The Influence of Dualism on Augustine’s Understanding of the Problem of Evil
Saint Augustine of Hippo (354–430 CE) spent nearly a decade as an adherent of Manichaeism, a religious movement that explained the existence of evil through a radical dualism of two co-eternal principles: a realm of Light (good) and a realm of Darkness (evil). This early exposure profoundly shaped his initial attempts to solve the problem of evil—namely, how an all-powerful and all-good God can permit evil to exist. Although Augustine ultimately rejected Manichaean dualism, its influence lingered in his language, psychology, and metaphysics for years. This essay traces that influence across his career, showing how he gradually replaced a cosmic conflict of substances with a Christian doctrine of evil as privatio boni (privation of good), original sin, and divine grace. The analysis draws on Augustine’s own reflections in his Retractationes (Reconsiderations), where he critiques and corrects his earlier statements.
Early Dualistic Traces in Augustine’s Thought
Augustine joined the Manichaeans as a young man in 373 CE and remained an auditor (a lower-level member) until 382 CE (Augustine, Confessiones 3.6.10–3.10.18). Manichaeism taught that evil is not merely the absence of good but a positive, substantial force. Light and Darkness are two independent realities locked in eternal combat; the material world results from their mixture. Evil, therefore, possesses its own “stuff” or substance.
Even after converting to Catholic Christianity in 386 CE, Augustine retained echoes of this view. In his 388 CE treatise De moribus ecclesiae catholicae et de moribus Manichaeorum (On the Customs of the Catholic Church and the Customs of the Manichaeans), he described evil as a “region” or “mass” (moles mali) (Augustine, De moribus ecclesiae catholicae et de moribus Manichaeorum 2.2.3). To a modern reader, this language suggests that evil occupies space or has weight; ideas that treat it almost like a second nature alongside the good. Augustine later recognized the danger: such phrasing could mislead readers into thinking evil has independent existence, reviving the very dualism he now opposed.
The Neo-Platonic Corrective: Evil as Privation
A decisive shift occurred in 384–385 CE when Augustine, living in Milan, read the works of the Neo-Platonic philosopher Plotinus (204–270 CE). Plotinus argued that evil is not a thing but the absence of being and goodness. Imagine a hole in a piece of cloth: the hole is real as damage, but it has no substance of its own; it is simply where the cloth is missing. Plotinus called this privatio boni—privation of good (Plotinus, Enneads 1.8.3–5).
Augustine adopted the concept eagerly. In Confessiones (Confessions), written 397–401 CE, he declares, “Evil has no positive nature; what we call evil is merely the lack of something that is good” (Augustine, Confessiones 7.12.18). The material world, far from being a prison built by Darkness, is God’s creation and therefore fundamentally good. Evil enters only when a free creature turns away from God, the source of all being, toward lesser goods. This turning-away creates a deficit, a privation.
Yet the transition was incomplete. Early dialogues such as De ordine (On Order, 386 CE) still portray the universe as a harmonious balance of opposites, where evil serves to highlight good—like shadows that make light visible. The metaphor recalls Manichaean equilibrium between Light and Darkness. In Retractationes 1.4.2, Augustine explicitly retracts the phrase “mass of evil,” insisting that “evil is not a substance” (Augustine, Retractationes 1.4.2).
Psychological Dualism: Body versus Soul
Manichaeism also taught that the human body belongs to the realm of Darkness and is therefore the primary source of sin. Augustine carried this suspicion into his Christian years. In Confessiones Book 8, he describes his inner struggle as a war between two wills: one pulling him toward God, the other dragging him toward sensual pleasure (Augustine, Confessiones 8.5.10–8.12.30). The language mirrors the old cosmic battle, now relocated inside the person.
Saint Paul’s Letter to the Romans, chapter 7, provided the breakthrough for Augustine. Paul writes, “I do not do the good I want, but the evil I do not want is what I do… It is no longer I that do it, but sin that dwells within me” (Rom 7:19–20 NRSV). For Augustine, sin is not identical with the body itself but a parasitic power that exploits the body’s appetites. The body is not evil; it is wounded by Adam’s fall. This historical event (Adam’s disobedience in Eden) replaces eternal cosmic warfare as the origin of evil.
