Lesson · 4 min Stretch
The Problem of Evil
In one line If God is all-good and all-powerful, why is there suffering? The question has a logical form and an evidential one.
An ancient puzzle, often credited to Epicurus and put sharply by David Hume, asks: is God willing to prevent evil, but not able? Then God is not all-powerful. Able, but not willing? Then God is not all-good. Both able and willing? Then where does evil come from?
In 1955 J. L. Mackie pressed the logical form: a wholly good, all-powerful God and evil cannot both exist. Later, William Rowe offered the evidential form. He described a fawn burned in a forest fire, suffering for days with no one to see. Even if God and evil are logically compatible, he argued, suffering like this makes God’s existence less likely.
The 1755 Lisbon earthquake, which killed tens of thousands on a holy day, made the question vivid for Voltaire.
Go deeper
Voltaire answered the Lisbon earthquake with a poem attacking the claim that all is well. Rousseau replied in a letter that much of the harm came from human choices, such as packing twenty thousand houses of six or seven stories into one city. The exchange helped shape Candide, published in 1759, with its mocking refrain about the best of all possible worlds.
The children’s ward
A parent on a children’s ward asks the hospital chaplain why a good God would let her child fall ill.
The chaplain does not hurry to an answer. She knows the question is old and serious, and she says so. Philosophers distinguish the parent’s grief, which needs company now, from the argument, which needs careful thought at another time.
Try this today Think of one case of suffering, and ask what good, if any, could only be reached by allowing it.
Cite or share this lesson
A plain reference you can paste into notes or an essay:
Quest2Reason. “The Problem of Evil.” https://quest2reason.com/learn/lesson/the-problem-of-evil. Accessed 13 November 2026.
Sources
- Stanford Encyclopedia of Philosophy, “The Problem of Evil” — Surveys the logical and evidential problems and the main replies.
- Internet Encyclopedia of Philosophy, “The Logical Problem of Evil” — Covers Mackie’s argument and Plantinga’s reply.
- Internet Encyclopedia of Philosophy, “The Evidential Problem of Evil” — Covers Rowe’s fawn and the debate over gratuitous suffering.
- Wikipedia, “1755 Lisbon earthquake” — Describes the disaster and its effect on Voltaire and Rousseau.
- David Hume, Dialogues Concerning Natural Religion, Part X — Philo puts Epicurus’s old questions: willing but not able, able but not willing.