Free will defense

The free will defense is the most influential theistic response to the logical problem of evil. Developed by Alvin Plantinga across three works — God and Other Minds (1967), “The Free Will Defence” (1965), and its definitive formulation in The Nature of Necessity and God, Freedom, and Evil (both 1974) — it argues that the existence of an omnipotent, omniscient, perfectly good God is logically compatible with the existence of evil. The defense does not claim to explain why God permits evil but only that it is logically possible for God to have morally sufficient reasons for doing so. If such a scenario is merely possible, the alleged logical contradiction between God and evil dissolves. This article examines the argument’s structure, its key concepts, the major objections it has faced, and its reception in contemporary philosophy of religion.^{1, 6}

The logical problem of evil

The free will defense responds to the logical problem of evil as formulated by J. L. Mackie in his 1955 paper “Evil and Omnipotence.” Mackie argued that three propositions central to traditional theism form a logically inconsistent set: (1) God is omnipotent, (2) God is perfectly good, and (3) evil exists. With the addition of two “quasi-logical rules” — that a good being eliminates evil as far as it can, and that an omnipotent being faces no limits on what it can do — Mackie contended that the theist holds beliefs that are not merely improbable but formally contradictory.³

Mackie considered and rejected the free will response in its pre-Plantinga forms. He argued that an omnipotent God could have created beings who always freely choose the good. If God is truly omnipotent, nothing prevents God from creating a world with free creatures who never sin. The fact that God did not do so, while having the power to do so, is incompatible with perfect goodness. This challenge — whether omnipotence extends to determining the outcomes of free choices — became the central issue that Plantinga’s defense addressed.³

Plantinga’s defense

Plantinga’s strategy is defensive rather than explanatory. A theodicy attempts to provide the actual reason God permits evil. A defense aims only to show that the theist’s beliefs are logically consistent — that there is some possible state of affairs in which God and evil coexist without contradiction. The defense succeeds if it identifies even one logically possible scenario that, if true, would render God and evil compatible. It does not need to show that the scenario is actual, probable, or even plausible — only that it is coherent.^{1, 6}

The defense proceeds in stages. Plantinga first argues that it is logically possible that God could not have created a world containing moral good without also containing moral evil. The argument rests on the premise that a world with creatures who possess genuine libertarian free will — the ability to choose between alternatives that is not causally determined by prior states — is more valuable than a world of automata who always do what is right but whose actions are determined by God. If this is so, then God’s creating a world with free creatures is justified even though such creatures might misuse their freedom.¹

But Mackie’s challenge goes deeper: why could God not create beings who are free yet always happen to choose the good? Plantinga’s answer requires two technical concepts: possible worlds and counterfactuals of creaturely freedom.²

Possible worlds and counterfactuals of freedom

A possible world, in Plantinga’s framework, is a maximal, consistent state of affairs — a complete way things could be. The actual world is one possible world among many. God, being omnipotent, can actualize any possible world — but with a crucial qualification. If a possible world includes creatures with libertarian free will, then the truth about what those creatures would freely do in any given circumstance is not up to God. These truths are called counterfactuals of creaturely freedom: propositions of the form “If creature C were in circumstances S, C would freely do A.”²

On Plantinga’s view, these counterfactuals are true prior to God’s creative act and are not within God’s control. God can decide which creatures to create and which circumstances to place them in, but God cannot determine what free creatures would freely do in those circumstances. This is not a limitation on God’s power but a logical consequence of what it means for a choice to be free in the libertarian sense. Asking God to determine the outcome of a free choice is like asking God to create a married bachelor — it is not a coherent task, and inability to perform incoherent tasks is not a limitation on omnipotence.^{1, 2}

This framework means that there is a distinction between possible worlds and feasible worlds. A world is possible if it involves no logical contradiction. A world is feasible for God if, given the true counterfactuals of creaturely freedom, God can actualize it. Some logically possible worlds — including worlds where free creatures always choose rightly — may not be feasible for God because the creatures God could create would not freely cooperate.^{2, 11}

Transworld depravity

The core of the free will defense is the concept of transworld depravity. A creature suffers from transworld depravity if, in every feasible world where that creature exists and is significantly free, there is at least one occasion on which the creature freely chooses wrongly. “Significantly free” means that the creature faces at least one choice between a morally right and a morally wrong action. Plantinga argues that it is logically possible that every creatable creature — every possible being with libertarian free will — suffers from transworld depravity.²

If universal transworld depravity obtains, then no feasible world contains free creatures who always do right. God faces a choice: create a world with free creatures who sometimes do wrong (and thereby permit moral evil) or create a world without free creatures (and thereby forfeit the goods that come with genuine moral agency). On this scenario, God cannot create a world containing both moral good and no moral evil. The logical problem of evil dissolves because Mackie’s additional premise — that an omnipotent being can create free creatures who never do wrong — is not a necessary truth. It is possibly false, and that logical possibility is all the defense requires.^{1, 2}

P1. It is logically possible that every creatable free creature suffers from transworld depravity.

