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Aquinas and the Necessity of Natural Evils

The existence of evil is a problem with which every theist in the Western religious tradition must come to grips, but it is especially a problem for the Christian believer who holds that God is not only good and powerful, but all-good and all-powerful. In the attempt to gain a consistent understanding of evil in the light of these divine attributes, theists traditionally distinguish between two main types of evils, moral and natural. The greatest challenge to Christian theism seems to be posed by the existence of natural evils, since moral evils have their origin (at least with respect to their character as evil) in free moral agents. Just as one cannot hold parents at fault for the free evil choices of their children, so one cannot reasonably fault God for the existence of the moral evil caused by his creatures.

Natural evils, however, such as natural disasters or the physical corruption ubiquitously present in all of nature, do seem to be avoidable for an all-powerful God. Moreover, since this God is all-good, it seems that he would want to prevent such natural evils in his creation. The very existence of natural evils seems to indicate that God as all-powerful and all-good does not exist. In a traditional form, the atheological argument posed by the problem of natural evil was presented by Thomas Aquinas in the form of an objection to his proofs for the existence of God in the Summa Theologiae.

It seems that God does not exist; because if one of two contraries be infinite, the other would be altogether destroyed. But the name God means that He is infinite goodness. If, therefore, God existed, there would be no evil discoverable; but there is evil in the world. Therefore God does not exist.1

The Moral Sufficiency of Logical Necessity

Bruce R. Reichenbach seeks to defend God's exists in the face of natural evil by appealing to a morally sufficient reason for the existence of evil.2 According to this view, God must have a morally sufficient reason for allowing natural evils that makes it inappropriate to assign God any blame. Reichenbach accepts the atheist's contention that without a morally sufficient reason one could not reasonably accept the existence of an all-good and all- powerful God. Accordingly, he searches for some fact about the existence of natural evil and God's causality of the natural world which protects God from blame and preserves his perfect goodness.

To claim that natural evils are the unintended consequence of what God does intend, does not ipso facto exonerate God from culpability for their occurrence. Since God is omnipotent, he should be expected to have no limits to what he can bring about. Thus, as omnipotent, he should be able to create a world without natural evils. If such evils do occur, the morally sufficient reason that preserves God's goodness must arise from natural evil being unavoidable. God would be free from blame for natural evils, not only because they are unintended consequences, but more importantly because they are unavoidable.

Only what is logically necessary is unavoidable for God. A state of affairs is logically necessary if the description of the prevention of that state of affairs contains or entails a contradiction. Thus, for example, if God chooses and should choose a given good, and that good logically implies an accompanying evil, God is not blame-worthy for the evil. For God to choose the good but prevent the evil is a contradiction. The occurrence of the evil, in such a case, is logically necessary, and so God cannot be blamed for it. He would still be all-good, even though this evil were present in his creation.

Reichenbach thus proposes a concatenation of unavoidable necessity which renders it inappropriate to blame God for the existence of natural evils. According to Reichenbach, natural evils are the unintended consequence of the world operating according to natural laws, and these natural laws, in turn, are necessary for there to be free moral agents. That God wills free moral agents is likewise necessary because a world without them is inferior to a world with them. Given that God wills to have free moral agents, then he must also will the world to operate according to natural laws, which will result in natural evils. The only alternative to a world operated by natural laws is a world operated by miracle, but such a miraculous world would not allow for the existence of free moral agents and a significant exercise of their freedom. Reichenbach's theodicy thus hangs on this chain of necessity which holds God to having to allow natural evils in order to have free moral agents, which he is also bound to do.

Reichenbach gives two reasons for the impossibility of God creating free moral agents in a world operated my miracle. First, deliberation, a necessary condition for the exercise of rational choice, is prohibited given the confusion and unpredictability of a world operated by miracle. Moral action requires rational deliberation on the best means to attaining one's desired end. However, if the world does not operate according to any regularity, but only according to the caprice of divine will, then a moral agent has no way to anticipate which means are likely to bring about which ends. Moral action is thus thwarted because rational knowledge is impossible.

A second problem with a world in which God miraculously prevents all natural evil is that a rational inhabitant would not be significantly free because he would not have the real ability to do evil. This is because no matter what one intended, no evil results would come from one's actions. Someone who tried to kill his neighbor, for example, would not be free to hurt that neighbor, since God would not allow that neighbor to be hurt. Agents in a miraculous world could do no evil because God would be actively involved in thwarting their attempts to harm each other. Because a morally significant option is not available to such agents, they do not fit Reichenbach's definition of significant freedom. Thus, a world in which God had prevented physical evil would be one without freedom, since evil actions could not be performed. Because it would make freedom impossible, such a world could not have been created by God.

