Nature of Evil

Saint Thomas Aquinas and the Nature of Evil

Reality of evil

It is a sad fact of the world that it contains many instances – even a superabundance – of evil: injury, disfigurement, disease, disability, natural disasters: hurricanes, earthquakes, tsunamis, floods, fires, drought. In addition, there are man-made evils: injustice, violence, rape, torture, all manner of cruelty, murder, war, genocide. Disturbing examples of all this evil could be recounted indefinitely, to horrifying effect. In the face of all this pain and misery, it is obviously a challenge to believe that there is an all good, all powerful God who has loving care for his creation.

Indeed, the problem of evil is the major challenge to theistic belief in general, and Christian belief in particular. If anything could definitively prove there is no God, evil is the only reality that might. Indeed, what in philosophy is termed the “problem of evil” is just such an argument which purports to prove that the reality of evil is logically incompatible with the existence of an all-good, all-powerful God.

However, by considering evil in the light of the philosophy of Saint Thomas Aquinas, one can begin to see how evil is at least not incompatible with belief in the God of classical monotheism.

But before we can see how this is so, one should get clear on what evil is, what its nature is; and insights from Saint Thomas Aquinas are extremely helpful for this.

Evil is a privation

First of all, we need to understand that evil is a privation. What does this mean? It is sometimes thought that theists are saying that evil is nothing. This is only sort of right. Evil is not some thing in its own right – like some kind of dark seeping ooze that invades goodness and destroys it.

No, evil is not a “thing” at all, but the falling-short, an emptiness or non-functioning, in something else. As Saint Thomas Aquinas explains, evil is a privation: the lack of being in something good which does exist.

Existing itself chiefly has the nature of being desirable, and so we perceive that everything by nature desires to conserve its existing and avoids things destructive of its existing and resists them as far as possible.  Therefore, existing itself, insofar as it is desirable, is good. . . .  Therefore, evil, which is universally contrary to good, is necessarily also contrary to existing.

Quaestiones Disputatae De Malo 1,1

Aquinas, quite sensibly, claims that evil opposes what is good, and again, quite sensibly understands that what is good is desirable. His insight though is to note that what is most or fundamentally desirable is a thing’s existing – its own being.

So, as a feature opposed to a thing’s good, evil is opposed to that thing’s being – it is a sort of non-being. The non-being that is evil, is not just any and every non-being or absence of good. It is the absence of a due good, the privation of a good that should be there.

Not every absence of good is evil. For absence of good can be taken in a privative and in a negative sense. Absence of good, taken negatively, is not evil; otherwise, it would follow that what does not exist is evil, and also that everything would be evil, through not having the good belonging to something else; for instance, a man would be evil who had not the swiftness of the roe, or the strength of a lion. But the absence of good, taken in a privative sense, is an evil; as, for instance, the privation of sight is called blindness.

Summa Theologiae 1.48.3

So, evil is not just any lack of being. It is the lack of some feature that a thing is supposed to have; it is the lack of a due good. Aquinas gives the classic example of blindness: a lack of an ability to see; but, more specifically, it is a lack of sight in something to which it is due, that is, in the sort of thing which has (or should have) that ability, and so is supposed to see. Unseeing rocks are not called blind, and do not suffer an evil. Only what is supposed to see (and doesn’t) is called blind and suffers an evil.

Aquinas sometimes calls these goods that a thing is supposed to have ‘perfections.’

Now it is clear that a thing is desirable only in so far as it is perfect; for all things desire their own perfection. But everything is perfect so far as it is actual. Therefore it is clear that a thing is perfect so far as it exists.

ST 1.5.1

He doesn’t mean that a thing with some perfection is perfect as God is supposed to be perfect. He is using ‘perfect’ in a more limited way, meaning fulfilled or complete. He is saying a thing is good to the extent that it exists as completely as it should, and it desires its own being and the completeness of being the kind of thing it is. And when there is evil, a thing is lacking a perfection it should have; it is incomplete in its being.

To the extent that a thing falls short of the completeness of its being, to the extent that it lacks a perfection or goodness that it is due, that thing has suffered an evil.

