Problem of Evil — I can explain the problem of evil and distinguish logical vs evidential versions. - Philosophy

SECTION 1

Historical Context & Motivation

The problem of evil is arguably the oldest and most emotionally compelling challenge to theism—the belief that an omnipotent, omniscient, and omnibenevolent God exists. If such a God is all-powerful, all-knowing, and perfectly good, why does the world contain so much suffering? This tension has occupied thinkers from ancient Greece through the modern analytic tradition, generating a rich philosophical literature that remains central to the philosophy of religion. The problem is not merely academic; it touches the lived experience of anyone who has witnessed cruelty, natural disaster, or seemingly pointless suffering and wondered how this could be reconciled with a loving creator.

~300 BCE • Epicurus and the Epicurean Paradox

Epicurus articulates an early trilemma: if God is willing to prevent evil but not able, he is not omnipotent; if able but not willing, he is not benevolent; if both able and willing, why does evil exist? This formulation is preserved by Lactantius and becomes a foundational statement of the problem.

1710 • Leibniz Coins 'Theodicy'

Gottfried Wilhelm Leibniz publishes Théodicée, coining the term 'theodicy' (from Greek theos + dikē) and arguing that this is the 'best of all possible worlds.' His work frames evil as a necessary feature of the optimal cosmic design.

1779 • Hume's Dialogues

David Hume's posthumous Dialogues Concerning Natural Religion features the character Philo pressing the argument from evil against natural theology, emphasizing the sheer scale of animal and human suffering as evidence against a benevolent designer.

1955 • J.L. Mackie's Logical Argument

In 'Evil and Omnipotence,' J.L. Mackie formulates the logical problem of evil as a strict logical inconsistency: the existence of evil is logically incompatible with an omnipotent, omnibenevolent God. This paper crystallizes the 'logical version' of the problem.

1979 • William Rowe's Evidential Argument

William Rowe publishes 'The Problem of Evil and Some Varieties of Atheism,' shifting the debate from logical impossibility to probabilistic reasoning. He argues that gratuitous evil—suffering that serves no greater good—makes God's existence unlikely, inaugurating the 'evidential version' of the problem.

The historical trajectory reveals an important conceptual shift. Ancient and early modern thinkers typically posed the problem in all-or-nothing terms: evil's existence seems flatly contradictory to theism. By the late twentieth century, philosophers recognized that demonstrating a strict logical contradiction is extraordinarily difficult, and the debate evolved toward a more nuanced probabilistic framework. Understanding the difference between these two formulations—the logical problem of evil and the evidential problem of evil—is the central goal of this lesson.

SECTION 2

Core Principles & Definitions

Before examining the two versions of the problem, we need to establish several foundational concepts that structure the entire debate. These terms recur throughout the philosophy of religion and are essential for precision in argumentation.

Classical Theism's Three 'Omni' Properties

Classical theism holds that God is omnipotent (all-powerful), omniscient (all-knowing), and omnibenevolent (perfectly good). The problem of evil gains its force only if all three attributes are affirmed simultaneously.

Moral vs. Natural Evil

Moral evil results from the free choices of agents (murder, theft, cruelty). Natural evil arises from natural processes independent of human agency (earthquakes, disease, famine). Both types pose challenges for theism.

Theodicy vs. Defense

A theodicy attempts to explain why God actually permits evil (e.g., soul-making, free will). A defense merely shows that God's existence is logically compatible with evil, without claiming to know God's actual reasons.

Gratuitous vs. Justified Evil

Gratuitous evil is suffering that serves no greater good and could be prevented without loss of a compensating benefit. Justified evil is suffering that is a necessary condition for some outweighing good. This distinction is pivotal for the evidential argument.

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KEY TAKEAWAY

Think of the problem of evil like a stress test on a structural beam. The logical version asks whether the beam can hold any weight at all—is the structure of theism internally contradictory? The evidential version asks whether the beam can hold this much weight—given the actual quantity and distribution of suffering we observe, is theism a plausible explanation? Both are legitimate tests, but they require different standards of proof and invite different responses.

SECTION 3

Visual Explanation — The Structure of the Problem

The following diagram maps the logical structure of the problem of evil, showing how the three divine attributes interact with the existence of evil and how the two major formulations diverge. The left side represents the premises shared by both versions, while the right side shows the distinct conclusions each version draws.