Original Sin and the Collapse of Cosmic Dualism
By the late 390s, Augustine developed the doctrine of original sin. All humanity inherits both guilt (reatus) and a corrupted nature from Adam. The corruption spreads biologically through sexual generation, a process Augustine later called traducianism (the soul is transmitted along with the body from parents) (Augustine, De peccatorum meritis et remissione 1.9.9–1.10.11). Evil is no longer a rival substance but a hereditary defect, like a genetic disease passed from parent to child.
The implications are sweeping. The soul does not pre-exist in a higher realm and fall into matter (an idea Augustine briefly entertained under Platonic influence). Instead, every soul begins life already inclined toward self-love rather than God-love. The body is not the enemy; it is the battlefield where grace heals the wound.
Grace and the Final Overcoming of Dualism
The Pelagian controversy (412 CE onward) forced Augustine to clarify the role of grace. Pelagius, a British monk, taught that humans retain full freedom to choose good without divine help. Augustine countered that post-lapsarian (after the fall) human nature is enslaved to sin; the will is free to choose between evils but not to choose God without prior grace (Augustine, De spiritu et littera 3.5). Grace is not a reward for effort but an unmerited gift that restores the will’s capacity for good.
In De civitate Dei (The City of God), completed 413–426 CE, Augustine replaces the Manichaean two principles with the biblical two cities: the City of God (those who love God above all) and the City of Man (those who love self above all) (Augustine, De civitate Dei 14.28). The conflict is moral and historical, not metaphysical and eternal. God does not battle an equal opponent; He sovereignly permits evil to serve His redemptive plan. Predestination (God’s eternal choice to save some) ensures that grace triumphs.
Conclusion
Dualism died gradually in Augustine’s thought, not in a single dramatic conversion but through a series of intellectual surgeries—each removing a fragment of the old Manichaean tumor while grafting in healthier tissue from Scripture, philosophy, and personal experience. Neo-Platonic ontology performed the first excision, eliminating evil’s substance by redefining it as privatio boni. Think of it like a medical scan revealing that what appeared to be a second heart pumping darkness was actually a cavity where the heart’s rhythm had faltered. The cavity is real (it causes pain and dysfunction) but it is not a rival organ. It is a lack of proper function.
Pauline anthropology relocated the problem from the eternal cosmos to human history. The cosmic battlefield became a family inheritance: Adam’s single act of disobedience was like a cracked foundation in a house. Every subsequent generation builds on that flaw, inheriting warped beams and leaning walls. The structure stands, but it groans under the weight of its original defect. Evil is no longer an invading army from another realm; it is a structural weakness passed down through the bloodline.
Anti-Manichaean polemic acted as linguistic chemotherapy, purging dualistic rhetoric word by word. Augustine’s Retractationes reads like a surgeon’s log, meticulously noting where he once said “mass of evil” and replacing it with “privation of due order.” Language matters because metaphors shape thought. Calling evil a “region” risks imagining it with borders and citizens; calling it a “shadow” reminds us that shadows vanish when the light turns toward them.
Finally, the doctrine of grace transformed existential despair into theological hope. In Manichaeism, the war between Light and Darkness was a stalemate—human effort could only hope to liberate a few sparks of Light trapped in matter. Augustine’s mature view is more like a chess grandmaster playing against a child who keeps knocking over pieces. The child (humanity) is free to move, but every blunder serves the master’s strategy. Predestination is not fatalism; it is the assurance that the game ends with the board restored, every piece in its proper place. Grace is the hand that rights the toppled king.
What began as a cosmic war of Light and Darkness thus ended as a divine embrace that heals the privation within. Augustine’s mature theodicy retains the privatio boni (evil remains non-being) but subordinates it to a richer narrative: original sin explains why the privation exists, grace explains how it is overcome, and predestination explains why the outcome is certain. The shadow of Manichaeism lingers only as a cautionary silhouette on the wall, visible only when readers turn their backs to the light. Face the source, and the shadow dissolves. Augustine spent a lifetime learning to keep his gaze fixed there.