Problem of Evil

Saint Thomas Aquinas and the Problem 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.

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.

Atheistic argument

The problem of evil is presented philosophically as an argument against the existence of the God of classical monotheism:

  1. If God is all-good, he would want to eliminate all evil.
  2. If God is all-powerful, he can do anything he wants; so, he would be able to eliminate all evil.
  3. Therefore, if God existed, there would be no evil.
  4. But there is evil.

Therefore, an all good, all powerful God does not exist.

As it is given here, this argument is valid. The question is whether the premises are true and so, whether the conclusion really follows. Obviously, theists admit that premise 4 is true: evil is a sad fact of the world. So, to determine whether one should conclude that there is no such God, one has to determine whether the other two premises are true. To do so, we need to understand what evil is, but also what we mean by saying that God is all-good and all-powerful.

Evil is a privation

Elsewhere I examine what Aquinas means when he says that evil is a privation.  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. It is the lack of being or perfection in something good which does exist.

Thus, evil is not created; 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, but permits the evil that that nature entails.

Likewise, God does not cause people to choose sin, but causes people who are by nature free to exist; they, not God, choose to sin by failing to act according to the rational demands of their nature, and they 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.

God’s Power and the Occurrence of Evil

But, even if it is granted that God does not directly cause natural or moral evil, some object that if he were all good and all-powerful, he could and would nevertheless prevent all evil. But is this true? Could an all good God prevent all evil?

An obvious, if facile, answer is: Sure, if he did not create anything at all, there would be no opportunity for any privation of good to occur. But that is not very interesting, and it does not address the evil that we see does in fact occur. Rather, the atheist claim really is that if God is all-good and all-powerful, he could create the good of our world without the occurrence of any evil.

Thomas Aquinas takes up this question in Summa Theologiae Part 1, Question 22, Article 2 when he asks “Whether everything is subject to the providence of God?” As an objection to his position, he writes:

Objection 2: Further, a wise provider excludes any defect or evil, as far as he can, from those over whom he has a care. But we see many evils existing. Either, then, God cannot hinder these, and thus is not omnipotent; or else He does not have care for everything.

Aquinas, however, shows that given what we know about the nature of material living things and of free moral agents, God could not prevent all natural and moral evil, without sacrificing greater good, and moreover, there is good reason to think that, in his goodness, God would not want to do this.

To see why, one has to consider what God can do, and whether there is any limit to what an all-powerful God is able to do. For Aquinas, the only thing that God cannot cause is what cannot exist, that is, what is logically impossible.

Part of the reason theists, or at least Christians, claim that God is all-powerful is precisely because he is believed to do impossible things, such as raise the dead, walk on water, or turn water into wine. But in all of these miraculous cases, what is impossible is that things act in a particular instance in a way that is contrary to how we understand they normally act, but not in ways that are contradictory in themselves (See ST I.105.6). Water does not normally turn into wine, but when it is wine, it is not still water. Wine cannot be both wine and water (not-wine) at the same time (and in the same respect).

Aquinas, however, argues that even God cannot cause what is logically contradictory, not because God lacks some ability to act, but because such contradictory “things” are not, and cannot be, things at all; such “things” cannot exist.

Now nothing is opposed to the idea of being except non-being. Therefore, that which implies being and non-being at the same time is repugnant to the idea of an absolutely possible thing, within the scope of the divine omnipotence. For such cannot come under the divine omnipotence, not because of any defect in the power of God, but because it has not the nature of a feasible or possible thing. Therefore, everything that does not imply a contradiction in terms, is numbered amongst those possible things, in respect of which God is called omnipotent: whereas whatever implies contradiction does not come within the scope of divine omnipotence, because it cannot have the aspect of possibility. Hence it is better to say that such things cannot be done, than that God cannot do them.

ST 1.25.3

A famous example is the “rock too great for God to move”, but there is also the “married bachelor” or “round circle.” Such things contain a contradiction in their description, and so would have both to be and not be at the same time and in the same respect. The famed immovable rock would have to be simultaneously both subject to and not subject to a creator God; a married bachelor would have to simultaneously both have and not have a wife, and so on. Once one sees this trick of describing things with contradictory attributes, one can extend the list of “things” God cannot make or do: God cannot make a one-ended stick or a bigger half; God cannot create another God (see ST 1.7.2 reply to objection 1) or commit suicide.