Figure 1. The three divine attributes (top) converge on the shared inference that God would eliminate evil. The observation that evil exists then forks into two distinct conclusions: the logical version (left) claims a deductive contradiction, while the evidential version (right) claims a probabilistic inference against theism.

Notice that both versions share the same starting premises and the same empirical observation. The critical divergence occurs at the inferential step: the logical version treats the conjunction of God's existence and evil's existence as a formal contradiction, while the evidential version treats the amount, distribution, and apparent pointlessness of evil as probabilistic evidence against theism. This distinction matters enormously for what kind of response (defense or theodicy) is appropriate and what standard of success the theist must meet.

SECTION 4

How the Arguments Work — Formal Structure

The Logical Problem of Evil (Mackie's Formulation)

J.L. Mackie's argument proceeds as a deductive proof by contradiction. The claim is that the following set of propositions is logically inconsistent—that is, they cannot all be true simultaneously, much as the statements 'this shape is a square' and 'this shape has three sides' cannot both be true of the same object. The argument requires supplementary premises (sometimes called 'bridge principles') connecting the divine attributes to predictions about evil.

MACKIE'S INCONSISTENT SET

P1: God is omnipotent. P2: God is omnibenevolent. P3: Evil exists. B1: An omnipotent being can prevent all evil. B2: An omnibenevolent being would want to prevent all evil. ∴ P1 ∧ P2 ∧ B1 ∧ B2 → ¬P3

Since P3 is observably true, Mackie concludes that at least one of P1, P2, B1, or B2 must be false. If B1 and B2 are necessarily true (as Mackie contends), then either God is not omnipotent or not omnibenevolent—or God does not exist.

The crucial weakness of the logical argument lies in bridge premises B1 and B2. Alvin Plantinga's celebrated Free Will Defense (1974) challenges B1 by arguing that it is logically possible that God cannot create a world with free creatures who never choose evil. If this is even possibly true—not necessarily actually true—then the inconsistent set dissolves, because the deductive argument requires strict logical impossibility. Most contemporary philosophers of religion, including many atheists, regard the logical problem as effectively answered by the Free Will Defense.

The Evidential Problem of Evil (Rowe's Formulation)

William Rowe's argument does not claim a logical contradiction but rather an inductive inference. It shifts the burden from deductive proof to the best explanation of observed suffering. The argument depends on the concept of gratuitous evil—instances of suffering for which we can discern no morally sufficient reason.

ROWE'S EVIDENTIAL ARGUMENT

P1: There exist instances of intense suffering that an omnipotent, omniscient being could have prevented without losing some greater good or permitting some equally bad or worse evil. P2: An omniscient, wholly good being would prevent the occurrence of any intense suffering it could, unless it could not do so without thereby losing some greater good or permitting some equally bad or worse evil. ∴ C: An omniscient, wholly good, omnipotent being probably does not exist.

The conclusion is probabilistic, not deductive. Rowe's argument hinges on P1: the claim that gratuitous evil exists. If a theist can show that we have no good reason to affirm P1—perhaps because our cognitive limitations prevent us from perceiving God's reasons—then the argument is weakened.

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Key Distinction

The logical argument needs only the bare existence of any evil to generate a contradiction. The evidential argument focuses on the quantity, distribution, and apparent pointlessness of evil. This is why defeating the logical argument (via Plantinga) does not automatically defeat the evidential argument (via Rowe).

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Detailed Comparison — Logical vs. Evidential

The following diagram and table present a side-by-side comparison of the two versions, emphasizing their distinct logical structures, the kinds of evidence they invoke, and the types of theistic responses they elicit. Understanding these differences is essential for navigating contemporary debates in the philosophy of religion.

Figure 2. Side-by-side comparison of the logical and evidential versions across six dimensions: argument type, key claim, evil invoked, standard of success, primary theistic response, and current status in the literature.

Feature	Logical Version	Evidential Version
Originator	J.L. Mackie (1955)	William Rowe (1979)
Logical form	Deductive: if premises are true, conclusion must be true	Inductive: premises make conclusion probable, not certain
What the atheist must show	That the set {God exists, evil exists} is logically contradictory	That gratuitous evil exists and lowers the probability of God's existence
What the theist must show	A possible reason God might permit evil (mere logical possibility)	That we cannot justifiably infer gratuitous evil from our experience
Handles natural evil?	Less effectively—free will covers only moral evil	Yes—natural evil is a primary example of seemingly gratuitous suffering

Table 1. Key differences between the logical and evidential versions of the problem of evil.

