Siger de Brabant

Siger de Brabant (also Sigerus, Sighier, Sigieri, or Sygerius), (c. 1240 – 1280s), a thirteenth-century philosopher from the southern Low Countries, was one of the inventors and major proponents of Averroism. During the thirteenth century in Paris, Siger was recognized as a leader of those who interpreted Aristotle through the perspective of Averroes. He was considered a radical by the conservative members of the Roman Catholic Church, but it is suggested that he played as important a role as his contemporary Thomas Aquinas in the shaping of Western attitudes towards faith and reason.

Siger's political theory held that good laws were better than good rulers, and criticized papal infallibility in temporal affairs. Siger’s importance to philosophy lies in his acceptance of Averroism in its entirety, which brought upon him the opposition of Albertus Magnus and Aquinas. He promoted Averroist ideas, such as the eternity of matter; the principle that God operated on the universe through the intermediary of a progressive series of emanating intelligences; and the concept of a single universal intellect. In December of 1270, Averroism was condemned by ecclesiastical authority. During his entire career, Siger de Brabant was exposed to persecution both from the Church and from purely philosophic opponents.


In the Divina Commedia:Paradiso, X, 136 Dante places Siger in the wise men’s circle in Paradise, at the side of Aquinas and Isidore of Seville; he puts his praises on the lips of Thomas Aquinas, which puzzles commentators, since the Averroists were amongst Thomas Aquinas’ adversaries. Dante probably knew of Siger from the chronicler only as a persecuted philosopher.


Few concrete details are available about the life of Siger de Brabant. He was born around the year 1235, was awarded a Master of Arts at the University of Paris, and became a teacher in the faculty of arts there. In 1260, Siger and his colleagues initiated a series of rational lectures on the newly translated theories of Aristotle, with almost complete disregard for the teachings of the Roman Catholic Church. Siger’s philosophical sources were Aristotle, Proclus, Avicenna, Averroes and Thomas Aquinas. In 1266, while he was attached to the Faculty of Arts at the University of Paris, a conflict arose among the four "nations" (students in the Faculty of Arts were grouped into four nations according to their regional origin and language). The papal legate decided that Siger was the ringleader, and threatened him with death. Bonaventure and Aquinas both took offensive actions against the teaching of Siger, and in 1270 he was condemned for his Averroistic theories by the bishop of Paris, Etienne Tempier, who pointed out thirteen errors in the teachings of Siger and his supporters. He defended himself by saying that he was simply explaining the theory of Aristotle and did not intend to affirm anything that was inconsistent with the Catholic faith. To some extent, he also altered his position. It has been implied that he was turned from Averroism by the writings of Thomas Aquinas, but there is no evidence that he abandoned the theories of Averroes.

During the succeeding ten years he wrote the works which are ascribed to him and were published under his name by P Mandonnet in 1899. The titles of these treatises are:

  • De anima intellectiva (1270)
  • Quaestiones logicales
  • Quaestiones naturales
  • De aeternitate mundi
  • Quaestio utrum haec sit vera
  • Homo est animal nullo homine existente
  • Impossibilia

In 1271 he again became embroiled in a party struggle. The minority among the nations chose him as rector in opposition to the elected candidate, Aubri de Rheims. For three years the strife continued, and was probably based on the conflict between Siger and Pierre Dubois, who were Averroists, and the more orthodox schoolmen. The matter was settled by the Papal Legate, Simon de Brion (who later became Pope Martin IV). Siger retired from Paris to Liège.

Averroism was controversial because it presented the thought of Aristotle in its original form, with no attempt at reconciliation with Christian beliefs. Siger was accused of teaching "double truth," the concept that faith and reason revealed different truths; something could be true according to reason, and the exact opposite could be true according to faith. It is more likely that Siger, as a scholastic, did not teach double truth, but tried to synthesize faith and reason.

In 1277 there was an official condemnation of Aristotelianism which included a special clause directed against Boetius of Dacia and Siger of Brabant. Again Siger and Bernier de Nivelles were summoned to appear on a charge of heresy, especially in connection with the Impossibilia, which discussed the existence of God. It appears, however, that Siger and Boetius fled to Italy where, according to John Peckham, archbishop of Canterbury, they died in miserable circumstances.

