Introduction to the Problem of Evil

The Problem of Evil

Earlier, we discussed the most popular and intuitive argument for thinking there is a god: the design argument. That argument appealed to our ordinary observations of the intricacy and orderliness of the universe as evidence of a divine Designer. The present argument is the “evil twin” of the design argument: the problem of evil. It’s the most popular and intuitive argument for thinking there is no god. Like the design argument, it appeals to our ordinary observations, but in this case, the observations are of disorder of various sorts – in particular, evils.

There are two broad kinds of evil the argument appeals to as evidence of the non-existence of a god: moral evil and natural evil. Moral evil is “person-on-person evil” – evil committed by persons against other persons (or by a person against themselves). Moral evils run the gamut from such horrendous wickedness as genocide, slavery, torture, murder, and rape to the more mundane occurrences of “small” lies and petty theft. By contrast, natural evils are bad things that are caused by impersonal forces, such as hurricanes, tornadoes, tsunamis, plagues, the law of predation (i.e., the fact that the only way for carnivores to stay alive is to kill and eat other conscious creatures), diseases, depression, etc.

The basic idea is then that the world is full of moral and natural evil, but a god who is all-knowing, all-powerful, and perfectly good wouldn’t allow such evil; therefore, there is no god – or at least, no god like that. The argument can stated more carefully as follows:

1. If an all-knowing, all-powerful, perfectly good god exists, then evil does not exist.
2. It’s not the case that evil does not exist.
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3. Therefore, it’s not the case that an all-powerful, all-knowing, perfectly good god exists.

The argument is an instance of modus tollens (1. If P, then Q; not-Q; therefore, not-P), and so it's deductively valid; so, the only way to rationally resist the conclusion is to show that at least one of the premises is false or otherwise unjustified. Well, why are we supposed to accept the premises?

The support for (1) goes back to at least Epicurus (Hume quotes Epicurus in his Dialogues Concerning Natural Religion): “Is he [God] willing but unable to prevent evil? Then he is impotent. Is he willing but unable? Then he is malevolent. Is he both willing and able? Whence then is evil?” The logic of the reasoning here can be unpacked and stated more rigorously:

1. If God is all-knowing and all-powerful, then God is able to prevent evil.
2. If God is perfectly good, then God is willing to prevent evil.
3. If God is both able and willing to prevent evil, then evil does not exist.
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4. Therefore, if God is all-knowing, all powerful, and perfectly good, then evil does not exist.[1]

Premise 2 is supported by observation of and testimony about the evil in the world: we observe, and hear news of, the moral evils of genocide, slavery, torture, murder, rape, kidnappings, etc., and of the natural evils of hurricanes, tornadoes, tsunamis, famine, drought, diseases, depression, etc.



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Notes:
[1] Proof: Let: P=God is all-knowing; Q=God is all-powerful; R=God is able to prevent evil; S=God is perfectly good; T=God is willing to prevent evil; U=Evil does not exist. Then the proof runs as follows:

1. (P∧Q) → R Premise
2. S → T Premise
3. (R∧T) → U Premise
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4. (P∧Q) ∧ S Assumption
5. P∧Q 4 ∧E
6. R 1, 5 MP
7. S 4 ∧E
8. T 2, 7 MP
9. R∧T 6, 8 ∧I
10. U 3, 9 MP
11. ((P∧Q) ∧ S) → U 4-10 →I

Q.E.D.