Program / Course 15: The Problem of Evil and Suffering / Lesson 1.2
What you will learn
- Define the logical problem of evil and state it as a set of propositions.
- Explain what it means for a set of claims to be logically inconsistent.
- Describe the extra premises that the argument needs and why believers question them.
- Understand why many philosophers, including many atheists, now think the logical problem has been answered.
The big idea
The logical problem of evil claims that it is impossible for an all-powerful, wholly good God and evil both to exist, so that anyone who believes in both is contradicting themselves. To make this claim stand, the critic must add hidden assumptions: that a good being removes all evil it can, and that an all-powerful being can do anything at all. Christians have questioned these assumptions. Most philosophers today, believers and nonbelievers alike, think the strict logical version has failed, and that the real debate lies elsewhere.
Key terms
- Logical problem of evil
- The claim that the existence of God and the existence of evil cannot both be true, because they contradict each other.
- Inconsistent set
- A group of statements that cannot all be true at once. If one is true, at least one other must be false.
- Proposition
- A statement that is either true or false, such as God is good.
- Premise
- A statement offered as a reason in an argument. A hidden premise is one the argument needs but does not state.
- Possible world
- A way things could have been, used by philosophers to test whether a claim is consistent.
- Necessary and sufficient
- A condition is necessary if the result cannot happen without it, and sufficient if it guarantees the result.
- Burden of proof
- The duty to give reasons. In an argument for inconsistency, the one who claims a contradiction must show it.
Background
The logical problem is the strongest and simplest form of the argument. It does not say that evil makes God unlikely. It says that evil makes God impossible. If that were proved, no amount of religious experience or evidence for God could save theism, because a contradiction cannot be true.
The best known modern statement is by the Australian philosopher J. L. Mackie in an article called Evil and Omnipotence, published in 1955. Mackie was an atheist, and he called the believer’s position not merely unsupported but positively irrational. For about twenty years the article set the agenda. Then Alvin Plantinga, an American Protestant philosopher, argued that the contradiction could not be shown. Many philosophers who disagree with Plantinga about God now agree with him on this point.
The lesson does not need any symbolic logic. It needs patience with one fact: to prove that a set of statements is inconsistent, you must either find a flat contradiction in them or show that they contradict one another when joined by premises that are necessarily true.
Step-by-step explanation
Step 1: The three claims
Mackie begins with three propositions. First, God is omnipotent, that is, all-powerful. Second, God is wholly good. Third, evil exists. He says that these three seem to be in tension, and that one cannot consistently hold all three.
Look carefully at the claim. The three statements, taken just as they stand, do not contradict one another in the way that It is raining and It is not raining do. Nothing in them says what a good being must do, or what an all-powerful one can do. So Mackie adds more.
Step 2: The added premises
Mackie adds two principles. The first is that good is opposed to evil in such a way that a good being always eliminates evil as far as it can. The second is that there are no limits to what an omnipotent being can do. With these in place the argument runs: a wholly good God would eliminate every evil he can, an omnipotent God can eliminate every evil, so if God existed there would be no evil. But there is evil. So God does not exist.
The argument is valid. The conclusion follows if the premises are true. The question is whether the premises are necessarily true, since a mere contradiction needs more than plausible premises. A believer can reject either of them without any contradiction.
Step 3: Where believers push back
Take the claim that a good being eliminates all the evil it can. A parent may allow a child to endure a painful operation, because the operation brings a greater good. A teacher may permit a student to struggle. Most people agree that a good being may permit some evil if there is a good reason, so the first principle seems too strong as stated. The critic can reply that very great evils need much weightier reasons, and that is true. But then the dispute turns from logic to whether such reasons exist, which is a different question.
Take the second claim, that omnipotence has no limits. Christian thinkers have long said that omnipotence means power to do whatever can be done, not power to do the logically impossible. God cannot make a square circle, or make a person freely choose something while forcing the choice. Aquinas states that what implies a contradiction does not fall under God’s power, and that this is not a weakness. So whether God can remove every evil without removing some good depends on what the goods are.
Step 4: Showing that two claims can both be true
To answer a claim of inconsistency, it is enough to find one possible situation in which all the claims are true. If there is even a possible scenario in which God is all-powerful, wholly good and also permits evil for a good reason, then the claims are consistent. That is why Plantinga’s reply focuses on a story that merely might be true. It does not need to be the true story.
This is an important feature of the logic. A defender need not claim to know God’s reasons. The defender needs only to show that some reason is possible. The critic, who made the strong claim of impossibility, has the burden of showing that no such possibility exists. The next module studies the main candidate, the free-will defense.
Step 5: What survives
Many philosophers conclude that the logical problem has failed. Mackie himself later granted that the free-will defense showed more than he first allowed, though he was not fully convinced by it. William Rowe, a leading critic of theism, wrote in 1979 that it is generally agreed that the logical problem has been answered, and that the debate has moved to the evidential problem.
That does not mean that the matter is closed, nor that suffering has stopped being a difficulty. A claim that two ideas are consistent does not show that either is true. It shows only that a certain argument does not force an unbeliever’s conclusion. The more serious difficulty, the sheer amount and kind of suffering, remains for the next lesson.
- Why does Mackie need to add premises to his three claims?
