He was born at Pallet or Palais, not far from Nantes, in France, the eldest son of a noble Breton family. The name Abaelardus (also written Abailardus, Abaielardus, and in many other ways) is said to be a corruption of Habelardus, substituted by Abelard himself for a nickname ('Bajolardus') given him when a student. As a boy, he learned quickly, and, choosing an academic life instead of the military career usual for one of his birth, acquired the art of dialectic, the contemporary name for philosophy, meaning at that time chiefly the logic of Aristotle transmitted through Latin channels; this was the great subject of liberal study in the episcopal schools. Roscellinus, the famous canon of Compiegne, claims to have been his teacher; but whether this was in early youth, when he wandered from school to school for instruction and exercise, or some years later, after he had already begun to teach, remains uncertain.
Abelard's travels finally brought him to Paris while still in his teens. There, in the great cathedral school of Notre-Dame de Paris, he was taught for a while by William of Champeaux, the disciple of St Anselm and most advanced of Realists. He was soon able to defeat the master in argument, resulting in a long duel that ended in the downfall of the philosophic theory of Realism, till then dominant in the early Middle Ages, in favour of Nominalism. First, against opposition from the metropolitan teacher, while yet only twenty-two, Abelard set up a school of his own at Melun, then, for more direct competition, he moved to Corbeil, nearer Paris.
The success of his teaching was notable, though for a time he had to give it up, the strain proving too great for his constitution. On his return, after 1108, he found William lecturing in a monastic retreat outside the city, and there they once again became rivals. Abelard was once more victorious, and now stood supreme. William was only temporarily able to prevent him from lecturing in Paris. From Melun, where he had resumed teaching, Abelard went on to the capital, and set up his school on the heights of Montagne Sainte-Geneviève, overlooking Notre-Dame. From his success in dialectic, he next turned to theology and attended the lectures of Anselm at Laon. His triumph was complete; the pupil was able to give lectures, without previous training or special study, which were acknowledged superior to those of the master. Abelard was now at the height of his fame. He stepped into the chair at Notre-Dame, being also nominated canon, about the year 1115.
Distinguished in figure and manners, Abelard was seen surrounded by crowds - it is said thousands of students, drawn from all countries by the fame of his teaching. Enriched by the offerings of his pupils, and entertained with universal admiration, he came, as he says, to think himself the only philosopher in the world. But a change in his fortunes was at hand. In his devotion to science, he had always lived a very regular life, enlivened only by philosophical debate: now, at the height of his fame, he encountered romance.
Living within the precincts of Notre-Dame, under the care of her uncle, the canon Fulbert, was a girl named Heloise, of noble birth, and born about 1101. She is said to have been beautiful, but still more remarkable for her knowledge, which extended beyond Latin, it is said, to Greek and Hebrew. Abelard fell in love with her; and he sought and gained a place in Fulbert's house. Becoming tutor to the girl, he used his power for the purpose of seduction, and she returned his devotion. Their relations interfered with his public work, and were not kept a secret by Abelard himself. Soon everyone knew except the trusting Fulbert. When he found out, they were separated, only to meet in secret. Heloise became pregnant, and was carried off by her lover to Brittany, where she gave birth to a son. To appease her furious uncle, Abelard proposed a secret marriage, in order not to mar his prospects of advancement in the church; but Heloise opposed the idea. She appealed to him not to sacrifice the independence of his life, but reluctantly gave in to pressure. The secret of the marriage was not kept by Fulbert; and when Heloise boldly denied it, life was made so difficult for her that she sought refuge in the convent of Argenteuil.
Immediately Fulbert, believing that her husband, who had helped her run away, wanted to be rid of her, plotted revenge. He and some others broke into Abelard's chamber by night, and castrated him. The priesthood and ecclesiastical office were canonically closed to him. Heloise, not yet twenty, consummated her work of self-sacrifice and became a nun. It was in the abbey of Saint-Denis that Abelard, now aged forty, sought to bury himself with his woes out of sight. Finding no respite in the cloister, and having gradually turned again to study, he gave in to urgent entreaties, and reopened his school at the priory of Maisonceile (1120). His lectures, now framed in a devotional spirit, were once again heard by crowds of students, and all his old influence seemed to have returned; but he still had many enemies. No sooner had he published his theological lectures (apparently the Introductio ad Theologiam that has come down to us) than his adversaries picked up on his rationalistic interpretation of the Trinitarian dogma. Charging him with the heresy of Sabellius in a provincial synod held at Soissons in 1121, they obtained an official condemnation of his teaching, and he was made to burn his book before being shut up in the convent of St Medard at Soissons. It was the bitterest possible experience that could befall him. The life in his own monastery proved no more congenial than formerly. For this Abelard himself was partly responsible. He took a sort of malicious pleasure in irritating the monks. Quasijocando, he cited Bede to prove that Dionysius the Areopagite had been Bishop of Corinth, while they relied upon the statement of the Abbot Hilduin that he had been Bishop of Athens. When this historical heresy led to the inevitable persecution, Abelard wrote a letter to the Abbot Adam in which he preferred to the authority of Bede that of Eusebius of Caesarea's Historia Ecelesiastica and St Jerome, according to whom Dionysius, Bishop of Corinth, was distinct from Dionysius the Areopagite, bishop of Athens and founder of the abbey, though, in deference to Bede, he suggested that the Areopagite might also have been bishop of Corinth. Life in the monastery was intolerable for Abelard, and he was finally allowed to leave. In a desert place near Nogent-sur-Seine, he built himself a cabin of stubble and reeds, and turned hermit. When his retreat becoming known, students flocked from Paris, and covered the wilderness around him with their tents and huts. When he began to teach again he found consolation, and in gratitude he consecrated the new Oratory of the Paraclete.
