The intellectual florescence of thirteenth-century France, and Paris in particular, was vibrant, yet it confronted scholastic thinkers with a range of both new and continuing problems. The most famous of the continuing problems was the how to fully reconcile Aristotelian philosophy with revealed scripture. Both had lengthy commentary traditions that complicated the attempt. Christian doctrine had the four Church Fathers as well as key medieval works, such as Peter Lombard’s Sentences, while Aristotle had commentaries from both the late antique and Islamic worlds as well as Christian commentaries for those few works available in Latin in the early Middle Ages. The most famous of the Muslim Aristotelian scholars in Europe was Ibn Rushd, known in Latin as Averroës, or often simply The Commentator. A twelfth-century Andalusi Islamic jurist, physician, theologian, and philosopher, Averroës presented curious and thoughtful scholars, such as Albertus Magnus, with the difficult question of how to use and learn from the knowledge that Averroës provided while not stumbling over his religiously problematic positions.

At the heart of this conflict was the changing notion of auctoritas (authority). As late as the early twelfth century, men like William of St. Thierry were writing that knowledge was acquired through the intellect while auctoritas was exclusively the means for acquiring faith.[1] However, this long-held view changed at the turn of the twelfth century, which saw the end to what is sometimes called the Age of Authority, because men noted that authority was the weakest form of proof, as Thomas Aquinas observes time and again in his famous Summa theologiae.[2] The reception of Aristotle in thirteenth-century Europe had created a new, more logical form of theology, one that addressed the entire cosmos, entwining theology and science in new ways.[3]

European thinkers had few qualms with absorbing practical knowledge like medicine from Arabic sources. This was in large part because it did not contradict orthodoxy, but also because scholars were translating or building upon such Greek and Latin authorities as Galen and Hippocrates, who had been accepted for centuries. For instance, the eleventh-century arrival of Constantine the African (1017-1087) in Italy was followed by his Pantegni, an abbreviated translation of the Kitāb al-malikī (The Royal Book) by ʿAlī ibn al-ʿAbbās al-Majusi, known as Haly Abbas in Latin. Constantine also translated the compendium composed by al-Majusi of the medical works of Hunayn ibn Ishaq al-'Ibadi (ca. 809-873), whose own work was based on Galen’s Art of Medicine. This compendium became known as the Isagoge of Johannitius and quickly became the standard Galenic text used in Europe, even after much better translations became available.[4] In twelfth-century Spain, Gerard of Cremona, a prolific and skillful translator, translated Ibn Sina’s (or in Latin Avicenna’s) Canon of Medicine, a text that quickly became an enduringly popular medical textbook in Europe.[5]

Averroës soon joined their ranks as one of the preeminent authorities on medicine, a position solidified by the translation of his al-Kulliyyat, known as the Colliget in Latin. The Colliget is a compendium of medical knowledge, or “generalities,” written in the 1150s and 60s. Drawing deeply upon Galen and moderately upon Hippocrates, it is divided into seven books on the anatomy of the organs, health, sickness, symptoms, drugs and foods, hygiene and therapy. It was intended to complement Ibn Zuhr's al-Taisir to form a complete medical text, the success of which is testified to by its frequent discovery in printed Latin editions that join the two together.[6] However, many scholars, including Nancy Siraisi, note that Averroës’ medical works were not translated in documented instances until, 1285, far too late for Albertus to use them.[7] Nevertheless, Albertus was clearly aware of Averroës as a medical authority, whether through word of mouth or earlier translations now lost to us.