P2. If P1, then it is logically possible that God cannot create a world with moral good but no moral evil.

P3. If P2, then the existence of an omnipotent, omniscient, perfectly good God is logically compatible with the existence of moral evil.

C. The existence of God is logically compatible with the existence of moral evil.

Extension to natural evil

The free will defense in its basic form addresses moral evil — evil resulting from the free choices of agents. Natural evil (earthquakes, diseases, animal suffering) presents a separate challenge, since it appears to result from impersonal natural processes rather than creaturely choices. Plantinga extended the defense by suggesting that it is logically possible that natural evil is caused by the free actions of non-human agents — Satan and other fallen angels — whose rebellion against God disrupted the natural order.¹

This extension is widely regarded as the weakest element of the defense. Critics note that it strains credibility to attribute tsunamis, genetic diseases, and millions of years of animal suffering to demonic free will. Plantinga himself acknowledges that this part of the argument is less compelling than the core defense, but maintains that the logical point stands: the scenario need only be logically possible, not plausible. Since a defense requires only logical possibility and not probability, even an unlikely scenario involving non-human free agents suffices to block the alleged contradiction.^{1, 6}

Other philosophers have developed alternative approaches to natural evil that do not invoke non-human agents. John Hick’s soul-making theodicy argues that natural evil is necessary for the kind of moral and spiritual development that constitutes the purpose of human life. Richard Swinburne argues that regular natural laws — including those that produce natural disasters — are necessary conditions for meaningful moral agency. These approaches function as theodicies rather than defenses, since they claim to identify the actual reason for natural evil rather than merely a logically possible one.^{9, 8}

Objections

The possibility of universal transworld depravity

The defense depends on the claim that it is logically possible that every creatable free creature suffers from transworld depravity. Critics have questioned whether this is genuinely possible. If the number of possible free creatures is infinite, the probability that every one of them suffers from transworld depravity may be vanishingly small. Otte has argued that transworld depravity for every possible creature requires an implausible coincidence in the counterfactuals of freedom — it would mean that across every possible free creature and every possible set of circumstances, not a single creature would freely cooperate with God’s purposes in every case. However, Plantinga’s defense does not require that universal transworld depravity is probable, only that it is logically possible. Whether it strains credulity is a separate question from whether it is coherent.^{10, 2}

The status of counterfactuals of freedom

The defense relies on there being true counterfactuals of creaturely freedom — facts about what free creatures would do in hypothetical circumstances. This assumption is central to Molinism, the view (named after the sixteenth-century Jesuit Luis de Molina) that God possesses “middle knowledge” of such counterfactuals. Critics have challenged whether counterfactuals of freedom can be true at all. If a creature’s choice is genuinely free in the libertarian sense, what grounds the truth of the claim about what the creature would do? The “grounding objection” contends that there is no fact of the matter about what a libertarianly free agent would do in a merely hypothetical situation, since nothing determines the outcome.^{14, 11}

Hasker has argued that if counterfactuals of freedom lack truth values, Plantinga’s defense fails because its central concept — transworld depravity — is defined in terms of such counterfactuals. However, defenders respond that the grounding objection, if successful, equally undermines the logical problem of evil: Mackie’s claim that God could have created free beings who always choose rightly also presupposes facts about what free creatures would do in various circumstances.¹⁴

Compatibilism and the value of free will

The defense assumes that the morally relevant kind of freedom is libertarian — that free choices are not causally determined. If compatibilism is true — if free will is compatible with determinism — then God could have determined that free creatures always choose rightly without compromising their freedom. On compatibilist assumptions, Mackie’s original challenge stands: God could have created free creatures whose choices are determined to be good, and the existence of moral evil is gratuitous. Plantinga acknowledges this and argues that libertarian free will is the kind that matters for the defense. Whether libertarian free will is coherent or even possible is itself a contested philosophical question.^{15, 3}

