Ab'elard (Fr. Abélard or Abailard; Lat. Abælardus), PETER, the keenest thinker and boldest theologian of the 12th century, was born at Pallet or Palais, near Nantes, in 1079. Resigning his prospects as eldest son of a noble Breton house, he chose the career of a scholar. During the wanderings of his studenthood, he heard Roscellin, the champion of extreme Nominalism (q.v.), and was a pupil of William of Champeaux, one of the foremost of the Realist teachers. His singular gifts as a dialectician soon enabled him to encounter his master in debate, and he speedily met with brilliant success as a scholastic lecturer. In or about 1115 he became William's successor in the school of Notre-Dame; and for a few years he enjoyed a repute and influence such as few teachers have ever had. Amongst the pupils his teaching helped to mould were not a few of the greatest men of the age: Pope Celestine II., Peter Lombard, Berengar, and Arnold of Brescia. But Abelard's fall from prosperity and power was sudden and rapid. Within the precincts of Notre-Dame lived Héloïse, the niece of the canon Fulbert, then seventeen years of age, and already remarkable for her beauty and accomplishments. She soon kindled in the breast of Abelard, then thirty-eight years old, an overwhelming passion, which was returned by Héloïse with no less fervour. By the uncle's choice, Abelard became Héloïse's tutor and an inmate of the same house, and the lovers were happy together until Abelard's glowing love songs reached the ears of the canon. He sought to separate the lovers; but it was too late. They fled together to Brittany, where Héloïse bore a son, and was privately married to Abelard with the consent of her uncle. Not long after, Héloïse returned to Fulbert's house, and with singular self-devotion denied the marriage, that her love might be no hindrance to Abelard's advancement in the church. When shortly after Héloïse fled to the convent of Argenteuil, Fulbert, enraged at her husband's connivance, caused him to be brutally mutilated, so that he might be made canonically incapable of ecclesiastical preferment. In deep humiliation, Abelard entered the abbey of St Denis as monk; Héloïse took the veil at Argenteuil. Ere long a synod at Soissons (1121) condemned his teaching on the Trinity as heretical, and ordered him to be confined for a time.
In the hermit's hut at Nogent-sur-Seine, to which he retired, Abelard was soon again besieged by importunate disciples; the hermitage became a monastic school known as Paraclete, which, when Abelard was invited to become abbot of St Gildas-de-Rhuys in Brittany, was given to Héloïse and a sisterhood under her care. In his abbey Abelard maintained for ten years a struggle with disorderly and unfriendly monks, and at last fled from the hopeless task. Freed from his charge by the pope, he now devoted himself to the revision of all his works. When he ventured again to appear in public as a teacher, his theological adversaries, headed by Bernard of Clairvaux (q.v.), accused him of numerous heresies, of which he was found guilty by a council at Sens and by the pope. On his way to Rome to defend himself he died, reconciled ere death to his opponents, and absolved by the pope, at the priory of St Marcel, near Chalon, 21st April 1142. His remains were given into the keeping of Héloïse, whose own were twenty years afterwards laid beside them. From Paraclete, the ashes of both were taken to Paris in 1800, and in 1817 were buried in one sepulchre at Père la Chaise, where still they lie.—Abelard did more than any other to develop and fix that method of joint philosophising and theologising which was characteristic of the great Scholastics (q.v.); it was Abelard who made Aristotle the almost exclusive basis of theological dialectics. In the question of the universals (see NOMINALISM), he took a place between the extreme Nominalists and the thoroughgoing Realists. In opposition not merely to the unreasoning devotion of Bernard and the mystics, but as against the systematic dogmatism of Anselm, he taught that only that faith is well assured which is founded on reason. 'Understand that thou mayest believe' was his motto, not 'Believe that thou mayest understand.' His ethical system he set down in the work Nosce teipsum. Sic et Non is a curious collection of direct contradictions on important points gathered from the Fathers.
See monographs by Rémusat (Paris, 1845), Carrière (Giessen, 1853), Wilkens (Göttingen, 1855), Sauerland (Frankf. 1879), Deutsch (Leip. 1883), and Compayré (trans. 1893). The story of his life forms the subject of a remarkable drama by Rémusat; and the still extant correspondence between Abelard and Héloïse suggested to Pope his Epistle of Eloïsa to Abelard. The best collective edition of Abelard's works is by Cousin (2 vols. 1849-59).