© Michael Lacewing
The problem of evil is widely considered to be the most powerful argument against the existence of God. The central issue is whether evil, as it occurs in this world, either proves that God, as traditionally conceived, does not exist or at least makes the belief in such a God unreasonable. In this handout, we consider one version of the problem – the logical problem.
God is traditionally understood to be supremely good, omnipotent and omniscient. The existence of evil causes problems for believing that such a being exists. Throughout the discussion, I shall take ‘God’ to refer to a being that is supremely good, omnipotent and omniscient. Here’s the argument:
1 If God is supremely good, then he has the desire to eliminate evil.
2 If God is omnipotent, then he is able to eliminate evil.
3 If God is omniscient, then he knows that evil exists and knows how to eliminate it.
4 Therefore, if God exists, and is supremely good, omnipotent and omniscient, then evil does not exist.
5 Evil exists.
6 Therefore, a supremely good, omnipotent and omniscient God does not exist.
Two versions of the argument There are two versions of this argument.
The logical problem of evil claims that the mere existence of evil is logically incompatible with the existence of God. In other words, the following claims cannot all be true:
1 God is supremely good.
2 God is omnipotent.
3 God is omniscient.
4 Evil exists.
If any three of the claims are true, the fourth must be false. On this version, the argument above is deductive.
The evidential problem of evil makes a weaker claim. It claims that the amount and
distribution of evil that exists is good evidence that God does not exist. On this version, the argument above is inductive. We shall not discuss this version in this handout.
Two types of evil To understand the argument, we need to be clear on what ‘evil’ means in this context. ‘Evil’ usually refers to the morally wrong actions or motives of human beings.
So we say that Hitler was evil in trying to eradicate the Jews from Europe or that ethnic cleansing is an evil policy. This is moral evil.
But this isn’t the only kind of evil the problem of evil is talking about. There is also natural

evil, also known as ‘physical evil’, which refers to suffering caused by natural events and processes, e.g. the suffering caused by earthquakes, diseases, the predation of animals on each other, and so on.
In the first instance, the two types of evil are distinct. What people choose to do to each other is not usually the result of natural events. Sometimes it is: famine may drive people to stealing and killing; but this is the exception. And natural events are not usually the result of what people choose to do. Again, sometimes they are – the results of global warming could be an example.
We need to keep both types of evil in mind when we look at responses to the problem of evil.
In particular, some responses may solve the problem of moral evil, but don’t answer the problem of natural evil.
Mackie outlines the logical problem of evil as above, that (1)–(4) are inconsistent, although he (mistakenly) omits the claim that God is omniscient. He argues that that we need to add two additional claims before we get inconsistency:
5 Good is opposed to evil, such that a good thing eliminates evil as far as it can.
6 There are no limits to what an omnipotent thing can do.
One way out of the inconsistency is to give up one of the claims. For example, someone might deny (4), arguing that evil doesn’t exist. What we call evil isn’t really evil. An alternative is to deny (6): there are limits to what an omnipotent God can do. We’ll consider this claim at length in the discussion below. Mackie accepts that such moves – if they can be defended – solve the problem.
He then considers a series of common responses which, he argues, do not solve the problem.
We will look at three: the claims that good can’t exist without evil, that the world is better with some evil in it than it could be if there were no evil, and that evil is the result of free will.
Good can’t exist without evil This is a very general claim. It claims that there can be no good without some evil. (We will look at the more specific claim that some goods that exist can’t exist without evil below.) As such, it denies either (5) or (6) or both. Being omnipotent, God can presumably do anything that is logically possible. But if it is logically impossible for good to exist without evil, then God can’t create a world in which good can exist without evil. And evil does not oppose good, but in some sense is necessary for it.