So, is it possible for God to create something which did not suffer natural evil? 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.

Could God create things immune to this kind of natural evil? Well, if there were or could be things without bodies, they might be immune from the harm or destruction of losing matter, but we couldn’t possibly know whether they might somehow suffer some other kind of injury, since our whole understanding of injury or harm depends on the presence of bodies.

But the material things we do know about are good, yet, for there to be material things that were naturally not susceptible to suffering harm or death would be logically impossible.

As Aquinas says in replying to the objection raised before:

Corruption and defects in natural things are said to be contrary to some particular nature; yet they are in keeping with the plan of universal nature; inasmuch as the defect in one thing yields to the good of another, or even to the universal good: for the corruption of one is the generation of another, and through this it is that a species is kept in existence. Since God, then, provides universally for all being, it belongs to His providence to permit certain defects in particular effects, that the perfect good of the universe may not be hindered, for if all evil were prevented, much good would be absent from the universe. A lion would cease to live, if there were no slaying of animals.

ST 1.22.2 Reply Obj. 2

Predators who ate no prey would be a contradiction, and living, material things which did not need to assimilate the matter of other things (eat) and which could not have their matter assimilated by other things (die) would be as contradictory as a married bachelor.

Of course, death and natural evil were not originally part of God’s plan for humans, according to Christians; human death itself is a consequence of moral evil. Aquinas, as a Christian, believed that the first human parents lived in the garden of Eden in an original harmony with God; they were immortal and not subject to harm or decay, but God bestowed this immortality by a special, miraculous favor, not by changing the nature of material being.

Given what know about life on earth, we can see further how this truth plays out. The water cycle and weather patterns which makes life itself possible also gives rise to hurricanes, flooding and even earthquakes. The tendencies of genes to mutate gave rise to great diversity of life through evolution, but also gives rise to cancers. Such natural goods and the greater good of a universal order to nature are impossible without concomitant natural evils. This is a harsh reality of the world, but does not indicate it was not created by an all-good God, constrained by material nature. If a better world was possible, it does not take away the goodness of the material world that is.

Free Will, Morality and Evil

So, given that natural evil accompanies material natures, Aquinas goes further in noting that there are even greater moral goods that are impossible without natural and moral evil. Continuing from the text from before:

If all evil were prevented, much good would be absent from the universe. . . . there would be no patience of martyrs if there were no tyrannical persecution. Thus Augustine says (Enchiridion 2): “Almighty God would in no wise permit evil to exist in His works, unless He were so almighty and so good as to produce good even from evil.”

ST 1.22.2 Reply OBJ 2

Not only does is the universal order and harmony of nature impossible without natural evil, moral goods are impossible without permitting both natural and moral evil.

First, a world populated with indestructible physical beings severely limits morally significant choices. If human cannot suffer death or any physical harm, they cannot obey or disobey a command not to kill, nor to care for vulnerable children, the injured or the aged. Just as an injunction against psychic assault or non-consensual mind probes in our world is obviated by limitations of our mental abilities, so without the possibility of natural evil, most morally significant actions would likewise not be possible. Our material world is just what makes possible the greater moral goods of compassionate care, moderation and justice, and these moral goods outweigh the natural evils on which they depend.

Again, God could prevent moral evil by not creating free moral agents. Without free moral agents there would be no moral evil, but then there would be no morally good choices to love and care for those who need our care, either. There is a great good in creating free agents since only such free agents are capable of love.

But, could God create free moral agents and yet prevent them from making morally evil choices? For Aquinas, God is the cause of all actuality in the world, but he causes agents to act according to the nature he gave them. So, he causes free agents to act freely.  And as we noted in the essay on the nature of evil as a privation, God causes all that is good and perfect in a free creature’s free act. If there is any defect or privation in a free act, the free creature is the cause of such moral evil by freely pursuing a lesser or inappropriate good and depriving his action of the rationality, the goodness or perfection with which he is supposed to act.

