Schopenhauer Got Evil Backwards—Here’s Why Aquinas Was Right

I’m currently reading an advanced copy of

Andrew Klavan

’s new book The Kingdom of Cain: Finding God in the Literature of Darkness.

So far, it’s excellent.

Early on, Klavan takes up the difficult question of how to define evil—what it is and how we should understand it. In doing so, he engages with various thinkers, including Schopenhauer, who wrote: “the concept of right contains merely the negation of wrong.” In other words, Schopenhauer suggests that what we call “right” isn’t something real or positive in itself—it’s simply the absence of wrong.

Klavan ultimately rejects this view, and in this article, I’d like to explain why he’s right to do so. According to St. Thomas Aquinas, it’s not wrongness that comes first, but rightness. Good is primary. Evil is always a privation—a lack of the good that ought to be there.

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In the Summa Theologiae I, Q.48, A.1, Aquinas asks: “Whether evil is a nature?” He considers the objection that evil must be a nature, because the Philosopher (Aristotle) says, “good and evil are not in a genus, but are genera of other things.” (Which basically means that good and evil aren’t categories of things themselves, but ways of describing things in other categories—like actions, qualities, or beings). But Aquinas replies:

“Evil is not a being, but the absence of being. And hence evil is neither a genus nor a species, but rather a kind of non-being.”

At this point you might be tempted to misunderstand him. Aquinas is not saying that evil isn’t real. It is. But its reality is parasitic on the good—like rot in wood or a hole in the carpet. A hole is “real,” but it doesn’t have existence in itself. It’s the lack of what ought to be there.

He writes:

“Evil is the privation of good… and thus evil is not an essence or nature but a defect.”
(ST I, Q.48, A.1, ad 1)

Aquinas illustrates this with examples from physical defects. Blindness, for instance, is a kind of evil—but it’s not a “thing.” It’s the absence of sight in a creature that ought to have it.

Physical Evil vs. Moral Evil

Aquinas distinguishes between physical evil (like blindness or natural disasters) and moral evil (sin). Both are privations, but of different kinds of goods. A hurricane is a lack of order in nature. A disease is a corruption in the body. A sin, by contrast, is a lack of moral good—of right intention, love, justice, or virtue.

Moral evil, then, is especially significant because it involves a defect in the will. When someone commits an evil act, Aquinas sees that act as lacking something that should be there. If someone hits another person in anger, what’s missing? Tenderness. Patience. Restraint. Love. These are the goods that ought to shape the act but are absent.

“Every evil in the will is a privation of some good that the will ought to have.”
(ST I, Q.48, A.5, ad 1)

So when we say something is morally evil, we’re pointing out that it falls short of what human action is meant to be.

Evil Is Real—But Not a Positive Reality

As I mentioned above, Aquinas is sometimes misunderstood as saying that evil isn’t “real.” That’s not quite right. He’s saying that evil doesn’t have positive being. It’s not a created thing or a force standing opposite to God. Rather, it’s a hole in the fabric of goodness.

“Evil is not found except in good… as in a subject.”
(ST I, Q.48, A.3)

Satan was created good by God. In his essence as a creature, he remains good, but he is profoundly corrupted by the absence of the love and obedience he was created to have. His evil is real, but it is not a substance or nature—it is a privation of the good that should be there. As C.S. Lewis observed somewhere, only very good things can become very bad. You can't make a cow very wicked, but you can make a man terribly so—and an angel worse still. The greater the good, the greater the capacity for corruption when that good is twisted or rejected.

So, again, evil is always parasitic. It needs a host. There’s no such thing as pure evil, because that would mean a being with no goodness at all—and that, Aquinas says, would simply be nothing.

“Since God is the supreme good, He would not allow any evil to exist in His works unless He were so all-powerful and good as to bring good even out of evil.”
(ST I, Q.2, A.3, ad 1)

That’s the final word for Aquinas: God permits evil, not because He approves of it, but because He can draw greater good from it. That doesn’t make evil less painful or less serious—but it does place it within a framework of divine providence. It reminds us that evil, no matter how dark, is not the final word.

Klavan reaches the same conclusion, writing: “Now we see the true idea of moral good is exactly the opposite [of Schopenhauer’s], as St. Augustine said it was. Goodness is the primary original reality and evil is merely ‘the absence of good.’” In recognizing this, Klavan echoes the deeper tradition articulated by Augustine and brought to clarity by Aquinas: evil is not a rival force to good, but a distortion of it. However dark the world may seem, goodness remains the foundation of reality—and that is why evil can never have the final word. “The light shines in the darkness, and the darkness has not overcome it” (John 1:5).