- Is it always true that a good being removes all the evil it can? Give a case where it seems false.
- What do Christians mean when they say that omnipotence does not include the logically impossible?
- Why is it enough to show that a story is possible, and not that it is true, in order to answer a claim of inconsistency?
- Does the failure of the logical problem make suffering any easier to bear?
- What would a critic need to add to turn a possible reason into an impossible one?
Examples
Surgery
A surgeon cuts into a patient who would otherwise die. The patient suffers, and the surgeon could have avoided that suffering by not operating. The surgeon is not therefore bad. This shows that permitting a lesser evil can be consistent with goodness when a greater good is in view. (An illustration, which does not by itself answer the larger question.)
The impossible task
Suppose someone says that if God is all-powerful, he can make a stone so heavy that he cannot lift it. Most philosophers say that this describes nothing coherent, and that failure to do it shows no weakness in God. The case helps to see why omnipotence is usually defined as power to do what is possible.
A consistency test
Consider the statements My neighbor is rich and My neighbor drives an old car. They seem to clash, but one can easily imagine a rich person who loves an old car. Showing that two claims are consistent only requires one coherent way for both to be true.
Different perspectives
Catholic
Thomas Aquinas taught that God can do all things that are possible in themselves, and that evil is permitted by God because he is able to bring good out of it. Catholic theology has therefore never accepted that omnipotence means doing the contradictory, and has long held that God permits evil without willing it as a goal.
Orthodox
Orthodox theologians are generally wary of treating God’s power and goodness as abstract properties in a logical puzzle. They speak of a personal God revealed in Christ. They would accept that the logical argument fails, yet would say that the real response to evil is found in the incarnation and in the defeat of death.
Protestant
Plantinga and many other Protestant philosophers hold that the logical argument has been met by showing consistency. Reformed theologians in particular stress that God’s purposes in permitting evil are good but often hidden, which fits the claim that the critic cannot show their impossibility.
Philosophical critics
Mackie held that the believer needed to modify the traditional concept of God. Some critics argue that the free-will defense, even if consistent, leaves problems, and that a world in which God prevented more evil would have been better. Most now put their weight on the evidential argument.
Why it matters
Knowing the exact shape of the logical problem protects a student from two mistakes: giving in to a claim of contradiction that has not been proved, and treating a successful reply as if it had solved the pain. It also teaches a method that applies to all arguments: find the hidden premises and ask whether they must be true.
Common misunderstandings
Misunderstanding: If the logical problem has been answered, then the problem of evil is solved.
Correction: Answering the logical problem shows only that belief in God and in evil is not contradictory. The evidential problem, which concerns how likely God is given the amount of suffering, and the personal problem of grief remain.
Misunderstanding: Omnipotence means God can do absolutely anything, including the self-contradictory.
Correction: The mainstream Christian tradition holds that omnipotence is power to do what can be done. Contradictions are not things at all, so failing to do them is no limit.
Misunderstanding: The believer has to know God’s actual reason for permitting evil.
Correction: To meet the logical argument it is enough to show that a good reason is possible. Claiming to know the actual reason is a much larger task and is not needed here.
Knowledge check
What does the logical problem of evil claim?
It claims that God’s existence and the existence of evil cannot both be true, since they contradict one another. If that were shown, belief in an all-powerful and wholly good God would be irrational whatever other evidence existed. It differs from the evidential problem, which claims only that evil makes God’s existence unlikely.
Which two added premises does Mackie use, and why are they important?
He assumes that a good being always eliminates as much evil as it can, and that an omnipotent being can do anything. The argument is valid with these premises, but they are not obviously necessary truths. If either is false, the contradiction disappears, so the whole argument depends on them.
Why is a merely possible reason enough to answer a charge of inconsistency?
To say that claims are inconsistent is to say that they cannot all be true in any possible situation. A single coherent scenario in which all of them are true therefore refutes that charge. The defender need not claim that the scenario is the actual one, only that it could be.
What happened to the logical problem in later philosophy?
After Plantinga’s work in the 1970s, most philosophers, including William Rowe and eventually Mackie himself in part, accepted that a contradiction had not been shown. The discussion shifted to the evidential problem, which asks whether the amount and kind of evil make theism improbable.
Think it through
- Can you think of a case from your own life where a good person allowed pain for a greater purpose? Did you understand the purpose at the time?
- Why might a skeptic find the consistency reply unsatisfying even if it is logically sound?
- What is the difference between an answer that is logically successful and an answer that consoles?
Independent assignment
Find the hidden premises
In your own notebook, write about 400 words. Write out Mackie’s argument in numbered steps, marking the two added premises. Then, for each added premise, write a short paragraph explaining either why it seems true or why a Christian might reject it. End with one sentence stating what you think the argument has and has not shown. Keep the work private.
Further study
- Stanford Encyclopedia of Philosophy, The Problem of Evil Read the section on the logical problem and its history.
- Alvin Plantinga, God, Freedom, and Evil Read the opening chapters in which Plantinga restates the logical problem before answering it.
- Thomas Aquinas, Summa Theologiae Look up the question on God’s omnipotence in the First Part and see how Aquinas treats what cannot be done.
- Genesis 18:25 Abraham asks whether the Judge of all the earth will do right.