The Problem of Evil
Of all the objections to theism presented by atheists, the most celebrated and oft-rehearsed, by far, is the problem of evil and suffering. Debates about evolution and the like notwithstanding, most reflective theists would likely agree that objections to belief in God posed by the occurrence of evil and suffering present a far more serious challenge than do objections from science. (In fact, one of the most popular lines of objection to theistic evolution is really a version of the problem of evil; it asks, How could a perfectly loving God employ a means of creation that proceeds by way of the systematic destruction of the weakest and most vulnerable creatures?) A distinction must be drawn, however, between the problem of evil as a philosophical objection to religious belief and the problem as a concerned question.
Some philosophers have put forward arguments from evil which purport to show that God does not exist or that belief in God is unreasonable. To such philosophical attacks, philosophical responses are appropriate. However, many people—believers and nonbelievers alike—are bothered by evil. When they are faced with suffering, on their own part or on the part of others, they may pose an agonizing Why? A philosophical argument is often the last thing such a person wants to hear; such an argument may appear irritatingly superficial or even callous. The person wants compassion and empathy, and the proper response may simply be to listen and try to share the other’s grief and questions. At such times the problem of evil calls more for pastoral care than for philosophical debate.
The philosophical problem of evil, on the other hand, can be posed briefly and sharply. It appears to many people that a perfectly good, all-knowing and all-powerful being, were he to exist, would not allow the kinds or quantity of evil and suffering that exists in our world. The underlying assumption of this argument is the intuition—common to many atheists and theists alike—that a good being eliminates evil as far as it is able to. God, being omniscient, should be aware of every instance of evil and suffering; being perfectly good, he would presumably want to eliminate all evil; being omnipotent, he should be able to do just that. If there were a God, therefore, one would expect not to find any evil in the world. Since one does find evil—and quite a bit of it—God must not exist. In this way, the existence of evil and suffering is thought to undermine the rationality of belief in God.
Types of Evil, Versions of the Problem and Types of Responses
The evils in the world which this argument takes as its basis are usually divided into two types. Moral evil is all the evil which is due to the actions of free, morally responsible beings. Murders, rapes and the hunger caused by social injustice would be examples of moral evil. Natural evil (or nonmoral evil) is all the evil that is not (or at least does not appear to be) due to the actions of morally responsible beings, such as the pain and suffering caused by natural disasters and many diseases. It might seem strange to call pain and suffering a kind of “evil”—many people are accustomed to using the term only to refer to moral evil—but we should not be tripped up by this terminological usage. The reason for the label becomes clear when we consider that pain and suffering of any kind seem—at face value—out of place in a world governed by an all-powerful, all-knowing, and perfectly good and loving God. The problem of evil thus extends to pain and suffering of any kind, including that resulting from “natural” causes.
A distinction must also be made between two types of arguments from evil. Some philosophers believe that the existence of evil constitutes a proof that God does not exist. On their view the occurrence of evil and the existence of God are logically incompatible: it is a contradiction to claim both that a perfectly good, all-knowing, all-powerful being exists and that evil exists. This is called the logical form of the problem of evil.
Other atheistic philosophers make a more modest claim. They are willing to admit that God’s existence is logically compatible with the occurrence of evil: they concede that it is possible that a perfectly good, all-knowing, all-powerful being might have reasons for allowing evil. However, they allege that, given the actual types and quantity of evil that we find in the world, it is unlikely or improbable that this is so in every case. Hence, the occurrence of evil, though it does not prove that God does not exist, renders his existence unlikely or improbable. This line of argument is called the evidential form of the problem of evil. We will address each of these versions of the problem in turn.
Theistic responses to the problem of evil can also be divided into two types. The more ambitious type of response is a theodicy, which attempts to explain why God actually allows evil. A theodicy tries to show that God is justified in allowing evil; it lays out the reasons why God allows evil and tries to show that those reasons are good ones. A more modest type of response, called a defense, tries to argue that God may have reasons for allowing evil that we do not or cannot know. A defense does not try to explain why God actually allows evil but argues that it is reasonable to believe that God has good reasons, even if we are not in a position to discern what they are. A defense may give various explanations as possible reasons why God allows evil, but without claiming that those reasons are necessarily God’s actual ones.
There are certain ways of resolving the problem of evil that, while perhaps logically adequate, are not genuine options for the orthodox theist.  One way is simply to deny the reality of evil, to view evil as an illusion. This view—aside from the difficulty that it must still face the problem of the evil of a widespread, illusory belief—is simply not consistent with Christianity, Judaism and Islam, which take evil as something which is all too real and which must be treated with great seriousness.