Famously, Aquinas notes that it is possible that God could grant a special grace whereby the agent freely did not fail in knowing the true good or in freely choosing to pursue it. So, technically it is not logically impossible for him to create free agents and yet prevent moral evil. It should be noted, though, that God would have no moral obligation to give the grace which would so prevent such evil.

Thus, in willing free creatures, Aquinas believes, it is not strictly logically necessary that God must allow for there to be moral evil; Aquinas, thus, would not accept the so-called Free Will Defense. But if God does not prevent such moral evil, Aquinas, following Augustine, says it is because this moral evil is conditionally necessary in order for him to draw greater good from it.

For, some specific moral goods are logically impossible without accompanying evils, and even an all-powerful God cannot do what is logically impossible. There could be no compassion, curing or comfort without the existence of pain, suffering, disease, and death. There can be no patience, courage, or heroic sacrifice without hardship, danger, pain and death to struggle against, and sometimes these natural evils are caused by free agents who choose moral evil.

And at an even higher level, some even greater moral goods are impossible without moral evils. There can be no repentance, forgiveness or redemption without moral failures to repent of, to forgive, or to redeem. It is rare to see on a human level, but relationships can achieve greater goodness and beauty when one party forgives and heals a betrayal, a goodness and beauty not possible had there not been the betrayal. While not a necessary conclusion of this line of reasoning, it opens the possibility for Christians to see even the Fall of Adam and Eve as the Felix Culpa, the Happy Fault which was the occasion for God to redeem sin and suffering through the voluntary sacrifice of His Son in Jesus Christ.

God then does not cause the evil in the world, natural or moral. But he does permit it, in that he creates the good things in the world which suffer natural evil or commit moral evil. With the evil occurring or being a part of the world, it provides the necessary conditions for greater goods to be drawn from them, goods logically impossible without them.

So, given what we know about the nature of evil and God’s omnipotence we can revise the argument against God’s existence from evil from the beginning of this discussion:

The original argument stated:

1. If God is all-good, he would want to eliminate all evil.

Upon reflection, the truth is:
1’. If God is all-good, he would want to maximize good.

The original argument also stated:

2. If God is all-powerful, he can do anything he wants;
    he would be able to eliminate all evil.

Upon reflection, the truth is:
2’. If God is all-powerful, he cannot eliminate the evil
that is logically necessary for greater goods, but
permits necessary evil and draws greater good from it.

The original argument concluded:

3. Therefore, if God existed, there would be no evil.

Upon reflection, the truth is:
3’. Therefore, if God exists, there should be evils
necessary for greater goods.

Again, accepting reality, we can all admit:

4. But there is evil.

Finally, the original argument came to the conclusion:

Therefore, an all good, all powerful God does not exist.

Upon reflection, the truth is:
Therefore, an all-good, all-powerful God is
not impossible given there is evil.

Some Qualifications

One should note the limit of this theodicy. Neither I, nor Aquinas, am saying that God causes natural or moral evil as means in order to bring about greater goods. A god who did that has rightly been likened to a cruel schoolmaster or mad scientists who makes subjects better by torturing them. Here, the sadist is the cause of the evil, and while good may result, the sadist has no right to inflict it.

However, since evil is a privation of goodness, it cannot be caused by an all-good God, the First Cause of Being. But since evils do occur given the world he has created (even if he foreknows them), it is not irrational to believe that God allows such evil, and uses it to bring about goods that far outweigh them.

Moreover, at most we can see that this explanation is cogent only at a very high level of generality. We might accept that earthquakes, tornados and hurricanes are just part of nature, or that disease, death and decay are just a part of life. We might even accept that much good, natural and moral, comes from them. But when a father sees his wife and child swept away in flood waters, or a mother watches her young son painfully waste away and die of cancer, however true it is, the general theory about the necessity of natural evil will nevertheless seem weak, vain and perhaps itself cruel. Likewise, perhaps much good has come from cruelty and injustice throughout human history, but if we ourselves have been the victim of a cruel injustice, to suppose that it is an occasion to right future wrongs or to forgive our enemies could seem absurd. We can accept that good results are possible in the abstract, and even that it actually happens in particular cases, but to one in the midst of physical and moral evil, the general reasoning will often seem vain and hollow. But, still, general conclusions can be true, even if they do not seem so when one is suffering, and the general theodicy can and does help victims of tragedy cope with the pain of evil, and maintain belief in an all good, all-powerful God.