This awareness is made clear in De animalibus (On Animals), Albertus Magnus’ lengthy commentary on the three Aristotelian works on animals that were compiled in Arabic as the Kitāb al-Hayawān in the ninth century, namely, Historia animalium (History of Animals), De partibus animalium (On the Parts of Animals), and De generatione animalium (On the Generation of Animals).[8] In an introductory note before a discussion Albertus says

Since it is our intention to pass on perfect doctrine in these matters, we will first set out the opinion of Aristotle on this matter, with a clear explanation. Second, we will point out what Galen says to the contrary, and third, we will introduce the solution of Avicenna in these matters. Fourth, however, we will point out all that Averroes says that is contrary to Avicenna and we will set forth his solution. Fifth, and finally, we will educe our opinion from all these, and we will prove it by use of reason and sold experiential knowledge that is completely trustworthy.[9]

This places Averroës firmly in a top-tier list of medical authorities: Aristotle, then Galen, followed by Avicenna, and finally Averroës. This not only places Averroës in exalted company, but also implies that Albertus knew of his medical opinions before they were demonstrably available in Latin codices. This authority is clearly borne out by the fact that Averroës’ opinions are important enough to be reconciled with those of Galen. Albertus writes

Avenroys does not entirely agree with this assessment [of Galen’s] in a certain book he wrote on the dispositions of the heart. His statements are as follows. He says that the origin of the food-power (that is nutrimental power) is in the heart, as is the origin of the spirit, veins, and nerves, so that the active heat [calor agens] and receptive blood [sanguis patiens] might be in one and the same place.[10]

Nor is this the only example in De animalibus of Averroës as a medical authority. In fact, Albertus devotes several chapters to his discussion of the various opinions on the veins and circulatory components, with Averroës’ name again appearing alongside Avicenna’s, this time as an example of those who have pointed out the errors Galen made when he does not allow for the heart being the home of “the principle of sensation and movement” by “distinguishing and determining sensations.”[11] Albertus couples the two physicians yet again in a later discussion on whether or not female sperm has the same formative power as the male. In support of his view that it does not, Albertus writes

Averroes and Avicenna follow this view, as do all those who have studied natural matters well and carefully. Some physicians, however, are ignorant of reason and philosophy. They offer the opinion of Galen even though it is not their business to offer an opinion of one or the other.[12]

Clearly then, he saw the Andalusi as physician and a genuine medical authority, and one worthy of comparison with the most important names in pre-modern medical theories, particularly because he offered Albertus an attempt at reconciling discordant authorities, namely Aristotle and Galen.

However, it was not just medical works that were translated in the central Middle Ages. The twelfth century witnessed a translation movement that occurred at the meeting points between Christendom and the Islamic World, in places like Iberia and Sicily, and the product spanned nearly the entirety of contemporary science. Indeed, the large majority of the works fell under science in the Aristotelian or medieval sense, including works of anatomy and medicine, animals, astronomy, astrology, creation and generation, motion, physics, and human psychology and the soul.

Albertus Magnus was interested in all of them, especially the works of Aristotle, and was determined to comment upon the entire Aristotelian corpus. In doing so he came into consistent contact with Averroës’ commentaries on the same works. These commentaries established Averroës’ usefulness as an authority, yet they also strained Christian European scholars’ ability to accept all of his work because of his heretical views on the soul. Aristotle’s divides the intellect into possible, passive, and active, but is unclear on whether this intellect is one or different in each human being. Because of his contact with the Almohad theology that emphasizes unity and because he strove to be true to Aristotle’s original intent, Averroës answers emphatically that there is only one possible intellect and only one agent intellect.[13] This is problematic because it leaves humans with only a corporeal individuated passive intellect, one that has no individual immortality. The passive intellect, also known as the possible intellect, is seated in the animal spirits of the brain. Even though these spirits, distilled from the blood by the carotid arteries, are incredibly thin and air-like or flame-like, they are still material. This location of the passive intellect, therefore, means that this part of the soul is necessary to the body while also being dependent on it. In other words, the animal parts of us are individuated for Ibn Rushd, but the rational soul, the part that makes us human instead of animal, is the same in all people with no differences that can continue after death. One man’s rational soul, then, is not really his, but part of the same unified agent intellect to which it will return after the body’s death.