Another way of resolving the problem would be to regard God as limited in either power or knowledge or goodness or all three. Perhaps evil is due to a recalcitrant material that God is doing his best to straighten out, or perhaps some recalcitrant streak in God’s own character that he is still trying to tame. The former option was urged by the school of Boston Personalism in the early twentieth century, while both have been asserted by various process theologians. Such “finite theisms” are perhaps worthy of consideration, but it is clear that any such position represents a major modification of traditional theism, and, as such, an abandonment of essential elements of the great theistic religions. Before accepting some such view, it is wise to see whether orthodox theism has within it the resources to solve the problem of evil.
The Logical Form of the Problem
One of the most well-known statements of the logical form of the problem of evil comes from J. L. Mackie, who claims that it is “positively irrational” to affirm, on the one hand, that God exists and is wholly goodand omnipotent, and yet to admit, on the other, that evil exists.  Mackie admits that the contradiction is not immediately obvious; to show it, he says, some additional premises must be added which spell out the meaning of terms like “good,” “evil” and “omnipotent.”
These additional principles are that good is opposed to evil, in such a way that a good thing always eliminates evil as far as it can, and that there are no limits to what an omnipotent thing can do. From these it follows that a good omnipotent thing eliminates evil completely, and then the propositionsthat a good omnipotent thing exists and that evil exists are incompatible. 
Mackie is claiming that the proposition that God exists, combined with his additional premises, logically implies that evil does not exist, which contradicts the (obviously true) proposition that evil does exist.
Theistic responses to Mackie’s argument (and to other similar arguments) have typically focused on the claim that a good being always eliminates evil as far as it can. Why should we accept this additional premise? There seem to be quite a few circumstances in which a good being allows evil to occur which could be eliminated, for the reason that eliminating the evil would also eliminate a good which is great enough to “outweigh” the evil allowed. For example, a heroic soldier might fall on a live grenade to save his comrades. His death is surely an evil (in the sense that we are using this term), yet his action in bringing about this evil is nonetheless the action of a good person. Perhaps by diving into a trench, the soldier could save his own life and prevent that evil, but to do so would result in a greater evil (the death of all his comrades). So the good that is brought about by his action outweighs the evil.
It does not seem to be true, then, that a good being always eliminates evil as far as it can. What is true, perhaps, is that a good being always eliminates evil as far as it can without the loss of a greater good or the allowance of a worse evil. Almost all contemporary theodicies base their arguments on this type of “greater-good” principle. The evil that God permits is justified because allowing that evil makes possible the achievement of a greater good or the prevention of a worse evil.
But at this point we must be careful how we employ the “greater-good” relation in dealing with the problem of evil. The critic is likely to object that an omnipotent being must be able to eliminate evil completely, without any net loss of good or increase of evil, for, unlike our heroic soldier, an omnipotent being is supposed to be able to do anything. God, if truly omnipotent, would never find himself in a position in which some good is “out of reach” unless he allows some evil to occur. He could never find himself in a position analogous to the heroic soldier, for example, because he could always bring about the good result directly (e.g., by causing the grenade not to explode or by causing the soldiers to be miraculously unharmed in the blast). The “greater-good” principle thus applies only to beings of limited power, like ourselves.
The response to this has traditionally been that not even an omnipotent being can do literally anything. One limitation on omnipotence which has generally been accepted by theists, as we noted in chapter two, is that even God cannot do what is broadly logically impossible. An omnipotent being cannot create a square circle or bring it about that 2 + 2 = 5, because these contradictory states of affairs are not genuine possibilities.
Whether this point is of any relevance to the present discussion, however, depends on whether the allowance of certain evils is logically necessaryfor certain goods to be achieved. But it seems plausible that this is so. Let us define a second-order good as a good that logically requires the existence (or at least the possibility) of some evil in order to be realized. Various kinds of goods and evils have been claimed to be related in this way, giving rise to various types of theodicies. For example, certain kinds of moral virtues seem to logically require certain evils. Courage seems inconceivable without the possibility of harm. Sympathy would be impossible apart from the suffering of others. Perhaps much of the evil in the world—particularly much of the natural evil—is necessary for human beings to have the opportunity to cultivate the moral virtues, which are second-order goods. Perhaps, furthermore, these second-order goods are of such great value that their realization justifies the allowance of the evils whose existence (or possibility) they require. The idea certainly does not seem far-fetched, and it can be developed into a theodicy: the world has been designed by God to be, first and foremost, an environment that enables and facilitates each individual’s moral and spiritual development. This solution is termed a soul-making theodicy. 
