Anselm was a philosophical theologian and archbishop of Canterbury who is often dubbed the Father of Scholasticism. Scholasticism is the system of education that characterized schools and universities during the High Middle Ages (12th–14th century) and that aimed principally at reconciling and ordering the numerous and divergent components of an ever-growing body of knowledge with dialectic (logic or reason).

Anselm is best known for making several major contributions to early Scholastic theology, namely, his distinctive method of “faith seeking understanding,” his ontological argument for the existence of God, and his classic formulation of atonement theory.

Anselm was born into a wealthy family in Aosta in northern Italy. After his mother’s death in 1056 he left home, crossed the Alps into France, and in 1059 entered the Benedictine abbey school at Bec in Normandy, where Lanfranc taught him. In 1063 Anselm succeeded Lanfranc as prior and was consecrated abbot in 1078.

Toward the end of his priorate Anselm produced two significant works: the Monologion (Monologue on Reasons for the Faith; 1076) and the Proslogion (Address [to God], first titled Faith Seeking Understanding; 1077–78). Although both works are intensely contemplative, Anselm proposes philosophical or rational proofs for God’s existence.

In both works he begins with the first article of the Christian faith—namely, that God exists—and then seeks to understand it by reason (without further recourse to scriptural or traditional authorities). The basic argument of the Monologion, later called the “ontological argument,” runs thus: God is that being than which nothing greater can be thought. Yet “that than which nothing greater can be thought” cannot exist only in human thought or understanding.

Rather by definition, “that than which nothing greater can be thought” must also exist in reality. Hence God necessarily exists in reality. In the centuries after his death, Anselm’s method of “faith seeking understanding” (fides quaerens intellectum) became the basic model of inquiry into the divine and remains the classic definition of theology.

During his abbacy at Bec (1078–93), Anselm produced the treatises On Grammar, On Truth, On Free Will, and On the Fall of the Devil. As archbishop of Canterbury (1093–1109), Anselm composed several apologetic works, including his greatest theological treatise, Why God Became Man (or Why the God-Man; 1097–98), On the Virginal Conception and Original Sin (1099–1100), and On the Sacraments of the Church (1106–07).

In Why God Became Man, Anselm presents “necessary reasons” for the Incarnation. He argues that God had to become human in order for humankind to be saved because the first sin offended God’s honor infinitely, yet the guilty party (humanity) is finite. Even if they gave their entire lives to God, humans could not thereby pay the penalty for sin because even prior to sin they owed everything to their Creator.

Although humans are obliged to make satisfaction, then, only God (who is not a creature and therefore owes nothing) is actually able to do so—hence the God-man. Anselm’s treatise, which rejected the widely held ransom theory, made the most significant contribution to atonement theology in the Middle Ages.

During Lent in 1109 Anselm became seriously ill and died on Wednesday of Holy Week, April 21, 1109. His cult became firmly established in the Late Middle Ages, and his feast day continues to be celebrated on April 21. In 1720 Pope Clement XI declared Anselm a Doctor of the Church.