Problem of Evil - Detailed Arguments - Logical Problem of Evil

Logical Problem of Evil

The originator of the problem of evil is often cited as the Greek philosopher Epicurus, and this argument may be schematized as follows:

1. If an all-powerful and perfectly good god exists, then evil does not.
2. There is evil in the world.
3. Therefore, an all-powerful and perfectly good god does not exist.

This argument is of the form modus tollens, and so is logically valid - if its premises are true, the conclusion follows of necessity. However, as it is unclear precisely how the existence of an all-powerful and perfectly good God guarantees the non-existence of evil, it is unclear whether the first premise is true. To show that it is plausible, subsequent versions tend to expand on this premise, such as this modern example:

1. God exists.
2. God is omnipotent, omniscient, and perfectly good.
3. A perfectly good being would want to prevent all evils.
4. An omniscient being knows every way in which evils can come into existence.
5. An omnipotent being, who knows every way in which an evil can come into existence, has the power to prevent that evil from coming into existence.
6. A being who knows every way in which an evil can come into existence, who is able to prevent that evil from coming into existence, and who wants to do so, would prevent the existence of that evil.
7. If there exists an omnipotent, omniscient, and perfectly good being, then no evil exists.
8. Evil exists (logical contradiction).

Both of these arguments are understood to be presenting the logical problem of evil. They attempt to show that the assumed propositions lead to a logical contradiction and therefore cannot all be correct. Most philosophical debate has focused on the propositions stating that God cannot exist with, or would want to prevent, all evils (premises 3 and 6), with defenders of theism arguing that God could very well exist with and allow evil in order to achieve a greater good.

One greater good that has been proposed is that of free will, famously argued for by Alvin Plantinga in his free will defense. The first part of this defense accounts for moral evil as the result of free human action. The second part of this defense argues for the logical possibility of "a mighty nonhuman spirit" such as Satan who is responsible for so-called 'natural evils', including earthquakes, tidal waves, and virulent diseases. Many philosophers accept that Plantinga successfully solves the logical problem of evil, as he appears to have shown that God and evil are logically compatible, though others demur.