The difficulties with soul-making theodicies are plentiful. One problem is that not all natural evils seem to contribute to any greater good—the suffering of some animals, for example. Consider a scenario in which, far away from any human witness, a lightning strike starts a forest fire that burnsa fawn severely and causes it to experience a slow, agonizing death.  Surely events like this occur, but why would a loving God allow them? There appears to be no second-order good for which this evil is necessary. A second problem is that—in addition to making possible various second-order goods, such as courage and sympathy—evils such as pain and suffering also make possible second-order evils, such as cowardice and maliciousness. Allowing such evils as pain and suffering does not, then, always lead to a greater good, and it even opens the door for certain evils that otherwise would be impossible. Or, to put the point differently, if second-order goods suffice to justify “first-order” evils like pain and suffering, the problem of evil simply switches its focus to the existence of second-order evils, such as cowardice and maliciousness. By itself, the soul-making theodicy seems unable to identify any greater good that could justify God’s allowance of these second-order evils. 
Because of this last problem, most theists who advocate a soul-making theodicy incorporate into their view another kind of theodicy as well: the free will theodicy. According to this solution, the reason that second-order evils occur, such as acts of cowardice and maliciousness, is that human beings make bad use of their freedom. The resulting evil is due to human wickedness, not to God.
But why should God give humans free will, and why should he allow them to use it so badly? The traditional answer is that moral freedom is a great good which outweighs the possibility of evil that its existence requires. More specifically, God allows humans to act freely because, without doing so, humans could not be morally responsible agents, capable of freely doing good by responding to and loving their neighbors and their Creator. In creating human beings, God desired to make creatures who would freely love and serve him. The “love” of a robot who can do nothing else is not worth much. The highest expression of love is communion with God, the greatest possible good for a human being. But for God to leave us genuinely free to act is for him to allow us the possibility of misusing that freedom—allowing us, for example, to choose to perform acts of great cowardice or maliciousness. True freedom thus involves great risk, but also the possibility of a great good which can be achieved in no other way. In this manner the soul-making theodicy and free will theodicy work together to account for both first-order and second-order evil.
But why—the critic might ask—couldn’t God give humans free will and guarantee that they always use their freedom wisely? Upon first encounter the critic’s question strikes many as nonsensical: surely, it is thought, if humans are genuinely free, then sometimes they will put that freedom to bad use. If God had created a world in which it was guaranteed that no one would ever do anything wrong, then the “freedom” of his creatures would not have been real; it would have been some kind of pseudofreedom.
But before we dismiss the critic too quickly, we should consider the way that Mackie formulates the objection:
I should ask this: if God has made men such that in their free choices they sometimes prefer what is good and sometimes what is evil, why could he not have made men such that they always freely choose the good? If there is no logical impossibility in a man’s freely choosing the good on one, or on several, occasions, there cannot be a logical impossibility in his freely choosing the good on every occasion. God was not, then, faced with a choice between making innocent automata and making beings who, in acting freely, would sometimes go wrong: there was open to him the obviously better possibility of making beings who would act freely but always go right. Clearly, his failure to avail himself ofthis possibility is inconsistent with his being both omnipotent and wholly good. 
What Mackie’s objection highlights is this: a scenario in which God creates free creatures who always freely choose to do what is right does seem to be a logically possible state of affairs and thus a component of a logically possible “world,” a maximal possible way things could have been. But if God is omnipotent, then it has usually been thought that he can bring about anything that is logically possible: omnipotence implies that God can actualize any possible world. It seems to follow that it was within God’s power to create a world containing free creatures but no evil. Thus the presence of evil in the world, if this line of thinking is correct, entails that an omnipotent, perfectly good God does not exist.
However, Alvin Plantinga has developed a powerful argument that Mackie’s objection is not sound. The heart of Plantinga’s argument rests on the libertarian view of freedom, which implies that if a person has a genuinely free choice, what the person will do in that situation is solely up to the person and not up to God. Suppose some individual is faced with a choice as to whether he will perform some immoral act, such as accepting a bribe. On Plantinga’s (fictional) example, a politician named Curley has accepted a bribe of $35,000.  That is, in the imagined world it is true that Curley has actually accepted the bribe. Suppose, however, Curley had been offered a lesser sum, say only $20,000. Would he have accepted this lesser bribe? Many philosophers would agree that one of the following propositions (but not both) is true:
1. If Curley had been offered $20,000, he would have accepted the bribe.
2. If Curley had been offered $20,000, he would have rejected the bribe.
Notice that both propositions (1) and (2) seem logically possible, and thus there is a possible world in which Curley accepts the lesser bribe and also a possible world in which he rejects the lesser bribe. Suppose that (1) is true: Curley would freely accept the lesser bribe if it were offered. In that case, there is a logically possible world that God cannot actualize: namely, the one in which (2) is true and Curley rejects the bribe. If, on the other hand, (2) is true and Curley would freely reject the bribe, then the possible world in which proposition (1) is true turns out to be the world that God cannot actualize. Either way, it turns out that if we assume libertarian free will, and we assume that either proposition (1) or (2) must be true, then there arelogically possible worlds which even an omnipotent being cannot bring into existence. 