Abelard, fearing new persecution, left the Oratory to find another refuge, accepting an invitation to preside over the abbey of Saint-Gildas-de-Rhuys, on the far-off shore of Lower Brittany. The region was inhospitable, the domain a prey to outlaws, the house itself savage and disorderly. Yet for nearly ten years he continued to struggle with fate before he left. The misery of those years was lightened because he had been able, on the breaking up of Heloise's convent at Argenteuil, to establish her as head of a new religious house at the deserted Paraclete, and in the capacity of spiritual director he often was called to revisit the spot thus made doubly dear to him. All this time Heloise had lived respectably. Living on for some time apart (we do not know exactly where), after his flight from the Abbey of St Gildas, Abelard wrote, among other things, his famous Historia Calamitatum, and thus moved her to write her first Letter, which remains an unsurpassed utterance of human passion and womanly devotion; the first being followed by the two other Letters, in which she finally accepted the part of resignation which, now as a brother to a sister, Abelard commended to her. He soon returned to the site of his early triumphs lecturing on Mount St Genevieve in 1136 (when he was heard by John of Salisbury), but it was only for a brief time: a last great trial awaited him. As far back as the Paraclete days, his chief enemy had been Bernard of Clairvaux, in whom was incarnated the principle of fervent and unhesitating faith, from which rational inquiry like Abelard's was sheer revolt, and now the uncompromising Bernard was moving to crush the growing evil in the person of the boldest offender. After preliminary negotiations, in which Bernard was roused by Abelard's steadfastness to put forth all his strength, a council met at Sens (1141), before which Abelard, formally arraigned upon a number of heretical charges, was prepared to plead his cause. When, however, Bernard had opened the case, suddenly Abelard appealed to Rome. Bernard, who had power, notwithstanding, to get a condemnation passed at the council, did not rest a moment till a second condemnation was procured at Rome in the following year. Meanwhile, on his way there to urge his plea in person, Abelard collapsed at the abbey of Cluny, and there he lingered only a few months before the approach of death. Removed by friend, for the relief of his sufferings, to the priory of St Marcel, near Chalon-sur-Saone, he died. First buried at St Marcel, his remains were soon carried off secretly to the Paraclete, and given over to the loving care of Heloise, who in time came herself to rest beside them (1164). The bones of the pair were moved more than once afterwards, but they were miraculously preserved even through the vicissitudes of the French Revolution, and now lie in the well-known tomb in the cemetery of Pere Lachaise at Paris.
Abelard was an enormous influence on his contemporaries and the course of medieval thought, but he has been known in modern times mainly for his connexion with Heloise. It was not till the 19th century, when Cousin in 1836 issued the collection entitled Ouvrages inedits d'Abelard, that his philosophical performance could be judged at first hand; of his strictly philosophical works only one, the ethical treatise Scito te ipsum, having been published earlier, namely, in 1721. Cousin's collection, besides giving extracts from the theological work Sic et Non ("Yes and No") (an assemblage of opposite opinions on doctrinal points, culled from the Fathers as a basis for discussion, the main interest in which lies in the fact that there is no attempt to reconcile the different opinions), includes the Dialectica, commentaries on logical works of Aristotle, Porphyry and Boethius, and a fragment, De Generibus et Speciebus. The last-named work, and also the psychological treatise De Intellectibus, published apart by Cousin (in Fragmens Philosophiques, vol. ii.), are now considered upon internal evidence not to be by Abelard himself, but only to have sprung out of his school. A genuine work, the Glossulae super Porphyrium, from which Charles de Rémusat, in his classical monograph Abelard (1845), has given extracts, remains in manuscript.
The general importance of Abelard lies in his having fixed more decisively than anyone before him the scholastic manner of philosophizing, with its object of giving a formally rational expression to the received ecclesiastical doctrine. However his own particular interpretations may have been condemned, they were conceived in essentially the same spirit as the general scheme of thought afterwards elaborated in the 13th century with approval from the heads of the church. Through him was prepared in the Middle Age the ascendancy of the philosophical authority of Aristotle, which became firmly established in the half-century after his death, when first the completed Organon, and gradually ail the other works of the Greek thinker, came to be known in the schools: before his time it was rather upon the authority of Plato that the prevailing Realism sought to lean. As regards his so-called Conceptualism and his attitude to the question of Universals, see Scholasticism. Outside of his dialectic, it was in ethics that Abelard showed greatest activity of philosophical thought; laying very particular stress upon the subjective intention as determining, if not the moral character, at least the moral value, of human action. His thought in this direction, wherein he anticipated something of modern speculation, is the more remarkable because his scholastic successors accomplished least in the field of morals, hardly venturing to bring the principles and rules of conduct under pure philosophical discussion, even after the great ethical inquiries of Aristotle became fully known to them.