When we write about genocide, it’s customary to descend into paroxysms of inexplicability. Jeffrey Herbst of Foreign Affairs magazine marked this month’s 20th anniversary of the genocide in Rwanda with a typical display. “Despite the thousands of pages devoted to the Rwandan genocide,” writes Jeffrey Herbst in Foreign Affairs magazine, “we still do not have a good answer to the most basic question: Why?” It’s clear from the tone of this introduction that no clear answer will be supplied — though many words will be spent — and when the Foreign Affairs paywall kicks in after a few paragraphs, most readers will do as I did and click away. No need to pay $2.99 just to read the same old cliches.

It’s strange that Jeffrey Herbst thinks the genocide in Rwanda is inexplicable, since the political and psychological motivations behind the disaster are vividly and clearly documented in the massive historical record. The anguished “why” is a fraud — the question Jeffrey Herbst and so many other commentators are grappling with is not actually “why” at all. The question they’re really stuck on is this: “How can we live with the truth about why this happened?”. That’s the painful question nobody wants to ask.

The causes of Rwanda’s genocide are obvious to anyone who learns the history and analyzes the data points systematically. The same obvious causes can be seen in the other terrible genocides that shamed the 20th century, from Armenia to Nazi Germany to China, and in several genocides that are raging right now in Darfur and Central African Republic and Syria. We’re going to discuss these causes today. Our results will differ, though, from the weak pop-psychology answers embraced by common wisdom. The cause of the genocide will not turn out to be racial prejudice, or tribal hatred, or economic class envy, or repressed sexual aggression, or man’s inhumanity to man. We’re going to do a better job than that. And we’re going to be systematic about it by starting with Aristotle’s well-known list of four types of causes. To quote Wikipedia:

Aristotle held that there were four kinds of causes:

A change or movement’s material cause is the aspect of the change or movement which is determined by the material which the moving or changing things are made of. For a table, that might be wood; for a statue, that might be bronze or marble.

A change or movement’s formal cause is a change or movement caused by the arrangement, shape or appearance of the thing changing or moving. Aristotle says for example that the ratio 2:1, and number in general, is the cause of the octave.

A change or movement’s efficient cause consists of things apart from the thing being changed or moved, which interact so as to be an agency of the change or movement. For example, the efficient cause of a table is a carpenter, or a person working as one, and according to Aristotle the efficient cause of a boy is a father.

An event’s final cause is the aim or purpose being served by it. That for the sake of which a thing is what it is. For a seed, it might be an adult plant. For a sailboat, it might be sailing. For a ball at the top of a ramp, it might be coming to rest at the bottom.

This type of breakdown can be tricky to get the hang of, so before we dive in to genocide let’s calibrate by looking at a simpler and more familiar problem. What is the cause of drunk driving?

We can begin by brainstorming, by listing our common preconceptions that we might hear if, say, we held a town hall about how to solve an epidemic of drunk driving in our community. Let’s see: is drunk driving caused by the lack of police cars on the highway? That doesn’t sound right. Is it caused by too many beer commercials on TV? Too many bars and taverns existing near badly lit roads? Bad karaoke singing? Improperly painted yellow lines?

It’s clear that all of these answers are weak and deeply unsatisfying. So let’s do it Aristotle’s way:

What is the material cause of drunk driving? Aristotle is asking here for the conditions that must exist to cause drunk driving to occur. The material cause of drunk driving appears to be a society where alcohol is available and cars are freely driven. There is no drunk driving in, say, a strict Muslim or Mormon community that outlaws alcohol. There may be some slight semblance of drunk driving in a Chinese village where people own bicycles instead of cars, but the problem would be much reduced because you can’t do nearly as much damage if you’re drunk on a bike.

What is the formal cause of drunk driving? That is, what are the systematic principles that cause the problem to exist? The formal cause of drunk driving seems to be the fact that alcohol harms our dexterity and motor skills, that being drunk severely reduces our ability to drive a car safely.

What is the efficient cause of drunk driving? We are looking here for the most direct antecedent, for the thing we most commonly refer to simply as a thing’s “cause”. It seems clear that the efficient cause of drunk driving is alcohol. If alcohol did not exist, there would be no drunk driving. Given the fact that alcohol does exist, the fact that drunk driving occurs is nearly inevitable (even in a society with no cars, people will find something to drive drunk — horses, chariots, bicycles). The efficient cause of drunk driving is alcohol.