Reichenbach's attempt to float the claim that evil choices are not possible because evil effects are prevented by miraculous intervention arises from his understanding of the nature of moral evil. Moral evil is basically natural evil that is caused by free choice. Thus, presumably, if God eliminates the natural evil effect, then God prevents the evil choice.

Aquinas and the Nature of Natural Evil

Reichenbach's defense of God's goodness in the light of natural evils pays the price of sacrificing his omnipotence. It assumes that God is bound by necessity to create free moral agents, and that this entails the further necessity of natural laws (with incidental evil) in order to have free moral agents. Moreover, these necessities have to be logical necessities: if God did not create free moral agent, and did not run the world by evil- occasioning natural laws, God would be involved in a logical contradiction. Aquinas' approach is different. He is willing to allow God the possibility of having created the world in much different way.

As a general criticism, the kind of evils which Reichenbach's theodicy does explain seem only to be natural disasters, i.e. occasional occurrences of nature wherein various lines of causality incidentally coincide. However, this is a mere subclass of natural evils. Natural evils include not only people and animals being in the wrong place at the wrong time( e.g. when a hurricane is obeying the laws of nature), but also the more pervasive evils of death and disease. A Thomistic theodicy is more comprehensive than Reichenbach's because it takes into account not only natural disasters, but all corruption and death. Aquinas does not consider natural evils to result only from things external to the victim of natural evils obeying natural laws. Rather, for Aquinas, natural evils include natural disasters, but also result from the very nature of things as material.

For Aquinas, bodies by their nature are susceptible to corruption and dissolution. Since they are composed of contrary elements, material things, including humans as bodily, have the potency for corruption.

But since the rational soul is likewise joined to a matter composed of contraries, from the inclination of that matter there results corruptibility in the whole man. In this respect, man is naturally corruptible as regards the nature of his matter, if it is left to its own inclination, but not as regards its form.3

Because it is natural for the human soul to be united to a body composed of various elements, humans have the natural possibility of their bodies dissolving and decomposing. This possibility, however, is not due to their specific nature, i.e. their form or soul; it is due to what is matter for this form, i.e. the body. (For a discussion of the relationship between form and matter see, The Principles of the Philosophy of Nature) However, this possibility would not be actualized were it not due to the action of an exterior agent. The exterior agent, a lion for example, pursuing its own good, nutrition, incidentally bringing about the corruption of another thing, a lamb.

For a natural agent does not intend the privation or corruption; he intends the form to which is yet annexed the privation of some other form, and the generation of one thing, which yet implies the corruption of another.4

The evil of corruption thus is unnatural to material things as regards their form. Nevertheless, the potency to be corrupted arises from their nature as material and composed of contrary elements. The natural evil of death and corruption is incidental to the action of the corrupting agent insofar as it incidentally brings about the corruption of another thing while intending its own preservation.

Given that God wanted to create free moral agents united to material bodies, is he even bound by any necessity that they be subject to the vicissitudes of natural evils? It might be naturally necessary for material things to be corruptible, but since God is the creator of their nature, he, in his omnipotence, need not be bound by their nature. Aquinas says that God's providence, before the Fall of Adam and Eve, could have and would have prevented the corruption that is natural to things, but which is merely potential in them.

Nevertheless, if we look at the matter rightly, it will appear sufficiently probable that, divine providence having fitted each perfection to that which is to be perfected, God has united a higher to a lower nature in order that the former might dominate the latter, and, should any obstacle to this dominion arise through a defect of nature, God by a special and supernatural act of kindness would remove it. Wherefore, since the rational soul is of a higher nature than the body, we believe that it was united to the body under such conditions, that there can be nothing in the body to oppose the soul whereby the body lives.... Hence, according to the teaching of faith, we affirm that man was, from the beginning, so fashioned that as long as his reason was subject to God, not only would his lower powers serve him without hindrance; but there would be nothing in his body to lessen its subjection; since whatever was lacking in nature to bring this about God by His grace would supply.5

Thus, due to his enlightenment by Christian faith, Aquinas believes that man was originally preserved from the potency to corruption, i.e. death, which is implied by his being material, by the miraculous power of God. Such a state is traditionally termed the state of original justice. What is relevant for this philosophical discussion is that an omnipotent God could circumvent the inherent potency to corruption that being composed of contraries implies. Aquinas does see a miraculous world which prevents natural evil, and yet allows that free, moral human agents to be within the power of God to create and sustain.