Mackie pressed this objection in The Miracle of Theism (1982), arguing that Plantinga’s defense presupposes a controversial metaphysical position on the nature of free will. If compatibilism is correct, the logical problem of evil remains unresolved. Mackie’s concession that the defense succeeds was therefore conditional: it succeeds if libertarian free will is possible, but that assumption is itself debatable.⁴

The amount of evil

Even if the defense shows that some moral evil is compatible with God’s existence, it does not explain the amount and distribution of evil in the actual world. Oppy argues that the defense addresses only the bare logical compatibility of God and evil but does nothing to address the evidential force of the world’s actual suffering. A world with one small lie would satisfy the requirements of transworld depravity, yet the actual world contains genocide, torture, and the suffering of children. The defense is silent on why the actual world contains so much evil rather than the minimum logically required by creaturely freedom.¹³

Reception and significance

The free will defense is widely regarded as one of the most significant achievements in twentieth-century philosophy of religion. Its reception has been remarkably broad. Mackie conceded in 1982 that the logical problem of evil is not “decisive” against theism, acknowledging that Plantinga had shown the three propositions in his inconsistent triad are not, after all, logically incompatible. William Rowe, the most influential proponent of the evidential problem of evil, accepted the defense’s success against the logical problem while developing his own evidential challenge as an alternative. The Stanford Encyclopedia of Philosophy summarizes the consensus: “it is now widely agreed that the logical argument from evil has been adequately answered.”^{4, 5, 6}

The defense’s significance lies not in resolving the problem of evil but in refining it. By showing that the logical formulation fails, Plantinga shifted the debate to the evidential formulation: not whether God and evil are logically incompatible, but whether the actual quantity, distribution, and types of evil make God’s existence improbable. This shift has structured the entire subsequent discussion. Rowe’s evidential argument (1979), the development of skeptical theism, and the focus on horrendous evils all presuppose that the logical problem has been resolved and that the real challenge lies elsewhere.^{5, 8}

Responses to the logical problem of evil⁶

Defense versus theodicy

A central methodological distinction in the literature is between a defense and a theodicy. A theodicy claims to identify the actual reason God permits evil — it is a positive account of divine purposes. A defense claims only that it is logically possible for God and evil to coexist — it is a negative refutation of the alleged contradiction. Plantinga insisted that his argument is a defense, not a theodicy. He does not claim to know why God permits evil, and he does not claim that transworld depravity is actual. He claims only that the scenario is logically possible, and that this possibility suffices to defeat Mackie’s argument.^{1, 12}

This distinction matters because it determines the standard of success. A theodicy must be plausible, well-evidenced, and morally satisfactory. A defense must be merely coherent. Many objections to Plantinga — that transworld depravity is implausible, that the fallen-angel hypothesis is far-fetched, that the defense does not address the amount of evil — are objections to it as a theodicy. As a defense, it need only clear the low bar of logical possibility. The debate over the problem of evil has accordingly moved beyond the question of logical consistency to questions of probability and evidence, where the standards are higher and the issues more contested.^{6, 8}

Contemporary developments

Plantinga’s defense has generated a substantial secondary literature. Van Inwagen has developed an independent defense that does not rely on counterfactuals of freedom: he argues that it is logically possible that God permits evil in order to bring about a world in which free creatures achieve reconciliation with God through a process that requires exposure to real evil. This “expanded defense” combines elements of Plantinga’s free will argument with aspects of Hick’s soul-making theodicy but maintains the modest logical aims of a defense rather than a theodicy.^{15, 8}

Flint has explored the defense’s relationship to Molinism more fully, arguing that if God possesses middle knowledge — knowledge of what every possible free creature would do in every possible circumstance — then God’s creative options are constrained by the counterfactuals of freedom in precisely the way Plantinga describes. On this view, the distinction between possible and feasible worlds is a natural consequence of divine middle knowledge, and transworld depravity is one among many constraints that might limit God’s creative options.¹¹

The free will defense remains a landmark in analytic philosophy of religion — not because it resolves the problem of evil, but because it establishes the logical terrain on which the contemporary debate takes place. By demonstrating that the oldest philosophical challenge to theism is not, in its strongest form, logically decisive, the defense has ensured that the philosophical discussion of God and evil continues to focus on questions of evidence, probability, and the moral adequacy of theistic responses to suffering.⁶