Finally, as presented here so far, these observations only go to overcome the argument that evil is incompatible with an all-good, all-powerful God. They only show that it is not impossible that God exists given the evil in the world. It does not prove that God exists, nor that God actually does bring greater good from all the evil there actually is.

This then opens up the atheists’ counter argument:

  1. God would allow only the evil that actually produces greater good. He would not allow any unredeemed or pointless suffering.
  2. But we do see pointless suffering.
  3. Therefore, there is (probably) no God.

Big picture

To this counter argument, the theist can only reply by denying the second premise: while it may seem that there is pointless suffering, it must be the case that there is none. All suffering must be redeemed by being necessary for some greater good. And the reasons for this, while perhaps unpersuasive for the atheist, are the nevertheless, true:

1. God exists, and there are good reasons to accept that he exists and that he is both all-good and all-powerful.

2. Our view of the interrelations among the goods and evils we experience, both theist and atheist would have to admit, are all rather limited. It has to be at least possible that there is a Big Picture wherein all evil is necessary, and, if so, we would see only a very small part of it. But in this small part we know that some evil is necessary, and, while some evil seems to be senseless, it is likewise possible that even this seemingly senseless evil, too, is necessary when viewed from a perspective unavailable to us finite creatures.

3. Since there is good reason to believe that there is a God who is not only all-good and all-powerful, but all-knowing as well, there is good reason to believe that there is this Big Picture, and that all the evil in the world is necessary for greater goods, and for an overall, universal greatest good.

Fyodor Dostoyevsky in a celebrated passage from the Brothers Karamazov explores this Big Picture in vivid, heartbreaking detail, which culminates with the seemingly most senseless evil of a small child being thrown to hunting dogs and torn to pieces before his anguished mother. The character of the atheist brother, Ivan, rails against the absurdity of supposing there could be a universal harmony that renders such evils not senseless, but necessary and redeemed. Such a Big Picture is supremely absurd, unless there were in all the world a being that has both the ability and the right to forgive these evils which even these child victims and their aggrieved mothers would not have. Only in light of such a being could there actually be any Big Picture which precludes senseless evil.

The young novice monk character, Alyosha, as a Christian, retorts that there is such a being both able and entitled to forgive and redeem all the apparently senseless evil, since he is its victim most of all. He is referring, of course, to God himself, made incarnate in Jesus Christ. From God’s perspective, says the Christian, no evil is senseless, all is necessary and redeemed.

Ivan’s response is to relate his ‘poem’ of the Grand Inquisitor. It is too much to explore the portrait of Jesus which Dostoyevsky gives us in this ‘poem’, but in general terms it is of a God who so totally loves and respects human being, infinitely more than they do themselves, far beyond any human capacity to love.  This God of ultimate, unconditional love even embraces the Grand Inquisitor himself who fully and finally betrays that love. Only such a God is sufficient to completely resolve the problem of evil, and this declaration is perhaps the most shocking and audacious claim a Christian can make.

And not all can accept it; Ivan the atheist cannot: it demands a price too high for him to pay, and he wishes merely to return his ticket to existence.

It is too big a topic to explore any further here. Elsewhere, we can look at how Aquinas understood how Jesus redeems evil through his death on the cross, especially the evil of the sins of each of us. Faith in the power of such love is, in the end, the only thing that can approach a full answer to the problem of evil.


The philosophy of Saint Thomas Aquinas gives some insight into how the existence of evil does not prove that an all-good, all-powerful God is impossible. From the fact that evil is a privation, and that even an all-powerful God cannot bring about effects that are logical contradictions, God allows the evils necessary for the greater goods he positively desires. As hard as it is to see or accept, all the evil in the world must be necessary when seen from God’s perspective, and for the Christian, in the death and resurrection of Jesus Christ, all this evil is redeemed, and God’s good creation will ultimately be restored and more.

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