Defining Evil: Moral and Natural

Why Definitions Matter

In the last post, we saw that one principle for thinking clearly about evil is to begin with real definitions. If we use vague or sloppy terms, our reasoning will be confused. This is especially true of the word evil. Many people think of evil as if it were some kind of “thing” in itself, like a black substance or a force competing with good. But this way of speaking is misleading. To understand the problem of evil rightly, we must define what it is.

Augustine’s Breakthrough: Evil Is Not a Being

St. Augustine, after years of struggling with Manichean philosophy (which treated good and evil as two opposing substances), discovered the truth: all being is good.

• God is good, and He declared all creation good (Genesis 1).

• Even the devil, considered as a creature, is ontologically good; he exists, and existence itself is good.

• The evil of the devil is not in his being, but in his will.

So what is evil, if not a being? Evil is a privation: a lack of the good that ought to be there. A blind eye is not an evil eye in itself; it is evil because sight, which should be present, is missing. Similarly, a sinful choice is evil because the will lacks its proper order toward God.

This insight is crucial. If evil were a “thing,” then either (1) God created it, in which case He is not all-good, or (2) something else created it, in which case God is not all-powerful. But if evil is a privation, then the goodness of God remains intact, even though creation has gone wrong.

Two Kinds of Evil

With Augustine’s definition in place, we can distinguish between two basic kinds of evil:

1. Moral Evil

This is evil that comes directly from free will: sin, injustice, cruelty, betrayal. Its essence is disordered love. We choose a lesser good (pleasure, power, wealth) over the highest good (God).

• Example: If I kill someone with a sword, the evil is not in the sword—it is in the will that chooses to misuse it.

• Moral evil shows the dignity and danger of freedom. Because we are not machines, our choices matter, and they can be destructive.

  
  

2. Natural Evil

This is evil that does not come directly from free will: disease, disasters, accidents, death. It is still a privation, the absence of health, safety, or life that ought to be present.

• Example: Blindness is evil not because the eye itself is evil, but because it lacks sight.

• Natural evils remind us that creation itself shares in the wound of sin. After the Fall, humanity and nature are not in harmony. As Genesis says, “thorns and thistles” mark the ground, and as St. Paul adds, “the whole creation has been groaning” (Rom 8:22).

Why the Distinction Matters

If we confuse moral and natural evil, we risk blaming God for what is our fault or blaming ourselves for what is beyond our control. Recognizing the difference helps us to see both the seriousness of sin and the mystery of suffering.

But they are not unrelated. Christian teaching holds that natural evil is ultimately connected to moral evil through the Fall. We were made as a unity of body and soul, and when our souls turned away from God, our bodies and the world around us became subject to corruption and death. Spiritual alienation leads to physical suffering.

This does not mean every sickness or disaster is caused by a specific sin. Rather, it means that sin and suffering are bound together in the brokenness of creation.

The Path Forward

By defining evil carefully, we clear away much confusion. Evil is not a “thing.” It is a lack of the good that ought to be. It comes in two forms: moral (sin) and natural (suffering). Both are real, both are serious, and both cry out for redemption.

In the next post, we will explore how free will plays a central role in understanding moral evil, and why God gave us freedom even though it makes sin possible. That insight is essential if we are to see how God’s goodness and power are not contradicted by the existence of evil.