This is theologically alarming in the extreme for Christian thought, certainly for the theologians at the University of Paris, and for Albertus in particular. No individual afterlife for the soul is fundamentally unsupportable. One would expect Albertus to vigorously defend the notion of individual afterlife in this conflict of ideas, and indeed he does. However, Albertus’ use of Averroës in his religious works, such as his Summa theologiae, are not as vitriolic as one would expect. Indeed, Averroës remains an important authority to either be relied upon or at least contradicted with reason for the majority of this text.

Albertus’ Summa theologiae does contain the expected condemnation of Averroës’ theory of the unity of the intellect. For instance, when he address the question of “whether a single intellect is in all bodies or many” he responds “certain Arabs, namely Averroës, said that the intellect is one in all souls and in all human beings. And this error grew so powerful that many have defended it.”[14] Albertus does not hesitate to condemn this defense, arguing that “this dangerous error is beyond measure,” that he had investigated it, and that “because the defenders of this heresy say that [this error] is in accordance with philosophy, it is right that the Catholic faith put something else in its place in accordance with theology.”[15] Albertus continues on, saying that in order to tear down this error, it is necessary to show what kind of error it is.

In his offered solutio to this question, Albertus uses Averroës’ authority to counter his own position, noting that Averroës says, and adding that it is true, that the intellects of the soul are incorruptible and therefore lead to an individual immortal soul that cannot be absorbed by a unified intellect or soul after death. In using Averroës’ own words to dispute one of his own theories, Albertus is using an almost Socratic method of rhetoric. This is not the angry, vitriolic language of the earlier section, but a more gentle, reasoned questioning and condemnation of Averroës’ metaphysics. In a third example Albertus chides Averroës for not disagreeing with Aristotle on a problematic stance on the intellectual soul, but the discussion of the error focuses on Aristotle.[16] These second and third disagreements are thus gentler in nature than the first emphasis on the intense danger posed by Averroës’ erroneous stance on the unity of the intellect.

In all, Albertus cites Averroës by name 23 times in his Summa theologiae, and only three of them are in the context of directly condemning his theory of the unified intellect. The other twenty times that Averroës’ name is brought up he is appealed to as a true authority. In the first few pages of Albertus’ Summa Averroës is quoted between two Psalms and Dionysius’ On the Divine Names, noting among other things his position that all men desire knowledge and that this knowledge is comprehended by the strength of the divine intellect that is God’s light, or lumen in Latin, that moves the intellect to comprehend actively.[17] In another early portion of the text, Averroës is again mentioned by name to defend the idea that all men seek knowledge, but this time he name is paired with Aristotle.[18]

Averroës is also used as an authority on astronomy in discussions on the celestial spheres. Albertus credits him with the idea that the substance of celestial bodies is superior to that of human ones.[19] He is cited again by Albertus together with Masha’allah ibn Atharī, an eigth-century Basran Persian Jewish astrologer and astronomer, on the substance and motion of the sphere.[20] Averroës is also cited on other issues of movement. The topic of the movement of the soul sees him cited together with Avicenna as a follower of Aristotle, while he is cited alone on the idea that in an uneven relationship, the worthier thing cannot be moved by something less worthy.[21]

It is not just Averroës’ name alone that is given authority. There are also numerous specific mentions of Averroës’ commentaries on Aristotle. For instance, Albertus cites the commentaries on Book II of De anima (On the Soul) on the idea of God’s will changing potential motion into actual motion, a citation he repeats a second time in a different section of the same part.[22] Albertus continues citing Averroës’ commentary of Book III of De anima when he notes that Averroës says that the intellect is the locus of intelligible species.[23]

Albertus also cites Avicenna’s commentary on Aristotle’s Physics, including two sections on motion and change from Book III, one of which differentiates between the motion of place and the motion of change.[24] Motion continues to be a theme for which Albertus leans heavily on the authority of Averroës’ commentary, writing that