This is important, since it means that evil, because it is a privation of good, cannot exist on its own. It is not a thing in its own right, but describes something that lacks what it is supposed to have. Just as a hole refers to where some material is missing, or a shadow is where a light does not shine, so evil refers to how something is falling short, or is incomplete in what it is supposed be.

Dogs are supposed to run, fetch, chase squirrels; they are supposed to have four limbs, be able to see, hear, smell, etc. A dog that does not have four limbs, that cannot see, etc., for whatever reason, is less than it should be, and so has suffered some evil. Of course, in the case of a dog, or any animal, it is not through their own fault that they have a privation, an evil. This brings up the distinction between natural and moral evil.

Natural vs. Moral evil

Philosophers make a distinction between two kinds of evils according as each kind has a different cause. Aquinas distinguishes them as evil suffered (malum poenae – literally, evil of punishment) and evil done or committed (malum culpae – literally, evil of guilt). Now-a-days, it is common to call these natural or physical evils, on the one hand, and moral evils, on the other. Natural evils occur without any human intervention. One often thinks of earthquakes, hurricanes and tsunamis, but these are natural evil precisely because they bring about the privations of physical goods: injury, disease and death – primarily in humans. Whether they come in large numbers owing to major weather or geological events, or arise spontaneously in individuals: cancers, infectious diseases, birth defects, these natural evils identify what deprives their victims of perfections which should belong to them: bodily integrity, health or life.

The natural evil we know about is all grounded in the destruction of the body of living things. Living things suffer natural evil precisely because they are material, because their nature enlivens matter, and life is a process of acquiring matter to sustain bodies, and shedding or excreting matter so used. Material life is a transitory process. And the matter of any given thing is itself susceptible to becoming the matter for different creatures. Just what it means to be a material living thing is that it has a tenuous and transitory hold on matter which is sought by other material living things. So, material nature just seems to require the good, perfection, and existence of one thing sustaining itself by causing other material things to suffer loss, the privation of their perfection. And of itself, a material thing, by not sustaining itself with the matter of other things, withers, starves and decays, but eventually its matter is incorporated into some other material being.

For Aquinas, moral evil too, (wrong doing, crime, – in a word – sin), is a privation, or lack of a due good, since an action is morally good only insofar as it tends toward the good that is appropriate to human nature as determined by reason.

We must therefore say that every action has goodness, in so far as it has being; whereas it is lacking in goodness, in so far as it is lacking in something that is due to its fullness of being; and thus it is said to be evil: for instance if it lacks the quantity determined by reason, or its due place, or something of the kind.

ST I-II.18.1

So, for Aquinas, even moral evil is a privation of a due good, insofar as human actions ought to follow reason’s judgment about what is the true or appropriate good. Rape or murder is wrong because the victim is owed life or the respect of her body and consent, and the aggressor fails to apply this judgment in his actions.  Furthermore, the moral act has this privation as a result of the free decision; this freedom is what makes the action morally wrong and its perpetrator guilty of a crime. Even when human actions result in a victim suffering a physical or natural evil (in injury or death), what makes the action to be a moral evil is the free choice to deprive the act of the rationality that would make it good.

The ultimate motivation even of moral evil, though, still arises from a desire for some good, but for a lesser good when one is supposed to choose a higher one. Or it arises from the desire for a good that is not appropriate to a given time or place of circumstance. So, for Aquinas (following Aristotle), no one chooses evil as evil; rather one makes an evil choice when one chooses a good which reason should know is lesser or inappropriate instead of the true good. The evil, then, of moral evils depends entirely on the free agent who deprives their own actions of the moral goodness, or rationality, which such acts are due as acts of a rational, human, agent. The free rational agent is solely responsible for the act being deprived of the goodness it should have.

Getting back to natural or physical evil, it may be hard to see how such evils are supposed to be privations. We tend to view the natural evils that tell against God’s goodness as natural disasters, diseases, birth defects and ultimately death. Earthquakes that devastate whole cities and cripple or kill thousands or tens of thousands of innocent people. Virus outbreaks which kill millions or cancers which slowly and painfully take the life of innocent children. The earth or water which move and bury or drown people are real things, not privations; the viruses and cancers which take the lives of their victims are not the lack of something, but biological entities with a kind of life of their own.

