A twelfth-century treatise on sin, consent, and the moral weight of intention
What the Work Is
Ethics, also known by its subtitle Scito te ipsum (“Know Yourself”), is a philosophical treatise written by Peter Abelard in 1138 or 1139, shortly after he completed a commentary on the Epistle to the Romans. The work was originally planned as a two-volume project, but Abelard set aside the second half—which would have addressed the nature of virtuous living—after writing only a single page. The subtitle was a popular motto among monastic writers of the period. Most surviving copies of the text date from the fourteenth and fifteenth centuries, though two of the earliest known manuscripts, from the twelfth century, are held in the Bavarian State Library.
What the Book Is About
The treatise offers a systematic account of sin, arguing that sin—understood as “scorn for God”—is fundamentally a matter of consent rather than deeds. Abelard develops this position in contrast to the prevailing penitential literature of his day, which tended to treat wrongful thoughts and wrongful actions as equally sinful. The Decretum of Burchard of Worms, for example, went so far as to suggest that merely planning to commit a wrongful act was indistinguishable from actually performing it. Such penitentials, however, gave little attention to the role of intention or motive. Abelard’s treatise is an attempt to correct this oversight by locating moral culpability in the inner act of consent.
Key Ideas and Themes
Abelard defines sin, or peccatum, as that which is worthy of God’s damnation and requires repentance. Yet he insists that the content of what he calls peccatum proprie—proper sin—is subjective. A person is guilty of scorn for God when they fail to do what they sincerely believe God requires, even if that belief is mistaken. This means that moral guilt is not determined by the objective rightness or wrongness of an action, but by the agent’s own conscience.
The central claim of the work is that proper sin resides in consensus, or consent, rather than in voluntas, the desire or will to act, and still less in the outward performance of the deed. Abelard explains that one consents to what is not allowed when one does not draw back from carrying it out and is entirely ready to do it should the opportunity arise. Desire, however, is not a necessary precondition for sin, since one can consent to sin unwillingly. He illustrates this with the example of a servant who, under duress, kills his bloodthirsty master in self-defence. The servant did not willingly consent to the killing, even though his consent arose from a certain will to live. Abelard draws a careful distinction here: willing to do something in order to achieve something else—willing to kill in order to live—is fundamentally different from willing to do that thing simply for its own sake. The former does not imply the latter. To avoid confusion, he suggests that what is said to be “willed” in such cases should more precisely be described as “endured.”
Abelard also introduces the notion of quod non convenit, or “unfitting” deeds prohibited by God. Building on his earlier point that actual sin arises from knowingly consenting to what one merely believes to be unfitting, he argues that one could commit truly unfitting deeds without sinning, depending on one’s intentio, or reasons for consent. This leads him to a striking conclusion: infidels who sincerely believe they are honouring God cannot, properly speaking, be guilty of sin, even if their actions and intentions are in fact not good. They have no contempt for God in what they do for God’s sake and on account of which they judge themselves to be acting well. Nevertheless, they remain liable to divine punishment, which is why Jesus cried out on the cross, “Father, forgive them; for they know not what they do.”
From this it follows that divine moral precepts such as the Ten Commandments relate fundamentally to one’s consent to external actions, not to the actions in and of themselves. In practice, consent appears to be synonymous with irresistible temptation: external actions are not within one’s control, but consent is. The less something is in our power, the less fitting it is to command it. Moreover, Abelard maintains that one’s standing before God is fixed once an individual has consented to an act, even if it were possible not to perform the act afterwards. Reconciliation with God, in his view, requires repentance, confession, and satisfaction through penance.
Structure and Approach
The treatise is a work of moral philosophy cast in a scholastic mode, proceeding by definition, distinction, and illustrative example. Abelard carefully delimits his terms—sin, consent, will, desire, intention—and tests his definitions against concrete cases, such as the servant who kills in self-defence. The argument is structured around the claim that consent, not action, is the locus of moral culpability, and Abelard develops this thesis by anticipating objections and refining his vocabulary accordingly. The work’s brevity and its abandoned second volume suggest that Abelard intended a larger project but chose to focus his attention on the foundational question of what makes an act sinful in the first place.
Significance and Influence
Abelard anticipated that his theory of sin would provoke criticism, noting that some would be upset to hear that the act of sin adds nothing to guilt or damnation before God. Indeed, in 1140, at the urging of Bernard of Clairvaux, the Council of Sens formally condemned Abelard for suggesting that actions in themselves were morally indifferent. Despite this censure, the ideas of the Ethics were echoed in many subsequent medieval treatises, including those of Richard of Saint Victor and Thomas Aquinas. The work thus stands as a pivotal moment in the history of moral thought, shifting the focus of ethical analysis from outward behaviour to the inner life of the agent—a move that would resonate through later Christian theology and beyond.
Abelard’s broader philosophical reputation provides additional context for the treatise’s arguments. He was celebrated for his logical solution to the problem of universals via nominalism and conceptualism, and he pioneered the focus on intent in ethics. He is often referred to as the “Descartes of the twelfth century” and is considered a forerunner of Rousseau, Kant, and Spinoza, with some crediting him as a chief forerunner of modern empiricism. In Catholic theology, he is best known for his development of the concept of limbo and his introduction of the moral influence theory of atonement, and he is considered, alongside Augustine, to be the most significant forerunner of later theological developments.