This conclusion directly undermines Mackie’s objection, which rests on the assumption that there is a logically possible world in which free beings exist but never do evil. Plantinga’s response is to concede that there is such a logically possible world, but to claim that we have no reason to think that this world is one that is within God’s power to create. There are some logically possible worlds God cannot create; whether God can create a particular world depends on the choices made by the free creatures in it.
Perhaps Mackie might respond at this point by claiming that God, making use of his “middle knowledge” about what free creatures will do in various situations, should only have actualized free creatures who would never do evil. However, even if God does possess middle knowledge (and we saw earlier that there may be problems with such a view), how do we know that there are possible free creatures who, if God created them, would never misuse their freedom? It seems at least possible that all the free beings God could actualize would misuse their freedom at some time. (Plantinga calls this condition “transworld depravity,” since a creature with this condition willdo some evil in any possible world in which that creature exists.) 
The upshot is this. It seems clearly possible that God could have faced this scenario in which all the creatures he could create have transworld depravity, and if he had faced it, then any world he actualized containing free creatures would also (eventually) have contained evil. On the assumption that a world with both free creatures and evil is better than a world with neither, God was justified in creating free creatures, even though he knew full well that in doing so the result would be (eventually) a “fallen” world.
What this scenario shows is that God and evil are logically compatible. Note that Plantinga is not claiming that God in fact faced this scenario. He is claiming only that it is possible that God faced it. This is all Plantinga needs, because Mackie has asserted that God and evil are logically incompatible—in other words, that there is no possible way that the world could have been such that God and evil both exist. Plantinga’s argument is a free will defense: it does not state what God’s actual reasons are for allowing evil but only what they could be. God’s actual reasons for allowing evil may be ones that we do not know and perhaps could not know.
It should be noted that difficulties for a free will theodicy(which is more ambitious than a free will defense) remain. Obviously, such a theodicy is no more valid than the underlying theory of free will it embodies, and, as we have encountered on more than one occasion, the debate between compatibilists and incompatibilists is ongoing, and it is one that we cannot hope to resolve here.  Another difficulty is that, as we have developed it so far, a free will theodicy by itself appears to account only for moral evil. To account for natural evil, the free will argument must be extended in one of three ways. One way is to combine it with another theodicy, such as a soul-making theodicy, which accounts for natural evil. Recall, however, that this combination still faced difficulties in accounting for certain kinds of natural evil: namely, those that seem to bear no relation to human free will (such as animal suffering). A second way would be to see natural evil as the work of superhuman free beings, such as Satan and his angels; this thinking converts natural evil into moral evil. A third possibility would be to see natural evil as in some way a consequence of moral evil, perhaps by interpreting it as a divine judgment on a fallen race. There is biblical support for the idea that the current state of nature is “unnatural,” in the sense that it is a consequence of sin, not an expression of God’s original plan or intention for it (see Gen 3:17-19; Rom 8:19-23).
Regardless of which option one selects, critics of theism will question one’s basis for claiming to know that natural evil should be viewed in that way. It must be admitted that, as full-fledged theodicies, neither free will arguments alone nor such arguments taken in conjunction with a soul-making argument can be established conclusively. When all is said and done, it is difficult for the theist to be confident that she truly understands why God allows all the evil we find in the world.
Fortunately for the theist, though, it is not necessary to have a full-fledged theodicy to rebut the logical form of the problem of evil. For the charge of the atheist, in this case, is that theism is self-contradictory. To rebut this charge, it is not necessary to know God’s actual reasons for allowing evil or to be able to explain why God allows the evils he does. It is sufficient to know that there are possible reasons why an all-good, omnipotent being might allow evil, if one wishes to show that the occurrence of evil and the existence of God are not logically contradictory. (It is for this reason that Plantinga’s response to Mackie is a free will defense and not a free will theodicy.)
As theodicies, the soul-making and free will arguments may have their limitations, but their value in producing a defense against the logical form of the problem of evil is formidable. The free will argument, for example, shows that it is not necessarily true that a good being always eliminates all the evil it can, or that an omnipotent being could eliminate all evil without the loss of any greater good. And yet the atheist needs some such proposition to prove that the existence of God and evil are logically contradictory: specifically, she needs some proposition that is necessarily true and that, combined with the fact that evil exists, entails that God does not exist. No one, so far, has been able to do this. The charge of contradiction that Mackie and others bring is a strong one, and the burden of proof is on them to show exactly what the contradiction is. Unless they can do so, there is no good reason to conclude that the existence of evil proves that there is no God.