Problem of Evil Logical

Overview and Classical Formulation

The logical problem of evil is a central argument in the philosophy of religion that claims there is a strict logical inconsistency between the existence of evil and the existence of a God who is omnipotent (all-powerful), omniscient (all-knowing), and omnibenevolent (wholly good). Unlike evidential versions of the problem of evil, which argue that evil makes God’s existence unlikely, the logical version aims to show that the two are logically incompatible—that it is impossible for both to be true simultaneously.

A version traditionally attributed to Epicurus and later popularized by David Hume in Dialogues Concerning Natural Religion presents the tension in a quasi-dialogical form:

• If God is willing to prevent evil but not able, then he is not omnipotent.
• If he is able but not willing, he is malevolent.
• If he is both able and willing, whence evil?
• If he is neither able nor willing, why call him God?

In modern analytic philosophy, J. L. Mackie (1917–1981) gave a canonical and more formally structured version. Mackie argued that standard theistic claims, together with a few seemingly obvious moral principles, generate a contradiction. The theist affirms:

1. God exists and is omnipotent.
2. God exists and is wholly good.
3. Evil exists.

Mackie adds principles such as:

• A good being always eliminates evil as far as it can.
• There are no limits on what an omnipotent being can do (except logical impossibilities).

From these, he contends that if an omnipotent, perfectly good God existed, no evil would exist at all. Since evil plainly exists, Mackie concludes that the traditional theistic God cannot exist.

This form of the argument is deductive: if its premises are jointly consistent and its inferences valid, the conclusion follows with necessity rather than probability.

Major Theistic Responses

The logical problem of evil has prompted a range of theistic replies. These responses typically reject, qualify, or reinterpret one or more of the auxiliary principles (such as what a good being would do, or what an omnipotent being can do), while preserving the core theistic claims.

1. Free Will Defense

The most influential response in contemporary analytic philosophy is the Free Will Defense, associated above all with Alvin Plantinga. Plantinga does not attempt to give a full theodicy (an explanation of why God actually allows evil), but instead offers a defense: a logically possible scenario under which God and evil can coexist without contradiction.

The core idea is that:

• Moral agents with significant freedom are a great good.
• It may be that even an omnipotent God cannot strongly determine that such agents freely always choose good; freedom to choose good entails freedom to choose evil.
• Thus, some moral evil may be an unavoidable consequence of creating significantly free creatures.

Plantinga introduces the notion of transworld depravity: the possibility that every feasible world containing significantly free creatures would involve some of them choosing evil at least once. If this is possible, then it is not logically inconsistent for God to create free beings and yet be unable to ensure they always do right.

On this account, the crucial principle “a good being always eliminates every evil it can” is rejected as too strong. A perfectly good God might allow some evil in order to secure a greater good—here, the existence of free creatures and their capacity for genuine moral responsibility.

Although Plantinga’s defense primarily addresses moral evil (evil resulting from free actions), he also suggests that natural evil (suffering from disease, earthquakes, etc.) might conceivably be due to the actions of nonhuman free agents (e.g., fallen angels), or might be integrated into larger goods accessible only in an afterlife. The emphasis, however, is on logical possibility rather than empirical plausibility.

2. Revisions of Omnipotence and Goodness

Other responses focus on clarifying the divine attributes:

• Omnipotence: Many philosophers argue that omnipotence does not include doing what is logically impossible. If it is logically impossible to both grant creatures significant freedom and guarantee that they never choose evil, then God’s inability to do so does not limit omnipotence in any problematic sense.

• Goodness: Critics of the argument claim that the principle “a good being always eliminates all evil it can” is oversimplified. A more nuanced principle holds that a good being eliminates evil unless allowing it is necessary for a greater good or to prevent a worse evil. Under this weaker principle, the mere existence of evil does not logically conflict with divine goodness.

By weakening or refining these auxiliary assumptions, theists aim to remove the alleged logical contradiction while leaving open evidential questions about whether God in fact exists.

3. Soul-Making and Other Theodical Themes

Although primarily used in evidential discussions, ideas from full theodicies also appear in responses to the logical problem. The “soul-making” tradition, associated with thinkers like Irenaeus and modernly with John Hick, maintains that certain virtues—courage, compassion, forgiveness—can develop only in a world containing danger, suffering, and moral challenge.

If it is logically necessary that such goods require a world with some evils, then again the maxim “a good being removes every evil it can” must be revised. The logical problem’s strict incompatibility claim then becomes difficult to sustain.

Assessment and Contemporary Status

The status of the logical problem of evil in contemporary philosophy is widely regarded as controversial but largely diminished in influence relative to its evidential counterpart.

Many philosophers—including some who are non-theists—hold that the Free Will Defense and related arguments have succeeded in showing that there is no straightforward logical contradiction between the existence of evil and the traditional theistic God, once divine attributes and moral principles are stated with sufficient care. On this view, the original, strong logical problem of evil, as advanced by Mackie, does not go through as a demonstration of inconsistency.

However, critics maintain that:

• Some forms of horrific and seemingly “gratuitous” evil test the plausibility of claims that all such evils are logically tied to greater goods.
• Appeals to mere logical possibility set a very low bar; even if consistency is rescued, the probability of God’s existence in light of observed evil may still be low.
• Certain conceptions of God or goodness, especially highly traditional or scriptural ones, may still face internal tensions when confronted with the full range of suffering in the world.

As a result, much contemporary debate has shifted to the evidential problem of evil, which argues not for strict logical incompatibility but for a strong tension between the extent and nature of evil and the existence of God.

In summary, the logical problem of evil is a historically important and conceptually sharp argument, asking whether the traditional attributes of God can be consistently maintained alongside the reality of evil. While many philosophers now judge that the argument, in its strongest form, fails as a proof of inconsistency, it has played a major role in clarifying key concepts—especially divine omnipotence, moral goodness, and the nature of freedom—and continues to shape broader discussions of evil and theism.