ALLOW ME to describe a familiar course of events. Somewhere in the world, extremists carry out a terrorist attack in the name of Islam. In the days and weeks following, a series of opinion pieces are published either attacking Islam for violence or denying it bears any responsibility.

Critics may note that terrorists who carry out murderous acts routinely cite Islam as their justification; that the Koran is full of brutal content; that polls have repeatedly shown alarmingly violent beliefs and attitudes in significant minorities of Muslims around the world; and that the world is long past the point where we can afford not to criticize harmful religious beliefs.

Defenders may note that the vast majority of Muslims are not militant extremists; that there are great differences of belief among Muslims; that it is bigoted to draw conclusions about all Muslims based upon the actions of a small minority; and that many Muslims sit at the forefront of the fight against Islamic extremism—both as activists and as its primary victims.

After a while public attention turns to other things, but then another attack occurs and a new series of commentaries are published on the topic. As for the conversation, it goes largely nowhere. It just repeats itself in well-worded prose with each new terrorist act.

What’s common to both sides of this intellectual tennis match is a simplified way of thinking about causality. Let me illustrate using the words of CNN host Fareed Zakaria. Writing in his Washington Post column last fall, Zakaria argued that violent extremism cannot be due to anything intrinsic to Islam. And why not? Because, as he learned back in graduate school,

…you can never explain a variable phenomenon with a fixed cause. So, if you are asserting that Islam is inherently violent and intolerant—“the mother lode of bad ideas”—then, since Islam has been around for fourteen centuries, we should have seen fourteen centuries of this behavior.

Citing research by Zachary Karabell, Zakaria argues that there simply hasn’t been fourteen centuries of extremist violence and intolerance in Islam. In fact, Islam has shown itself to be more peaceful and tolerant at times than Christianity over the same period. Ergo, Islam cannot be the reason why there is a problem with Islamic extremism, and there is something deeply mistaken in the views of critics who say otherwise.

Although this argument might sound convincing, allow me to persuade you otherwise. First, Zakaria isn’t wrong that a single fixed cause like the revelation of Islam may have an impossible time explaining a variable phenomenon like Islamic violence and terrorism. However, a fixed cause can still be an integral part of the overall explanation of a variable phenomenon.

Imagine that a man crashed his vehicle after driving home on a familiar stretch of road between his house and a local bar. As the crash investigators later examine the scene, they note that he had recorded a blood alcohol level well above the legal limit and that it had been raining on the night of the accident. They also know from a previous report by civil engineers that the crash took place on a problematic corner. The curve of the bend and a dip immediately before it were deemed unsafe, and plans were before local authorities to redesign the road’s layout.

If we accept Zakaria’s reasoning, we should discount the corner as a factor in causing the accident because it was present on every occasion (it was “fixed”). Yet this would make us horrible crash investigators who should be fired immediately. Yes, the corner was there all along, including at all the times the man did not crash. However, that doesn’t mean the properties of the corner didn’t combine with the alcohol and the wet road surface to cause the crash on the night in question.

Zakaria’s treatment of the issue is quite simply too simple. It is entirely possible for Islam’s revelation to be a part of the reason why we see Islamic violence and terrorism in the modern era even though the religion itself has produced only variable levels of it over the course of 1,400 years. Indeed, there appears to be no other way of explaining the modern problem without it.

By necessary extension, though, anyone who thinks that Islamic violence has a direct and easily traceable path back to the content of the Koran is also in trouble. They are in no better position than someone who points to the dangerous corner and, understanding it to be dangerous, overlooks the man’s consumption of alcohol and the rainy night. Such a person should be let go as a crash investigator, too.

The connection between Islam and violence is unsurprisingly complex, and a fuller explanation of the problem needs to reference other things, including individual psychologies, an established subculture of violence within the Muslim world, and the political and socioeconomic realities that some Muslims live within.

In addition to these other causal factors, it should also be recognized that there is considerable praiseworthy moral content in the Koran, and that the vast majority of Muslims are far removed from those who would execute French cartoonists on the streets of Paris. Still, the link between Islam and violence is not imaginary, and it should not be ignored simply because it is painful and regrettable to admit.

In the language of our analogy, Islam is a road with an unsafe corner, and while most of the people driving on it are excellent drivers with mechanically sound cars, not all of them are. Some are driving terrible cars, some have poor vision, some have been drinking, and some are driving at night. Within a population as large as one and a half billion people, it’s to be entirely expected that some will crash on that corner in the road. Productive dialogue concerning Islamic extremism must focus on educating and assisting those who travel upon it.

Read all articles in this issue’s Paris Perspectives series.