Aquinas considers this state to be more than merely possible; he thought it was, in fact, probable on theological grounds. However, without this benefit of faith, it is at least possible. Moreover, it seems to be a possibility not considered by Reichenbach. The only alternative he saw to his theodicy was that God should prevent natural evils by direct divine circumvention of natural laws; i.e. a world operated by divine miracle. Is this possible alternate solution Aquinas suggests subject to Reichenbach's criticism of the miraculous world?

The relevant points in which Reichenbach saw the impossibility of combining the divine prevention of natural evil and free moral agents were two, namely that the unpredictability of a miraculous world would prevent the deliberation necessary for moral action, and by preventing the (natural) evil effects of human action, God compromises human freedom by not allowing for evil choices. In order to see if the alternative suggested by Aquinas is really possible, we should see whether it implies unpredictability and a lack of freedom for its inhabitants.

In the first place, it seems that a state in which God supernaturally prevented the potency of corruption inherent in material things from being actualized does not imply that it be chaotic and unpredictable. The miracle that God performs in the state of original justice only preserves the coherence of the human body from the actions of exterior agents which are incidentally destructive. The human body in the state of original justice would be indestructible. As such, it would eliminate all the natural evils with which Reichenbach is concerned, yet natural laws would still operate as they do in our world. Avalanches might still occur, but in order to avoid natural evil, God would not have to make them swerve around climbers or halt at their feet.6 A climber would merely be pelted by snow and suffer no physical harm. The state of original justice would thus be populated by supermen and superwomen made "super-" by the supernatural grace of God. Humans' capacity for ethical deliberation would be unaffected, and if anything improved, because of the complete mastery of the soul over the body which God ensures.

Only if one takes as the definition of moral evil the one given by Reichenbach would the kind of miraculous world suggested by Aquinas prevent significantly free moral behavior by eliminating the possibility of doing evil. Reichenbach defines moral evil as instances of pain and suffering for which human agents are culpable, of which a necessary component is physical or natural evil. But if moral evil consists primarily in an intention, then moral evil is possible and humans in this state of original justice are free. One may not be able to kill one's neighbor or do any physical harm in the state of original justice, but one can fail to give him what is owing to him, e.g. friendship. In an easier case, one is still free because one can in the state of original justice disobey and defy God; such moral evils require no physical evil for their commission.

With Aquinas' understanding of the state of original justice having withstood the critiques of Reichenbach, it seems that God could have created a world without natural evil. It is entirely compatible with the existence of free moral agents, and so God is prevented by no logical necessity from creating it. But on Aquinas' view, neither is he bound positively to create or to continue to sustain it if he had created such a world in the past. Aquinas makes it clear that the state of original justice was sustained by supernatural, gratuitous divine favor. According to Aquinas, no world is so good that God is bound to create it, no so bad that, so long as it has some share of being, he is prevented from creating it. (For an elaboration and justification of this claim, see the article on The Best of All Possible Worlds) God could prevent natural evil, but its occurrence does not imply that God is either not omnipotent or not all-good. The prevention of natural evil is possible for Aquinas precisely because God is omnipotent, but his failure to do so would not entail that God is less than all-good.

P>Thus, Aquinas' reply to the atheological argument, formulated in the first objection to the question of whether there is a God quoted at the beginning of this paper, leaves the reason for evil ultimately as a mystery. "This is part of the infinite goodness of God, that he should allow evil to exist, and out of it produce good."7 The atheological argument from natural evil, however, does not vitiate our assurance in the existence of God. Knowing that God exists and is all-good and all powerful, the existence of evil is a mystery, but it does not undermine this knowledge. If God allows evil, then he must bring good out of it. Yet, God's permission of evil is not necessitated by anything. On the contrary, Aquinas believes that evil did not exist for humans in an Edenic past, and it will be eliminated in a heavenly future. Thus, our assurance in God's goodness and existence, untroubled by the evils present in this world, is based on realities other than, or perhaps deeper than, the mere nature of physical things, vis. the being and goodness of the things in which evil is found.


1 Thomas Aquinas,Summa Theologiae Ia, 2, 3 obj. 1.Return

2 Evil and a Good God, (New York: Fordham University Press, 1982), p. 87Return

3 ST I-II, q. 85, a. 6.Return

4 ST, Ia, q. 19, a. 9.Return

5 Thomas Aquinas, Summa Contra Gentiles, Book IV, ch. 52.Return

6 See Evil and a Good God, p. 108.Return

7 ST Ia, q. 2, a. 3 ad 1.Return

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