up in the U.S., their attitudes and beliefs were formed there. It is necessary to seek the roots of evil in America.”

Having served two years as an interrogator at Guantanamo Bay, worked counter-terrorism issues as a staff member in the Office of the Secretary of Defense, and now as a professor who teaches future military leaders about religion and violence, I have spent years encountering how the causes of terrorism are complex and interrelated. But since 9/11, the media have been especially replete with over-simplified explanations of the causes behind terrorist violence, continually trying to peg these attacks on one particular cause or another, as if individual causes were mutually exclusive.

As we begin to learn more about the Chechens identified as suspects in the Boston terrorist attack, I suggest a tool for considering the complex causality probably at work here.

Complex causality is what we need to grasp if we are to understand how the interaction of multiple factors can escalate individual and group actions to the point of international terrorism.

Start your day with Public Discourse

Sign up and get our daily essays sent straight to your inbox.

This tool applies also to understanding how radical ideologies with religious elements can influence one religious believer to commit violence, while leaving unaffected other believers of the same religion. When some religious believers are not violent, people are quick to absolve that religion of any connection whatsoever to violence. Yet throughout history, across continents and cultures, from one religion to the next, religiously based narratives escalating causes to a sacred, cosmic level have been a motivating influence for violent actors (as well as for peacemakers).

I introduce this tool to help us consider how different types of information relate to each other. This is a model I borrow from plant pathology. Plant pathologists use a model they call the “Plant Pathology Triangle.”

The key to understanding this model is the notion that pathogen and disease are not the same thing. A pathogen alone does not cause a disease, and diseases are the real problem. Thus we need to understand the environment and the host that allow the pathogen to become a disease.

Consider the pathogen Phytophthora infestans. This pathogen caused the Irish potato famine in the mid-1800s. Under the right conditions it is deadly, very deadly. Under the right confluence of circumstances, it is the cause of a fatal disease called “late blight” which kills tomato and potato plants. But while this pathogen persists today, you probably ate a tomato or a potato within the past week; the disease is not omnipresent.

The pathogen Phytophthora infestans by itself is only a pathogen, no more. A pathogen only causes a disease when the environment (e.g. rain, wind) makes it possible for it to travel to a host (e.g. tomato or potato plant) that is susceptible. Disease results when there is a confluence of the right pathogen, a susceptible host, and a pathogen-friendly environment.

Variables on this abound, and another way to consider this is by adding a fourth variable of time: taking into account how long the pathogen can live, how long it has contact with the host, etc.

I view toxic ideologies as somewhat similar to pathogens.

By toxic ideologies I mean the belief systems and narratives that terrorists tell themselves about who they are and why they act. Adding elements of the sacred and cosmic level into such a narrative can increase its power, sometimes even its toxicity. Yet these ideologies alone do not result in terrorism.

For example, toxic ideologies such as those of al-Qaeda and its sympathizers do not necessarily lead to terrorism. I for one have read many texts and listened to terrorism advocates espouse such ideologies, and yet I feel no inclination to dedicate my life to acting upon them. I am not a host in which such “pathogens” adhere, plus I live and work in environments with robust countervailing tendencies.

The two suspects in the Boston attacks are from Chechnya, an area of the world packed with political, cultural, and religious complexities, and they have lived lives of international displacement. We need to consider all of this, as well as who they were as individual human beings (“hosts”), in trying to understand these attacks.

When Ramzan Kadyrov blames living in America, which he seems to consider pathogenic for leading these young suspects to terrorism, we might consider that there are millions of people raised in America who do not become terrorists. So it would seem that growing up in America is not a sufficient cause for becoming a terrorist.

Some have suggested that the cause could be solely political, blaming grievances against the highly problematic political situation of Chechnya, where Chechen nationals have carried out attacks. Yet Chechens suffered horrific injustices under Stalin without resorting to international terrorism, so again, a single issue alone does not show itself to be sufficient as a cause.

And then there is the video posted by Tamerlan Tsarnaev, the suspected terrorist who was killed Friday morning, extolling a statement by Muhammad considered prophetic by Muslims, and especially popular among modern violent extremists using Islamist ideologies. Others may jump to claiming that Islam per se was the cause, which does not make sense because there are over a billion Muslims in the world who neither carry out nor even support terrorism.

We must get beyond inaccurate causal over-simplification and consider the phenomenon of terrorism as a complex interplay of multiple factors.

Moving beyond the over-simplification of single-causality thinking is not a way of dismissing suspected causes, but rather a means for understanding how suspected causes may have intersected with each other. This not only makes it possible to understand the partial contributions of certain causes for a particular individual; it also frees our minds to think more creatively, on more fronts at once, about future prevention.

The plant pathology triangle model was never meant to be applied to terrorism, nor do I make any claim that it is a perfect fit for explaining causes of terrorism. However, it can provide one way of visualizing causality to help increase attention to complex causality, which I would argue is the norm, not the exception, for terrorism.

Jennifer S. Bryson, Ph.D. is a Visiting Research Professor in the Peacekeeping and Stability Operations Institute at the U.S. Army War College in Carlisle, PA.