It is unclear what caused Siger‘s death, which occurred at Orvieto. A Brabantine chronicle relates that he was stabbed by an insane secretary (a clerico suo quasi dementi) who used a pen as the murder weapon. Siger’s critics claimed that since he had done so much damage with his pen, it was a fitting end. Dante, in the The Divine Comedy|Paradiso (x. 134-6), says that Siger found "death slow in coming," and some scholars have concluded that this indicates death by suicide. A thirteenth-century sonnet by one Durante (xcii. 9-14) says that he was executed at Orvieto: "a ghiado it fe' morire a gran dolore, Nella corte di Roma ad Orbivieto." This may have taken place between 1283-1284, when Martin IV was in residence at Orvieto. Siger’s fellow radicals were hiding in response to the Condemnations of 1277 and there was no investigation into his murder.

Latin Averroism: Siger de Brabant

Ibn Rushd or Averroes (1126-1198) was born into a Mohammedam family at Cordoba, in Spain. He studied law and the sciences, lived for a time in Marrakesh, and served as a judge in Seville. His major works were commentaries on the writings of Aristotle, whom he regarded as the greatest genius of all time and praised as “the production of nature for the purpose of showing supreme human perfection.” Like other Arabic thinkers, his philosophy included elements of Neoplatonism. He regarded God as the Prime Mover, in accord with Aristotle’s teachings. However, God was separated from the world and did not exercise any providential influence on it. Between God and human beings there was a continuity of intelligences. His other significant theories concerned the eternity of matter and monopsychism, the sharing of one intellect by all human beings. Averroes rejected the concept of individual immortality.

At the beginning of thirteenth century, the theories of Aristotle were imported to the West through the detailed commentaries of two Islamic philosophers, Ibn Sina (or Avicenna (980-1037)), and Ibn Rushd (or Averroes). The ideas introduced by these commentaries had a profound influence on Western culture, especially on the traditional doctrines of Christianity. Albertus Magnus (1193? -1280), a Dominican friar, and Thomas Aquinas criticized Averroes’ view of intellect. Bonaventure, of the Franciscan Order, spoke in a sermon of “some students of philosophy who say certain things which are not true according to faith; and when they are told that something is contrary to faith, they reply that Aristotle says it, but that they themselves do not assert it and are only reporting Aristotle’s words.” In 1270 Stephen Tempier, the bishop of Paris, condemned Averroism.

Siger de Brabant was a major proponent of Averroism. Though Siger regarded his theory as true Aristotelianism, Averroism actually differed from the theory of Aristotle on several significant points. Aristotle perceived God as the ultimate final cause; Siger followed Averroes’ concept of God as the first creative, or active, cause. He adopted Avicenna’s explanation that God operates on the world through an intermediate succession of emanating intelligences. Initially Siger followed the Arab philosophers’ ideas on monopsychism and the eternity of the universe. While Aristotle had taught that there had been no “first beginning” and so the universe had existed eternally, the Arab philosophers proposed that events occur in eternal recurring cycles, and so the universe has no end.

It appears that Siger later retracted his ideas on monopsychism and the eternity of the universe; in later comments on De anima intellectiva he admits that monopsychism is not true and accedes to the objections of Thomas Aquinas, who issued a strong refutation in ”De unitate intellectus, contra Averroistas(On the Unity of the Intellect against the Averroists). In Questions on the Physics he states that motion is not, after all, eternal and that it must have had a concrete beginning, which cannot be rationally demonstrated. It is possible that he has made these retractions in order to mollify the Roman Catholic authorities after the condemnation of Averroism in 1270.

See also


  • Copleston, Frederick, S.J. A History of Philosophy, Volume II, Medieval Philosophy from Augustine to Duns Scotus. New York: Doubleday Image Books, 1993.
  • Hissette, R. Enquête sur les 219 articles condamnésà Paris le 7 mars, 1277. Louvain: Publications Universitaires; Paris: Vander-Oyez, 1977.
  • Mandonnet, P. Siger de Brabant et l’ averroïsme latin au XIIIe siècle, Les Philosophes Belges VI-VII. Louvain: Institut supérieur de philosophie, 1908-1911.
  • Van Steenberghen, F. Maître Siger de Brabant. Louvain: Publications universitaires, Paris: Vander-Oyez, 1977.
  • This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.

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