Original Sin
the fall · inherited sin
The Christian doctrine that human nature is wounded by inherited disorder transmitted from the fall of Adam, leaving the will divided against itself and unable consistently to will the good without grace.
In practice
The observation the doctrine starts from is ordinary: people regularly fail to do what they have decided to do, and the failure is not explained by ignorance.
The common mistake
Reading it as a claim about inherited guilt for someone else's act. The central claim concerns a damaged capacity rather than blame transferred across generations, though the two have often been run together.
For the good that I would I do not: but the evil which I would not, that I do.
Paul, in Romans 7, and the observation is ordinary enough that everybody has made it. People regularly fail to do what they have decided to do, and the failure is not explained by ignorance — they knew, they had resolved, and the resolution did not hold.
Augustine took that experience as the datum a doctrine had to explain, and original sin is the explanation.
The divided will
The analysis in Confessions VIII is the heart of it, and it is a piece of psychology before it is a piece of theology.
Augustine is trying to convert and cannot make himself do it. He notices something strange: when he commands his hand to move, it moves; when he commands his will to change, nothing happens. And the failure is not that something else is stopping him. He is the one refusing.
The will, he concludes, is not a single faculty that issues orders. It is divided against itself — willing and not willing at once, and the part that wills the good is not in charge. That is what he means by a wounded nature: the capacity for self-direction is damaged rather than absent.
Note what this is not. It is not the claim that people are wicked, and Augustine says so explicitly: fallen human beings retain real goods and do real goods. What they cannot do is order themselves consistently toward the good without help. The distinction is the difference between a broken instrument and a bad one.
For the same phenomenon described without the theology, see akrasia — weakness of will, which the Greeks treated as a puzzle about knowledge and Augustine treats as a fact about the will.
The hard part
If the condition is inherited rather than committed, in what sense is anybody answerable for it? An infant has done nothing.
The tradition produced three answers and none is comfortable.
Traducianism. The soul comes from the parents along with the body, so the damage comes with it. Tertullian held it. It makes transmission intelligible at the cost of a difficult account of what souls are.
Creationism. God creates each soul directly, into a nature already fallen. The standard Catholic position, held by Aquinas. It protects the soul's origin and makes the arrangement look harder to justify.
Federal headship. Adam acted as humanity's representative, so his act is imputed to those he represented. Reformed theology's answer. It is the cleanest legally and the most exposed to the objection that nobody appointed him.
Each is an attempt at the part of the doctrine that is hardest to state without making it unjust, and the difficulty is genuine rather than a failure of ingenuity.
Pelagius, and why he lost
Pelagius, a British monk teaching in Rome around 400, held the obvious alternative: human nature retains the full capacity for good, and difficulty is difficulty rather than incapacity. Grace helps; it is not required.
Augustine spent twenty years against this, and the position was condemned at Carthage in 418. The argument that carried was not primarily scriptural. It was that Pelagius could not account for the phenomenon — that the experience of knowing the good and reliably failing at it is not what a merely difficult task feels like.
The alternative keeps returning in every century, which suggests both that it is the natural thing to think and that something keeps making it hard to hold.
How far the damage goes
The Reformation pushed the doctrine to its limit. Luther's Bondage of the Will (1525) argues against Erasmus that the fallen will is enslaved rather than weakened — incapable of any movement toward the good on its own. Calvin systematized this as total depravity, which has been misread ever since as the claim that people are as bad as possible. It says something narrower: no part of human nature is untouched, which leaves plenty of room for ordinary decency.
Trent, in 1546, affirmed the reality of the condition against Pelagian softening while rejecting the strongest Protestant formulations, and that remains the Catholic position.
The whole dispute is downstream of one question — how much free will survives the damage — and every position on original sin is a position on that.
Concept web
Open the full webQuestions
What is original sin?
The Christian doctrine that human nature is damaged by an inherited disorder traced to the fall, leaving the will divided and unable to consistently choose the good without grace.
Who developed the doctrine?
Augustine gave it systematic form in the fifth century, against Pelagius, who held that people can choose rightly by their own power. Augustine's position became the Western standard.
What philosophical problems does it raise?
Chiefly how someone can be responsible for a condition they inherited rather than chose, and how that squares with the justice of the God said to judge them.