What is the final cause of drunk driving? That is, what purpose does drunk driving serve to those who engage in the act? Here is where the common answers above (too many bars and taverns near badly lit roads, bad karaoke, etc.) come into play. The final cause of drunk driving is the desire to get home after a night of drinking.

That was a useful exercise. Now, let’s talk about the cause of genocide.

The scope here is much wider and more complex and more tragic. The scope is also less familiar: we all have direct experience with alcohol and cars (hopefully not at the same time), but most of us have not been unlucky enough to have direct experience with genocide, so we’ll have to cite the historical record as we proceed.

Given those limitations, however, the analytic method is the same. We must try to think as clearly as possible here, and we must not shy away from the answers we find.

The material cause of genocide is a society engaged in a total war. As we’ve recently observed here, it’s a simple fact of history that genocide always occurs within the context of a bitter, divisive state of war. A small and well-contained war like, say, the American invasion of Granada in 1983 or Russia’s recent and easy takeover of the Crimea will not cause a genocide. History shows that genocide will occur only in the context of a war that is seen as deeply consequential, in which not only soldiers but civilians believe they are fighting for their lives and for the safety of their families, in which the consequence of losing the war is widely seen as tragic and inconceivable. Interestingly, even though history shows that there must be a state of total war for genocide to take place, the war does not have to be active. In the case of Rwanda in April 1994, it was the presence of the Tutsi-based Rwanda Patriotic Army poised to invade and take control of the Rwandan government that triggered the Hutu massacre of Tutsis.

The formal cause of genocide is the ability of a government or a military leadership to command large numbers of people to act. Every single genocide of the last hundred years has been a deliberate act of government or military policy. The fact that governments or military leaderships have the power to enforce policy — and the extremely sad fact that people will conform to murderous government or military decrees even when doing so violates their humane instincts or common sense — is the formal cause of genocide. In Rwanda in 1994, the formal cause of the genocide was the ability of a cabal of Hutu leaders and influencers (radio hosts, journalists) to stage a successful coup in Kigali, to distribute weapons and organize roadblocks, and to persuade Hutu citizens all over Rwanda that they must join in the defense against the invading Tutsi army by killing their Tutsi neighbors.

The efficient cause of genocide is, simply, war. Just as there would be no drunk driving without alcohol, history shows with absolute clarity that there would be no genocide without war. (Unfortunately, while most of us will easily agree that alcohol is the efficient cause of drunk driving, it is still not widely understood that war is always the efficient cause of genocide. This lack of public understanding is what I am hoping to correct with my recent flurry of blog posts about the subject.)

The final cause of genocide, sadly enough, is the pursuance of military advantage. Again, every single genocide of the last hundred years has been a planned and deliberate act. There has never been a case of a “spontaneous” genocide occurring within a community. Genocide is always an act of government or military leadership, and it is always carried out in order to further military strategy. In Rwanda in April 1994, the final cause of the the Tutsi massacre was obviously to disable the ability of the invading Tutsi army to establish power bases within integrated Hutu/Tutsi communities.

So, if it’s so easy to understand the causes of genocide, why do allegedly qualified commentators like Jeffrey Herbst (and so many, many, many more like him) continue to wax clueless about the meaning of atrocities like the massacre of 800,000 Rwandans in the spring of 1994?

I am not sure what the answer to this question is, but I believe the answer may have something to do with our romanticized notions of “good war”, and our sentimental attachments to our own military legacy. In the United States of America, we carry powerful images of General Eisenhower leading American troops in to liberate concentration camps from the Nazis (in fact, most of the concentration camps were liberated by Soviet armies, who were not much less genocidal than Nazi armies, but we carry the images around anyway).

Our emotional attachment to military propaganda cuts deep. If our own armies can prevent genocide, how can we comprehend the fact that militarism itself has been the root cause (according to every one of Aristotle’s four types of causality) of the problem of genocide? And how do we accept this fact without weakening our commitment to a strong military, and without insulting the legacy of militarism that plays such a prominent role in our national self-image?

Well, that’s why uncreative analysts like Jeffrey Herbst prefer to pretend that we don’t know the cause of genocide. It’s more polite that way.

Even Secretary-General Ban Ki-moon of the United Nations doesn’t appear to be willing to see the obvious fact that militarism is the sole cause of genocide. His own words in commemoration of the Rwanda disaster are as banal as anyone else’s:

I appeal to the international community to provide the military support urgently needed to save lives, get police back on the streets, and enable people to return to their communities.

Sure, more military support, that’ll help. And take another drink before you get in that car.