SECTION 6

Worked Example — Analyzing an Argument

Consider the following passage from a hypothetical philosophy essay: 'A fawn is trapped in a forest fire and suffers horribly for days before dying. No human being is aware of this suffering. No good seems to come from it—it does not build character, teach a lesson, or serve any discernible purpose. Therefore, God does not exist.' Let us analyze which version of the problem of evil this argument invokes and evaluate its strength.

Classifying and Evaluating a Problem-of-Evil Argument

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Step 1 — Identify the Type of Evil

The fawn's suffering in a forest fire is a case of natural evil: it results from a natural process (fire) rather than human choice. Note that no moral agent caused the fire or the fawn's entrapment.

Classification: Natural evil
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Step 2 — Determine the Version of the Argument

The argument emphasizes that 'no good seems to come from it' and that the suffering is apparently purposeless. This focus on the absence of a morally sufficient reason signals the evidential version. A logical version would simply assert that any evil contradicts God's existence, without needing to emphasize pointlessness. This is, in fact, Rowe's own famous example of the fawn.

Version: Evidential (Rowe-style)
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Step 3 — Reconstruct the Premises

P1: There exist instances of intense suffering (the fawn) that an omnipotent, omniscient being could have prevented without thereby losing some greater good or permitting some evil equally bad or worse. P2: An omniscient, wholly good being would prevent any intense suffering it could unless doing so would lose a greater good. Conclusion: Therefore, it is probable that no omniscient, wholly good, omnipotent being exists.

Note: The conclusion says 'probable,' not 'certain'
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Step 4 — Evaluate the Argument's Vulnerability

The key vulnerability is P1. The skeptical theist (e.g., Stephen Wykstra) would argue that our inability to see a morally sufficient reason for the fawn's suffering does not entitle us to conclude that there is no such reason. Just as an infant cannot understand why a parent allows a painful vaccination, perhaps humans cannot comprehend the goods God might be securing through suffering. This response is called the 'noseeum' inference critique: the move from 'we can't see a reason' to 'there is no reason' is epistemically suspect.

Main theistic counter: Skeptical Theism
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Step 5 — Assess Overall Strength

The argument is stronger than the logical version because it does not require proving a strict impossibility—it only needs to establish that gratuitous evil is more probable than not. However, the skeptical theist response remains potent: if we have reason to think our cognitive capacities are limited relative to God's, then the probability assessment underlying P1 may be unreliable. The debate thus becomes partly an epistemological one about the scope and limits of human cognition.

Assessment: Strong but not decisive; the debate continues

SECTION 7

Major Theistic Responses — Strengths & Limitations

The problem of evil has generated a rich ecosystem of theistic responses. These range from full-blown theodicies (which claim to explain why God permits evil) to more modest defenses (which merely show logical or probabilistic compatibility). Each response has characteristic strengths and vulnerabilities, and understanding them is essential for evaluating the overall dialectic.

Response	Strengths	Limitations
Free Will Defense (Plantinga)	Successfully dissolves the logical problem. Only requires showing that it is possible God could not create free beings who never do evil. Philosophically elegant and widely accepted.	Does not address natural evil (earthquakes, disease). Only aims at logical possibility, not plausibility. Does not engage with the evidential problem.
Soul-Making Theodicy (Hick)	Provides a positive account of why suffering might be valuable: it enables moral growth, courage, compassion, and spiritual maturity. Addresses both moral and natural evil.	Struggles with extreme cases (infant suffering, animal pain). Seems to imply God instrumentalizes suffering. Requires that all suffering contributes to growth, which is empirically questionable.
Skeptical Theism (Wykstra, Alston)	Undermines the evidential argument at its epistemological root. Does not require specifying God's actual reasons—only showing that we should not expect to know them.	Risks excessive skepticism: if we cannot reason about God's purposes, can we make any moral judgments? Critics call this 'cognitive paralysis.' May undermine moral reasoning generally.
Greater Good Theodicy	Intuitive: evils are necessary conditions for outweighing goods (e.g., no courage without danger). Broad scope.	An omnipotent God might achieve the same goods without the corresponding evils. The 'necessity' claim requires defense.

