What Is the Problem of Evil and How Philosophers Respond

The Oldest Challenge to Theism

If a perfectly good, all-knowing, and all-powerful God exists, why is there so much suffering in the world? This question, one of the oldest and most persistently troubling in the history of philosophy and theology, is called the problem of evil. It has driven some people from faith, deepened the convictions of others, and occupied the greatest minds in Western philosophy for more than two thousand years.

The problem is not merely an abstract puzzle. It is driven by the visceral reality of human suffering: children dying from cancer, innocent people killed by natural disasters, the systematic cruelty of genocide, the anguish of chronic illness, and the casual indifference of a universe that extinguishes countless lives. When confronted with these realities, the gap between the concept of a perfectly good and omnipotent God and the world as it actually exists can seem not merely puzzling but unbridgeable.

The Logical Problem of Evil

Philosopher J.L. Mackie stated the sharpest version of the problem in his 1955 paper Evil and Omnipotence. The logical problem of evil argues that the following three propositions cannot all be simultaneously true:

1. God is omnipotent (all-powerful).
2. God is omnibenevolent (perfectly good).
3. Evil exists.

The argument proceeds as follows: an all-powerful God could eliminate all evil. An all-good God would want to eliminate all evil. If both are true, evil should not exist. But evil does exist. Therefore, at least one of the first two propositions must be false, and the traditional conception of God as both omnipotent and omnibenevolent is logically incoherent.

Mackie's formulation was intended to show that theism is not merely false but logically contradictory. If he is right, no amount of evidence or argument can vindicate theism, because the concept of God as classically defined is as self-contradictory as a married bachelor. Many philosophers and theologians have disputed whether the logical problem succeeds, and the most widely discussed response is Alvin Plantinga's Free Will Defense.

The Free Will Defense

Alvin Plantinga's response to the logical problem, developed in his 1974 book The Nature of Necessity, argues that it is possible that God cannot create free beings who always freely choose good. Freedom, by definition, requires the genuine possibility of choosing evil. A being who could only choose good would not be genuinely free. Therefore, creating free beings necessarily involves accepting the possibility that they will choose evil.

Plantinga's argument does not claim that God lacks the power to prevent evil in some brute sense, but that creating free beings who never do evil may be a logical impossibility, not because of any limitation on God's power but because genuinely free choices are not the sort of thing that can be externally determined even by an omnipotent creator. A God who prevents every free choice of evil would simply not be creating free beings at all.

Most philosophers grant that Plantinga's Free Will Defense succeeds against the strict logical problem: it is at least possible that God and moral evil (evil arising from human choices) can co-exist. However, the defense is generally considered inadequate for natural evil, suffering caused by earthquakes, floods, disease, and other non-human causes, since these do not arise from human free choices and an omnipotent God could presumably eliminate them without limiting human freedom.

The Evidential Problem of Evil

Even if the logical problem can be deflected, a more modest but arguably more powerful version remains. The evidential problem of evil, associated particularly with philosopher William Rowe, argues not that the existence of evil makes theism logically impossible but that it makes theism highly improbable.

Rowe's formulation draws attention to gratuitous evil: evil that serves no discernible higher good. An example: a fawn dies slowly in a forest fire, suffering intensely for days, with no human witness and no apparent moral purpose served by its suffering. An omnipotent and omniscient God could have prevented this suffering without any loss of greater good. The existence of such apparently pointless suffering, which seems to occur constantly throughout nature and history, constitutes strong evidence against the existence of a God who is both all-powerful and perfectly good.

The response to gratuitous evil often involves skeptical theism: the argument that we are not in a position to judge whether seemingly pointless suffering serves no higher purpose, because our cognitive limitations prevent us from seeing all the goods and connections that an omniscient God might see. Just as a young child cannot understand why a painful medical procedure is actually for their good, we may be unable to perceive the reasons that make apparent gratuitous evils necessary from God's perspective.

Theodicy: Justifying the Ways of God

A theodicy is an attempt not merely to show that God and evil are logically compatible but to provide a positive account of why God permits evil. Several theodicies have been influential in the tradition.

The soul-making theodicy, associated with John Hick, draws on the thought of the early Christian theologian Irenaeus. It argues that humans were created not as finished moral beings but as beings with the potential for moral and spiritual growth, and that this growth is only possible in a world containing genuine challenges, hardship, moral temptation, and real consequences. A world without pain, struggle, and the genuine possibility of failure would be a world where moral character could not develop. Suffering, on this view, is the necessary condition for the formation of virtuous souls.

The greater good theodicy holds that specific evils are necessary conditions for specific goods that could not be achieved otherwise: courage requires real danger, compassion requires real suffering, forgiveness requires real wrongdoing. A world without evil would be a world without the most admirable forms of human virtue and response.

Responses From Non-Western Traditions

The problem of evil is primarily a challenge for Western monotheism because it presupposes a single omnipotent, omniscient, and omnibenevolent creator. Other religious and philosophical traditions approach the question differently. Buddhist philosophy does not posit a creator God and addresses suffering through the Four Noble Truths: suffering exists, arises from craving and attachment, can cease, and the path to its cessation involves the Eightfold Path. Suffering is a central feature of existence to be understood and transcended rather than a problem for theodicy.

Hinduism offers multiple perspectives, including the view that suffering arises from karma and the attachment of the self to the material world, and liberation (moksha) involves transcending both. Polytheistic traditions typically do not require their deities to be perfectly good or omnipotent, dissolving the logical form of the problem entirely, though they face other theological challenges.

Does the Problem Succeed?

After centuries of debate, most philosophers of religion conclude that the logical problem of evil has been answered by the Free Will Defense, but that the evidential problem remains a serious challenge to classical theism. The degree to which gratuitous evil makes theism improbable depends substantially on prior probabilities and how much weight one gives to other arguments for and against the existence of God.

For many people, the problem of evil is less a technical argument than an existential challenge: not an intellectual puzzle but a lived confrontation with suffering that resists any theodicy's power to console. The book of Job engages this experiential dimension with more honesty than most philosophical arguments, neither explaining the suffering away nor resolving it, but placing it before a God who answers from the whirlwind. Philosophy can clarify the problem, but some dimensions of it may resist philosophical solution entirely.

Conclusion

The problem of evil is one of the most powerful challenges to religious belief, forcing careful reflection on what we mean by God's power, goodness, and knowledge, and what relationship between creator and creation makes sense of the world's suffering. The philosophical responses, from the Free Will Defense to skeptical theism to soul-making theodicy, each illuminate different aspects of the problem while leaving others unresolved. The question of why a perfectly good God would permit the suffering of innocents remains, after millennia, one of the most urgent and unfinished questions in human thought.