Therefore generation and corruption, as Averroës says in his commentary on Book III of the Physics, are without a middle, and are not in time, but in the present: because they are the limit of motion, and [are] not motion.[25]

There is also a mention of Book II of the commentary in which Aristotle and Averroës’ opinions on the contents of the soul are linked. Another in Book IV follows a reference to Augustine’s City of God before noting that Aristotle and Averroës agree with it, along with Avicenna in his work Sufficiency.[26] Book IV’s commentary is also cited for it concordance of Aristotle and Averroës, noting the relationship between time and the soul.[27]

This consistent use of Averroës as an authority continues at varying levels in the majority of Albertus’ works, including his commentaries on Ethics, Politics, On Generation and Corruption, On Minerals, On Memory and Reminiscence, On Sense and Sensation as well as more overtly religious works such as his commentary on Peter Lombard’s Sentences, which contains nine citations to Averroës. Those in which he is not cited are a mixture of Albertus’ works on books of the Bible and works of Aristotelian commentary such as Analytica priora. In short, Averroës’ theological errors clearly did not prevent Albertus from engaging with his authoritative ideas and commentaries.

However, this willingness to engage with Averroës as an authority and as the source of theological error, to hold the same figure as both authority and heretic, was not the norm, and even less accepted by the end of the thirteenth century. The Dominicans in Paris are credited with many attempts to reconcile the classical philosophy with church auctoritas, including one of the first attempts in the early thirteenth century to return to a “pure” Aristotle in hopes of removing what was seen as pagan or polytheistic.[28] Later in the century, Albertus’ pupil, Thomas Aquinas, did his best to juggle the authorities of reason and revelation, while writing a critique of all levels of Averroës’ unity of the intellects. This De unitate intellectus contra Averroistas (On the Unity of the Intellect Against the Averroists) and his other writings made clear that the soul was individuated enough for individual immortality because of individual possible and agent intellects in each human being.

However, these valiant attempts at reconciliation, including efforts to provide a framework for when Averroës should be used as an authority and when he should be refuted but acknowledged, could not prevent an ultimate confrontation between scholars and church authorities, who had long been suspicious of Aristotle and any other authority of pagan or non-Christian origin. The well-known Condemnation of 1277 makes this clear. In the condemnation Etienne Tempier, Bishop of Paris, condemned the theology students of Paris for discussing “certain obvious and loathsome errors.”[29] They are further condemned because “they say that these things are true according to philosophy but not according to the Catholic faith.”[30] Seeing these statements as proliferating error, this condemnation accused the students of having two separate and contradictory conclusions, one based on the knowledge of reason and the other on revelation, something that could not be allowed. Unsurprisingly, the only authorities cited by Etienne were Gregory the Great and the Bible: a Psalm, Corinthians, Isaiah, and Ecclesiastes.[31]

A large number of the 219 condemned propositions deal with positions attributed to Averroës’ theory of the unity of the intellect and those who defended his errors in Latin. The majority of these occur in a group of around fifteen statements, beginning with 115, which states “That God could not make several numerically different souls.”[32] This plays on both Etienne’s overall theme of condemning anything that limits God’s power while also clearly attacking Averroës most problematic assertion.

This condemnation, just after Thomas Aquinas’ death and only three years before that of Albertus Magnus, marked the high point of the conflict over authority in Paris, building upon largely ignored prohibitions of Aristotelian works in 1210, 1215, and 1231. However the opposition was not able to remove the condemned ideas from the University of Paris, much less other European universities. Because many of the condemnations were based on the work of Thomas Aquinas, they were officially lifted in the early fourteenth century with his canonization. Because of both his commentaries and his medical works Averroës would remain integrally intertwined with European learning in his role as an authority, whether to be praised or proven wrong. Indeed, until at least the nineteenth century, his authority would be greater in Christian Europe than in the Islamic world.