Table 2. Major theistic responses to the problem of evil, with their characteristic strengths and limitations.

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KEY TAKEAWAY

Think of the theistic responses like different strategies a defense attorney might use. The Free Will Defense is like getting the case dismissed on a technicality—it shows no formal contradiction. Skeptical Theism is like arguing that the prosecution lacks sufficient evidence. Soul-Making is like presenting a positive alternative narrative. Each is effective in a different courtroom (i.e., against a different version of the argument), and a comprehensive theistic position typically draws on multiple strategies simultaneously.

SECTION 8

Connections to Advanced Theory

The problem of evil connects to several advanced topics in philosophy of religion, epistemology, and ethics. Understanding where this foundational debate leads prepares you for deeper engagement with the literature. The evidential problem, in particular, has spawned sophisticated Bayesian formulations that use formal probability theory to assess whether observed suffering counts as evidence against theism.

This Lesson (Foundational)	Advanced Development
Logical problem of evil (Mackie)	Modal logic formulations; transworld depravity (Plantinga); possible-worlds semantics for assessing compossibility of God and evil
Evidential problem of evil (Rowe)	Bayesian arguments from evil (Draper, 1989); comparing the likelihood of observed suffering under theism vs. naturalism using P(E\|T) vs. P(E\|N)
Skeptical theism	Epistemology of religious disagreement; CORNEA (Condition of Reasonable Epistemic Access, Wykstra); implications for moral skepticism
Moral vs. natural evil distinction	Evolutionary problem of evil (animal suffering over millions of years); the hiddenness of God (Schellenberg); problem of divine silence

Table 3. How foundational concepts in this lesson connect to advanced topics in philosophy of religion.

Paul Draper's Bayesian formulation deserves special mention. Draper argues that we should compare the probability of observed suffering given theism against its probability given the Hypothesis of Indifference (that the natural world is not the product of a benevolent agent). Since gratuitous suffering is far more expected on the Hypothesis of Indifference than on theism, the existence of such suffering constitutes strong Bayesian evidence against theism. This line of argument represents the cutting edge of the evidential problem and demonstrates how formal epistemological tools can be brought to bear on questions that were once treated as purely qualitative.

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Looking Ahead

If you continue in philosophy of religion, you will encounter closely related problems such as the problem of divine hiddenness (why doesn't God make his existence more obvious?) and the problem of hell (is eternal punishment compatible with perfect goodness?). Each of these can be understood as a specialized variant of the broader challenge that evil and suffering pose to theistic belief.

SECTION 9

Practice Problems

Question 1: CONCEPTUAL

Explain in your own words why the problem of evil only arises for classical theism (a God with all three 'omni' properties) rather than for a finite or morally indifferent deity.

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The problem of evil requires the conjunction of omnipotence, omniscience, and omnibenevolence. If God is not omnipotent, perhaps God lacks the power to prevent evil. If God is not omniscient, perhaps God is unaware of suffering. If God is not omnibenevolent, perhaps God is indifferent to suffering. Only when all three attributes are affirmed does the tension arise: a being that is able to prevent evil, knows about evil, and wants to prevent evil presumably would prevent evil. The existence of evil then demands explanation. A finite or morally neutral deity does not generate this expectation, so there is no 'problem' to solve.

Question 2: BASIC APPLICATION

Consider the following argument: 'An earthquake kills 50,000 people, including many innocent children. No one is morally responsible for the earthquake. Therefore, God and evil are logically incompatible.' Is this a logical or evidential version of the problem of evil? Justify your classification.

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Despite the dramatic example, the conclusion states that God and evil are 'logically incompatible,' which is the hallmark of the logical version. However, the argument's emphasis on the scale and innocence of the victims (rather than simply asserting that any evil creates a contradiction) suggests it is better read as an evidential argument poorly expressed in logical terms. A strict logical version needs only the bare existence of any evil, not a particularly horrifying case. The arguer seems to be relying on the emotional and evidential weight of extreme suffering to support the conclusion, which aligns more naturally with Rowe's evidential framework. This illustrates a common conflation that careful philosophical analysis should disentangle.

Question 3: INTERMEDIATE

Plantinga's Free Will Defense is widely regarded as successfully refuting the logical problem of evil. Explain why this same defense is insufficient as a response to the evidential problem of evil. Your answer should reference the different standards of proof required by each version.