These natural evils are not evils and privations in themselves. But they are evil precisely because they bring about non-being or a privation of perfection in those who suffer them: what is evil in these cases is that they cause their victims to suffer a disfunction and to exist as less than they should, even unto the extreme of non-being: death. While the tsunami does exist as a mass of water, its evil consists in the non-being it brings about. A tsunami washing over an uninhabited island is not evil, but is in itself good insofar as it exists. The same with diseases: microbes or cancer tumors are beings, but their evil consists in the disfunction and non-being they cause; indeed, some microbes are good for humans by aiding their being, e.g., in digestion.

To see that evil is a privation is important, first, because it depends on the reality of objective natures. Second, it means that God does not and cannot cause or intend evil.

Evil and Objective Natures

The fact that evil is a privation of a due good implies that whatever things suffer natural or physical evil have objective natures. That is, they exist as belonging to certain classes or categories of things, for, the goodness or perfection that a thing is supposed to have is determined by the kind of thing it is. This is the thing’s nature, the internal principle whereby it is what it is, and does what is characteristic of things of that sort. Dogs, humans and other animals for that matter, have each their own objective nature that is supposed to see; this truth underlies the fact that when they do not see, they have suffered a natural or physical evil.

Aquinas explains that the objective nature of a thing specifies its various perfections, goods which do (or should) belong to it, for it to be complete in its being.

Everything is said to be good so far as it is perfect; for in that way only is it desirable (as shown above (articles 1,3). Now a thing is said to be perfect if it lacks nothing according to the mode of its perfection. But since everything is what it is by its form (and since the form presupposes certain things, and from the form certain things necessarily follow), in order for a thing to be perfect and good it must have a form, together with all that precedes and follows upon that form. . . . But the form itself is signified by the species; for everything is placed in its species by its form. . . . Further, upon the form follows an inclination to the end, or to an action, or something of the sort; for everything, in so far as it is in act, acts and tends towards that which is in accordance with its form.

ST 1.5.5

Since natural or physical evil is real and objective, and since evil is the privation of goodness due to a thing according to its nature, the natures of things have to be real and objective as well, in order for things to suffer these natural evils. Only what has a nature that is supposed to see can suffer the natural evil of being blinded. 

The Problem of Good (or of Natures)

The reality of evil actually gives implicit support for God’s existence and knowledge of his goodness. Since evil is real, and since, as a privation of goods or perfections that are supposed to be present in good things that exist in their own right, the occurrence of real evils actually depends on goodness, goodness which is found in varying degrees of perfections according to the objective natures in things. This all implies there is an all good Creator of good things, who is the objective standard of perfection. Aquinas concludes to the reality of God on this basis in the fourth of his famous Five Ways of proving the existence of God in ST Ia, 2, 3.

God does not cause evil.

Besides implying the reality of objective natures (along with an Author of nature) understanding that evil is a privation or absence of due goodness also shows that evil, as such, is not, and cannot be caused by a good God. An all good God directly causes creatures to exist, and in so doing, causes them to be good as they exist according to the natures he gives them. If evil occurs, it does so by those good things becoming deprived of some goodness or perfection their natures demand.

So, evil is not created at all; it is a lack, and the lack results from good things pursuing their own perfection at the expense of goods of other things. Lions, according to the perfection of their nature, cause the privation of life of gazelles. God causes lions to have the nature they have – he causes their goodness. But permits the evil that that nature entails.

Likewise, God does not cause people to choose sin, but causes the goodness, the existence, of people who are by nature free. They, not God, choose moral evil by failing to act according to the rational demands of their nature, and who freely fail to give others what is due to them according to their nature. God, again, in causing the good of free moral agents does not cause their actions to be deprived of moral goodness; the free agent is completely responsible for that. But God permits the moral evil of some of their free choices.

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