In what sense? By analogy, someone might argue that one colour requires the existence of other colours, e.g. to generate a contrast. But, Mackie argues, there is no reason why everything couldn’t be red. Of course, if everything was red, then we probably wouldn’t notice this (it would just be ‘how things are’) and we wouldn’t have a word for red. But that is a claim about how we think and talk. It doesn’t show that things wouldn’t be red. Likewise, if there was no evil, we wouldn’t know that things were good; but that doesn’t show that God can’t create a world in which there is good but no evil. What God can do isn’t restricted by human language or thought.
An alternative is to argue that evil doesn’t ‘exist’ in any positive sense – it is simply the absence of good. This would show that good and evil are logically opposed, like red and
‘not-red’. But that still doesn’t show why God couldn’t create a world which has no absence of good, a ‘fully good’ world.
Finally, suppose we allow that good can’t exist without evil. That only shows that the world, to contain any good at all, must contain some evil. In that case, the existence of God isn’t logically incompatible with the existence of evil. But surely such a God would not allow so
much evil – the evidential problem of evil is not yet solved.
The world is better with some evil in it than it could be if there were no evil We can develop the previous point by focusing on specific kinds of good and evil. While it may or may not be true that any good requires evil, there are some goods that clearly require some evil. The logical problem of evil assumes that God has the desire to eliminate all evil. But this isn’t true if some evil is necessary for a greater good. In particular, there are virtues, such as sympathy, benevolence and courage, that require suffering to exist. A universe without suffering would be a universe without these virtues; and a universe without either suffering or virtue would be a worse universe than one in which there is both suffering and virtue. The evil of suffering makes the good of virtue possible.
Mackie puts the point like this: call suffering a ‘first-order’ evil and pleasure a first-order good. ‘Second-order’ goods, such as virtues, aim at maximising first-order goods (pleasure) and minimising first-order evils (suffering). But second-order goods are impossible without first-order evils. We can now argue that these second-order goods are more important or more valuable than first-order goods, so a universe that contains them is significantly better than a universe with only first-order goods, so much so that even the existence of first-order evils does not outweigh second-order goods. So God brings about a universe with second-order goods and first-order evils.
Mackie objects, however, that we have left second-order evils, such as malevolence, cruelty and cowardice, out of consideration. We have only explained how a universe with first-order evils (and second-order goods) could be better than one without first-order evils. But we haven’t explained how a universe, such as ours, that has both first- and second-order evils is better than one without both. We haven’t shown how the existence of God is compatible with the existence of second-order evils.
Evil is due to human free will Perhaps we can solve this challenge by supplementing the previous answer by an appeal to free will. Second-order evils are the result of free will. Being morally imperfect, we do not always use our free will for good, but sometimes bring about evil. However, this is compatible with the existence of God because being free is such a significant good that it outweighs the evil that we bring about. The universe is better with free will and second-order evils than it would be without either.
Why doesn’t God just make us choose what is good? Because, we can reply, this isn’t logically

possible. To be free is for one’s choices not to be determined. If God made us choose good, then our choices would be determined, so we wouldn’t be free.
However, Mackie objects, second-order evils are not logically necessary for free will, in the way first-order evils are necessary for second-order goods.
1 It is possible to freely choose what is good on one occasion.
2 If it is possible to freely choose what is good on one occasion, then it is logically possible to freely choose what is good on every occasion.
3 God can create any logically possible world.
4 Therefore, it is possible for God to create a world in which creatures are free and freely choose only what is good.
5 God would eliminate evil that is not necessary for a greater good.
6 Second-order evil is not necessary for a greater good.
7 Second-order evil exists.
8 Therefore, God does not exist.
On the logical problem of evil Why does God allow evil? If we try to answer this question, to give a reason why God allows evil, we offer a theodicy. The three responses that Mackie discusses are theodicies. Plantinga takes a different approach. Suppose we don’t, or even can’t, know why, in fact, God allows evil. This isn’t enough to show that God’s existence is
inconsistent with the existence of evil. We don’t need to discover and defend the true
explanation for why evil exists. All we need to do, to defeat the logical problem of evil, is show that the existence of God is consistent with evil. Two (or more) claims are consistent if they can both (or all) be true together. To show this, we don’t need to show that the claims
are true. Plantinga calls this approach a ‘defence’ rather than a theodicy.
Our discussion of Mackie showed that God’s existence is not inconsistent with some evil. For example, first-order evils are necessary for second-order goods. The difficulty that remained was whether second-order evil is consistent with the existence of God. Plantinga develops the argument from free will, not as a theodicy, but as a defence.
The free will defence On pp. 29-34, Plantinga presents the heart of the argument. He first presents these definitions:

