The other day a friend took me mildly to task for using the word “evil” in an otherwise ordinary conversation. Treating the notion as an essence, which he took it to be, is of course a classic example of pre-Enlightenment thinking. There is no Satan, no malign substance erupting into our lives and our history to corrupt what it touches and damn us to a hellish afterworld.

In my own defence, my use of the term is more practical and Durkheimian, used to signify the radical negation of morality in society that, paradoxically, provides the latter with its structural strength. Clearly the notion is socially constructed: as morality changes, so does its negation. But this isn’t a matter of sweating the small stuff: the word signifies a complete rupture, not merely contestation or “crossing the line.” The latter presents itself as comprehensible and, better, controllable. The former seems to escape both conventional discourses and understanding.

In this sense, Adolf Eichmann was evil, Paul Bernardo and Karla Homolka were evil, the shooter of young Malala Yousufzai in Pakistan was evil. The actions taken by these people are literally incomprehensible to us. We may look for causes, political and personal, but none seem sufficient to explain their actions.

The recent killings of two small children in New York once again bring this home to us. Here I offer a rare warning to readers—the article I have linked to is profoundly disturbing. In part this is because the writer doesn’t merely say the parents were “distraught” or “shocked,” but traces in some detail precisely what those adjectives, wan with overuse, actually refer to. The full, stark horror is borne in upon us.

As the article indicates, there seems to be no conceivable motive for this crime, although we may know more if and when the nanny, now under arrest and likely shackled to her bed in hospital, manages to revive.

I would suggest that it is this, more than the act itself, that inspires our immediate sense of dread.

The image I posted above is a popular one in our society to symbolize evil. A bat is not a bird, but a discomfiting caricature of one, not venturing out in sunlight but at twilight, that liminal area between night and day. It is associated with the drinking of blood and admittedly more benign infractions of order such as entangling itself in women’s hair. It doesn’t fly, it flits. It seems simply to emerge randomly from the dusk, as a living part of it, and vanish back into it.

Set aside what we actually know of these flying mammals. Stay with the image and its popular manifestations. Evil lives, it arises, it works in the dark, it has trajectories that we cannot comprehend or predict. It mocks our notions of order and explanation.

At every moment, we live in a world that can turn on a dime. A close friend suddenly reveals herself to be treacherous, hateful and unprincipled. Someone breaks into your house while you’re sleeping. You take an evening stroll in your neighbourhood, or have a drink in a bar, and get brutally raped by a stranger. There is a range here between the almost-banal and a major break with the ordinary.

Our first reaction is to explain. Why did this happen? Did I do something to offend the friend? Did I fail to lock up properly? Should I have been more careful?

We want to live in a web of rational explanation into which we can fit these events—to literally make sense of them. Our sense of order upon which society is apparently founded depends upon it. But we are constantly reminded that this order is precarious, and seems to rest upon no foundations at all.

Faced with the enormous brutality and depravity of the Moors murders in the UK, Pamela Hansford Johnson zeroed in on the killers’ tiny library, full of porn and sadism, and subsequently wrote her treatise On Iniquity. While she didn’t advocate out-and-out censorship, she was concerned that such books encouraged an “affectless society” that buried empathy, and she wanted strict limits placed upon their circulation.

She might well have been right to some degree, but it is clear that a book collection does not in itself determine who will, or will not, be a child torturer, rapist and killer, and that separating causation from correlation is nearly impossible.

We just don’t know, in other words, and worse, there may be nothing to know. When the Russell Williams affair broke two years ago, no reasons for his evil were immediately obvious, and they aren’t to this day. People scrambled to find clues in his past life to explain his unspeakable crimes. The notion that there might be none was something that no one wanted to contemplate. At the very least, there had to be the possibility of an explanation, whether we ever found it or not.

It is a commonplace that many female victims of sexual assault blame themselves for what happened to them. A misogynistic culture reinforces this recurring self-critical narrative—but it isn’t the whole story.

What terrifies and transfixes us about these ruptures, large and small, is not the sudden act to which any of us might fall prey. It’s that there may be literally no reason for it. In that moral abyss in which we hang suspended, an island in a chaos thrown open to our imagination by dark and motiveless acts, the ordered world of society is revealed as vulnerable and illusory. Punishing the evil-doers is the least of our problems. We should, and we do, to the best of our ability. But what can we do about evil itself, that rupture occurring without warning in the very heart of our well-ordered social refuge?

Probably nothing. And that throws all of our comfortable assumptions, right, left and indifferent, into question.