What Is the Free Will Defense Against the Problem of Evil?

What Is the Defense?

The free will defense is a reply to the logical version of the problem of evil—the version that claims that the existence of evil is logically inconsistent with the existence of an all-good, all-powerful God. The defense argues that the two are consistent, because there's a possible reason God might have for permitting evil: the value of significantly free creatures. Significantly free creatures—creatures who can choose between good and evil, not just follow programming—are, on this view, a great good, worth the risk of evil. And such creatures require the possibility of evil: you can't have a creature free to choose good without the creature also being free to choose evil. So a world with free creatures and some evil might be better, from God's point of view, than a world without free creatures.

The defense was developed by Alvin Plantinga in The Nature of Necessity (1974) and God, Freedom, and Evil (1974). Plantinga was responding to J. L. Mackie's 1955 formulation of the logical problem, which had argued that the three claims (God is omnipotent, God is wholly good, evil exists) were jointly inconsistent unless the theist could show a morally sufficient reason God might have for permitting evil. Plantinga's defense supplies just such a possible reason. The defense's key move is to show that there's a possible world in which God, free creatures, and evil coexist, with God having a morally sufficient reason (the value of free will). If such a world is possible, the claims are logically consistent, and Mackie's argument fails.

The Distinction from a Theodicy

It's crucial to the defense that it's a defense, not a theodicy. A theodicy tries to identify God's actual reasons for permitting evil—to say why God, in fact, permits evil. A defense only tries to show that God and evil are logically consistent—to identify a possible reason God might have, whether or not it's the actual reason. The difference is in the modal status: a theodicy commits to what is the case; a defense commits only to what could be the case.

This distinction matters because the logical problem only needs the weaker reply. Mackie's argument was that the claims are inconsistent—that there's no possible way they could all be true. To defeat that, Plantinga only needs to show one possible way, not the actual way. So the defense is a more modest project than theodicy, and it's easier to carry off. The defense doesn't tell you why God permits evil; it tells you that the existence of evil doesn't, by itself, show that God doesn't exist.

The Transworld Depravity Move

The cleverest part of Plantinga's defense is the notion of transworld depravity, which handles a serious objection. The objection runs: even if God values free creatures, why didn't God create free creatures who always freely choose the good? A creature who is free but always chooses well is possible (or so it seems); God, being omnipotent, could create such creatures; so why the evil? If God could have made free creatures who never go wrong, then the free will move doesn't justify the actual evil.

Plantinga's reply is transworld depravity. The notion is technical, but the core idea is that a creature might be such that, in every feasible world (every world God could actualize, given the creature's free choices), the creature goes wrong in some way. The creature is free in each world, but in each world it freely chooses some evil. The creature "could have done otherwise" in each situation, but across all the worlds God could actualize, it always goes wrong somewhere. If a creature has transworld depravity, then God can't actualize a world in which that creature exists and never does evil, without compromising the creature's freedom. So God might be unable to create free creatures who always choose well, even though such creatures are possible in themselves—the feasibility constraint, given the creature's free choices, blocks it.

Transworld depravity is contested. Critics argue that it's ad hoc, that it stacks the deck by positing a defect in the creature that God could presumably fix, and that it makes the distribution of evil depend on a metaphysical curiosity that doesn't seem theologically motivated. Defenders reply that the notion is coherent and that the defense only needs possibility, not actuality. The SEP entry on the problem of evil treats the move as widely accepted among philosophers as having answered Mackie's logical version, while noting that it doesn't address the evidential version.

The Scope: Moral and Natural Evil

The free will defense handles moral evil—evil that results from human free choice—well. Murder, betrayal, cruelty, war can be traced to the misuse of creaturely freedom, and the value of free will can justify God's permission of them. But the defense's scope is contested when it comes to natural evil—disease, earthquake, animal suffering, natural disaster—which doesn't obviously result from human free choice.

Plantinga, in the defense, extended the free will move to natural evil by hypothesizing that natural evil might result from the free choices of non-human spirits (demons, fallen angels). This extends the free will defense to cover natural evil, but at the cost of a controversial theological assumption. Critics object that the demonic hypothesis is speculative and that it doesn't really fit the distribution of natural evil (why would demons cause animal suffering before humans existed?). Other theodicists handle natural evil with the soul-making theodicy or with appeals to the necessity of natural law. The free will defense, on its own, doesn't fully handle natural evil, and most philosophers treat it as a partial reply.

The Evidential Problem Remains

The free will defense answers the logical problem, but the evidential problem—developed by William Rowe and others—remains. The evidential version concedes that God and evil are logically consistent but argues that the amount and distribution of evil make God's existence improbable. The free will defense, by design, doesn't address this. It shows consistency, not probability. To answer the evidential problem, the theist needs a theodicy (which identifies actual reasons) or skeptical theism (which argues we can't judge God's reasons) or some other probabilistic reply.

This is why most contemporary philosophers treat the free will defense as a partial victory. It defeated Mackie's logical argument, which was a serious challenge, but it left Rowe's evidential argument standing. The current debate about evil is largely about the evidential version, and the free will defense is part of the background rather than the cutting edge. The SEP entry treats the defense as a settled point about the logical problem, with the action now elsewhere.

Why It Matters

The free will defense matters for several reasons. It's a model of philosophical precision: it took a powerful argument (Mackie's), identified exactly what was needed to answer it (a possible consistency), and supplied that with technical care. It showed that the problem of evil, contrary to Mackie, doesn't refute theism by itself—the logical version fails. And it clarified the distinction between showing consistency and identifying reasons, a distinction that structures all subsequent discussion of the problem.

The defense also matters for what it doesn't do. It doesn't explain evil; it doesn't comfort the sufferer; it doesn't show that God exists. It only removes one kind of objection. This modesty is a virtue in philosophy but a limitation in pastoral and existential contexts, where people want to know why God permits the evil they're suffering. The free will defense is a technical achievement in philosophy of religion, and its value is in clarifying what the problem of evil can and can't show.

Sources

• Stanford Encyclopedia of Philosophy, "The Problem of Evil" — https://plato.stanford.edu/entries/evil/
• Stanford Encyclopedia of Philosophy, "Philosophy of Religion" — https://plato.stanford.edu/entries/philosophy-religion/
• Stanford Encyclopedia of Philosophy, "Religious Epistemology" — https://plato.stanford.edu/entries/religious-epistemology/
• Stanford Encyclopedia of Philosophy, "Augustine" — https://plato.stanford.edu/entries/augustine/

Related Topics

• What Is the Problem of Evil? — the challenge the defense replies to.
• What Is a Theodicy? — the more ambitious project of identifying reasons.
• What Is the Soul-Making Theodicy? — Hick's reply to natural evil.
• What Is Natural Evil? — the harder half of the problem.
• Philosophy of Evil — the wider framework.