1 To be free is to be able to do or refrain from some action, not to be causally determined to act in one way or another. (One can be free and still be predictable.)
2 A morally significant action is one which it is either right or wrong to perform. (An action that is permissible to do or omit, e.g. have a banana for breakfast, is not morally significant.)
3 A creature is significantly free if it is free to do or refrain from morally significant actions.
4 Moral evil is evil resulting from the actions of significantly free creatures. (This contrasts with natural evil.)
Plantinga then offers the following argument (p. 30).
1 A world containing creatures that are significantly free is better than a world containing no free creatures.
2 God can create significantly free creatures.
3 To be significantly free is to be capable of both moral good and moral evil.
4 If significantly free creatures were caused to do only what is right, they would not be free.
5 Therefore, God cannot cause significantly free creatures to do only what is right.
6 Therefore, God can only eliminate the moral evil done by significantly free creatures by eliminating the greater good of significantly free creatures.
If the conclusion, (6), is asserted as a true claim, this argument is a form of the free will theodicy. The free will defence, however, only claims that (6) is possible. If this is possible, then the existence of evil, including second-order evil, is logically consistent with the existence of God.
Natural evil The free will defence only tackles moral evil. So how do we make the existence of natural evil consistent with the existence of God? Plantinga provides an argument (p. 57), derived from Augustine. Augustine argues that natural evil is the result of the free actions of
non-human creatures, namely Satan and his fallen angels. The traditional story goes that the
Devil was an angel, created by God, endowed with free will. But he rebelled against God, and since then has sought to bring evil into the world. Natural evil is one of the effects of his actions, so natural evil is a form or consequence of moral evil. While Augustine argued that this was a true explanation of natural evil, Plantinga’s free will defence only needs to claim that this is possible.
How good is free will? Plantinga’s claim (1) compares a world with creatures that are free with a world without such creatures. We can object that this leaves out other possibilities.
Even if free will is a great good, that doesn’t mean we should never interfere with it. For example, if we see someone about to commit murder and do nothing about it, it is no defence to appeal to how wonderful it is that the murderer has free will. To eliminate some evils, one has to eliminate certain instances of free will. But this type of selective interference is compatible with the existence and goodness of free will; it doesn’t eliminate a greater good. So God would interfere in this way.
We can challenge this. If God always interfered to prevent us from causing evil, then this is equivalent to his causing us to do good. In that case, we don’t have free will at all.
We can refine the objection. God could interfere just on those occasions on which we would bring about terrible evil. Or again, God could have given us free will without giving us the power to commit terrible evil. The point is that free will doesn’t seem such a good thing that each occasion of choosing freely is a good thing. Some choices are better eliminated.
Wouldn’t a limited kind of free will have been better?

One response, from John Hick, is that the value of free will depends on what one can do with it. A world in which we couldn’t harm each other – either because we didn’t have the power to do so or because God always interfered to stop us – would also be one in which we would have very little responsibility for each other’s well-being (Evil and the God of Love, Ch. 16,
§3)
Whether or not this justifies the moral evil that human beings do, we can raise the objection again regarding Satan. Is the free will of Satan so good that it outweighs all the natural evil that he has caused? Surely a world without Satan would be a better world, and a world that
God could have created. If Satan exists, then this is logically inconsistent with the existence of
God and the free will defence fails to justify natural evil.