    1. Heinrich Fichtenau, Heretics and Scholars in the High Middle Ages: 1000-1200, trans. Denise A. Kaiser (University Park, PA: Pennsylvania State University Press, 1998), 216-217.return to text

    2. Thomas Aquinas, Summa Theologiae, Part I, Question I, Article 8.return to text

    3. Ibid., 314-315.return to text

    4. Faith Wallis, Medieval Medicine (University of Toronto Press, 2010), 139.return to text

    5. Edward Grant, A Sourcebook in Medieval Science (Cambridge: Harvard University Press, 1974), 37.return to text

    6. Ahuva Gaziel, “Questions of Methodology in Aristotles’s Zoology: A Medieval Perspective,” Journal of the History of Biology 45 (2012): 332.return to text

    7. Nancy Siraisi, “The Medical Learning of Albertus,” in Albertus Magnus and the Sciences: Commemorative Essays 1980, ed. James A. Weispheipl, (Toronto: Pontifical Institute of Medieval Studies, 1980), 396.return to text

    8. Gaziel, 331.return to text

    9. De animalibus 3, 1, II. English translation from in Albert the Great, On Animals: A Medieval Summa Zoologica, trans. Kenneth F. Kitchell Jr. and Irven Michael Resnick (Baltimore: John Hopkins Press, 1999), 351.return to text

    10. De animalibus, 3, 1, V. Kitchell, 365.return to text

    11. De animalibus, 3, 1, VI. Kitchell, 375.return to text

    12. De animalibus, 3, 2, VIII. Kitchell, 420.return to text

    13. Averroes, Long Commentary on the De Anima of Aristotle, trans. Richard C. Taylor (New Haven: Yale University Press, 2009). See page 386 specifically, though the entire work is useful. See also Herbert Davidson, Alfarabi, Avicenna, and Averroes On Intellect: Their Cosmologies, Theories of the Active Intellect, and Theories of Human Intellect (Oxford University Press, 1992).return to text

    14. Albertus Magnus, Summa theolgiae, Pars II, tract.13, q.77, p. 75a. Translated from the Latin in Auguste Borgnet’s edition, 1894-95.return to text

    15. Ibid. Pars II, tract.13, q.77, p. 75a.return to text

    16. Ibid., Pars II, tract.13, q.77, m.3, p.93b.return to text

    17. Ibid, Pars I, prol., p.3.return to text

    18. Ibid, Pars I, tract.3, q.13, m.1, p.54b.return to text

    19. Ibid.,Pars II, tract.11, q.63, m.2, p.609b.return to text

    20. Ibid., Pars I, tract.18, q.75, m.2, p.786a.return to text

    21. Ibid., Pars II, tract.11, q.53, m.3, p.567a and Pars II, tract.11, q.53, m.3, p.569b.return to text

    22. Ibid., Pars I, tract.4, q.21, m.1, p.150a and Pars I, tract.8, q.36, m.3, p.382b.return to text

    23. Ibid., Pars II, tract.13, q.77, m.3, p.81b.return to text

    24. Ibid., Pars I, tract.13, q.53, m.2, p.545b and Pars I, tract.18, q.74, m.2, art.1, p.770a.return to text

    25. Ibid., Pars I, tract.18, q.74, m.2, art.2, p.775b.return to text

    26. Ibid., Pars I, tract.5, q.22, m.1, p.159a and Pars I, tract.5, q.22, m.2, art.1, p.161b.return to text

    27. Ibid.,Pars I, tract.18, q.74, m.1, p.766b.return to text

    28. See Fichtenau.return to text

    29. Condemnation of 1277 in Philosophy in the Middle Ages, 2nd ed., Arthur Hyman and James J. Walsh, eds. (Indianapolis: Hacket Publishing, 1973), 584.return to text

    30. Ibid. return to text

    31. Ibid., 584-585.return to text

    32. Ibid., 589.return to text