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The Free Will Defense succeeds against the logical problem because it only needs to show that it is logically possible for God and evil to coexist—specifically, that God could not create free beings who never choose evil. Logical possibility is a very low bar: one need not demonstrate that this scenario is actual or even plausible, only that it involves no contradiction. The evidential problem, however, demands a higher standard. Rowe's argument concedes that God and evil might be logically compatible but contends that the specific quantity and distribution of evil (particularly natural evil and apparently gratuitous suffering) make God's existence improbable. The Free Will Defense does not address natural evil at all—earthquakes and diseases are not products of free will—and it does not explain why the amount of moral evil is so great. To counter the evidential argument, the theist needs either a theodicy that explains the actual pattern of suffering or an epistemological move (like skeptical theism) that undermines our confidence in identifying gratuitous evil.

Question 4: APPLIED

A student writes: 'The Holocaust proves that God does not exist, because no good could ever justify the murder of six million innocent people.' Analyze this claim. Which version of the problem of evil does it invoke? What are the strongest theistic and atheistic responses to it?

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This argument is best classified as an evidential argument. It does not merely assert a logical contradiction; rather, it appeals to a specific historical atrocity and claims that the magnitude of suffering is too great to be justified by any compensating good. The strongest atheistic support for this claim draws on Rowe's framework: the suffering of Holocaust victims appears gratuitous because we cannot identify a greater good that required it and that could not have been achieved otherwise. The strongest theistic responses include skeptical theism (our inability to identify the justifying good does not entail there is none—God's purposes may transcend our comprehension) and versions of the soul-making theodicy (the possibility of radical evil is a necessary condition for the existence of morally significant free will, which is itself a great good). Critics of the theistic responses note that skeptical theism risks trivializing historical atrocities, while the soul-making response seems obscene when applied to the actual suffering of innocent people. This example illustrates why the evidential problem remains the live battleground in contemporary philosophy of religion.

Question 5: CRITICAL THINKING

Evaluate the following claim: 'Skeptical theism, if taken seriously, undermines all human moral reasoning—because if we cannot know whether suffering serves a greater purpose, we have no grounds for preventing suffering ourselves.' Is this a decisive objection to skeptical theism, or can the skeptical theist respond? Construct arguments on both sides.

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This is the 'moral paralysis' objection to skeptical theism, and it is one of the most debated issues in contemporary philosophy of religion. On the critic's side: if we truly cannot assess whether any given instance of suffering is gratuitous, then we seemingly lose the epistemic basis for moral action. If the suffering of a child might serve an unknown divine purpose, should we hesitate before intervening? This conclusion is morally repugnant and practically absurd, which suggests that skeptical theism proves too much. On the skeptical theist's side: the scope of our epistemic humility is limited to evaluating God's cosmic-scale reasons, not to our everyday moral reasoning. We have direct moral obligations (revealed through conscience, scripture, or natural law) to prevent suffering when we can, regardless of whether that suffering might serve some unknown divine purpose. God's permission of evil and our obligation to prevent evil can coexist because God may intend for us to be the agents through whom evil is combatted. Furthermore, skeptical theism concerns an inference about God's reasons (a theoretical matter), whereas moral action concerns our duties (a practical matter). Keeping these domains separate allows the skeptical theist to maintain both epistemic humility about divine purposes and robust practical morality. The objection is serious but not obviously decisive, and the debate highlights deep connections between epistemology, ethics, and philosophy of religion.

SUMMARY

Summary

The problem of evil challenges classical theism by asking how an omnipotent, omniscient, and omnibenevolent God can coexist with suffering. The logical version (Mackie, 1955) claims a strict deductive contradiction between God's existence and any evil whatsoever. The evidential version (Rowe, 1979) argues inductively that gratuitous evil—suffering that serves no discernible greater good—makes God's existence improbable rather than impossible.

Plantinga's Free Will Defense is widely accepted as resolving the logical problem by showing the mere logical possibility that God and evil coexist. The evidential problem remains actively debated: skeptical theism questions our ability to identify gratuitous evil, while theodicies (soul-making, greater good) attempt to explain suffering positively. The distinction between moral evil and natural evil further complicates the debate, as natural evil resists free-will-based explanations. Mastering these distinctions equips you to engage critically with one of philosophy's most enduring and practically significant questions.