Peter Abelard (AD 1079–1142) served as professor of philosophy and theology at the University of Paris and was a notable scholastic theologian. Scholasticism is the discipline and method of bringing together philosophy and theology to make God and His ways understandable. In the medieval context, in which theology was "the queen of the sciences" and philosophy was employed as "the handmaid of theology," scholasticism addressed vexing questions such as "Are revelation and reason compatible or contradictory?" and "Can reason demonstrate what theology affirms about God?"
Abelard contributed significantly to the scholastic endeavor. In terms of its method, his most famous work, Sic et Non (Yes and No), developed the dialectical approach of offering arguments both pro and con for a given position. In Sic et Non, he juxtaposed passages from Scripture and the opinions of the early church fathers on both sides of 158 theological issues. Rather than offering a reconciliation of the conflicting positions, Abelard let the contradictions stand, allegedly to stimulate careful thinking. His opponents viewed the unresolved tension as indicative of his heretical views.
In terms of scholastic theological development, Abelard clashed with the traditional ransom theory of the atonement, which posited that Christ's death was a payment to Satan in order to liberate sinful people. He also dissented from the satisfaction theory of Anselm, which viewed Christ's death as a satisfaction offered to God, whose honor had been robbed by sin.
In their place, Abelard developed the "moral influence theory" of the atonement. In Abelard's words: "The purpose and cause of the incarnation was that [Christ] might illuminate the world by his wisdom and excite it to the love of himself." That is, Satan was not offered a ransom, nor did God demand Christ's death as a payment for sin; rather, people needed their love for God stimulated by a convincing exhibition of love on the part of Christ. He provided such a demonstration by His life and death, which was the crowning act of love. Abelard states:
Our redemption is that supreme love shown in our case by the passion of Christ which not only liberates from slavery to sin, but [also] wins for us the true liberty of the sons of God, so that we may fulfill all things from love rather than from fear.
Thus, the work of Christ was an exhibition of divine love, stimulating people to love God. Abelard wrote, "Kindled by so great a benefit of divine grace, charity [love] should not be afraid to endure anything for [Christ's] sake."
With his moral influence theory, Abelard did not minimize the death of Christ but detached it from any connection to the forgiveness of sins. Furthermore, he removed the atonement from an objective reality—what Christ accomplished on the cross for sinful people—to a subjective influence on them, prompting them to reciprocate this love. Abelard described the center of the Christian faith as this: "Christ died for us in order to show how great was his love for humanity and to prove that love is the essence of Christianity."
Abelard was also responsible for developments in scholastic eschatology. Specifically, he revised the doctrine of limbo infantium—the limbo of infants—that Augustine had articulated much earlier. Augustine believed that infants who were not baptized (and, therefore, not cleansed from original sin and not born again by the Holy Spirit through baptismal regeneration) could not enter the kingdom of heaven. Because these unbaptized infants had never personally sinned, said Augustine, they did not need "the remission of the sin which they have themselves committed in their life"; they lacked only forgiveness for original sin. Accordingly, Augustine posited that infants who die "without being baptized will be involved in the mildest condemnation of all."
Abelard dissented, denying that unbaptized infants experience any physical torment in hell. Instead, he affirmed that their only punishment is the pain of loss: they forfeit the beatific vision—the blessing of seeing God face to face in heaven. Pope Innocent III picked up Abelard's notion and stated that infants who die while unbaptized, and thus still characterized by original sin, suffer "no other pain, whether from [physical] fire or from the [prick] of conscience, other than the pain of being deprived forever of the vision of God." Thomas Aquinas, himself a scholastic theologian, would further modify the church's view of limbo infantium.
In summary, Abelard was a leading contributor to scholasticism both in its methodology and theological formulation.