John of Jandun was of course one of the authors to be treated in my repertory of Parisian masters of arts, and so I discovered that John not only wrote philosophical commentaries and treatises, but also a laudatory poem on Paris. This, I could sympathise with, as Paris had from an early age on attracted and fascinated me. More I read on this rather well-known scholar, who never reached the fame of a John Buridan or Thomas Aquinas, the more I felt that it would be interesting to dive into his life and intellectual production. Thus, I finally made time – after finishing all kind of more serious research, published in print or on my personal website – for the leisurely activity of reading and thinking on John of Jandun. What follows is a partial account of this slow process.


A sketch of his life


I had a pleasant surprise when looking up the article on John of Jandun in the Dictionnaire des lettres françaises, for this has been written by my colleague and friend Zénon Kaluza[1], a fine connoisseur of fourteenth-century philosophy. So, I could more or less translate his findings, completing and correcting them with the earlier – and of course much longer – publications of MacClintock and Schmugge[2], as well as with more recent literature[3].

John of Jandun[4] was born around 1285 in the small village of Jandun in the diocese of Reims and, after primary and secondary education in the region (but this is not documented), went to Paris in order to start his studies at the faculty of arts. We do not know who were his masters, but it is sure he himself became a master of arts before 1310 (he probably obtained his licence around 1307) and taught in Paris from that time onwards[5]. He must have held his school in the rue de Fouarre, the place where arts masters taught the programme of the faculty of arts.

During this period, he probably met Pietro d’Abano, who lectured in Paris around 1310 and on one of whose works, the Expositio problematum, he later wrote a commentary[6]. Early in his career as master of arts, John engaged in the discussion on the sensus agens; his Sophisma de sensu agente is dated from 1310 and in his Questiones de anima he refers to it as “in primo tractatu de sensu agente, quem ordinavi”[7]. Around 1311 or 1312 he met Marsilius of Padua, who had come to Paris and was rector of the university – and thus master of the arts faculty – in December 1312[8]. Whether John contributed to Marsilius’s treatise Defensor pacis or not, both John and Marsilius taught in Paris philosophical concepts commonly conceived of as ‘averroist’, as presented for instance by Pietro d’Abano and Thomas Wylton.

At about this time, John already considered himself as the first of the arts masters in Paris, as we can gather from an interesting note in a manuscript containing the Expositio problematum by Pierre d’Abano edited by John of Jandun: “Et ego Joannes de Genduno qui Deo gratias credo esse primus inter Parisiis regentes in philosophia ad quem predicta expositio pervenit per dilectissimum meum magistrum Marcilium de Padua”[9]. So, it is possible that Marsilius had brought the Expositio with him from Italy and he may have given it to John early on in their relationship, in 1313 or 1314.



In 1315 he is listed as one of the original members of the Collège de Navarre and is designated in its statutes as magister artistarum[10]; a document reproduced by MacClintock lists fifteen students[11]. He must have been indeed a well-known and respected master and he had already composed a number of works, among which the questions on the sensus agens (a later text, not to be confused with the sophisma quoted above), as we will see below[12].

In 1316 he was given, sub exspectatione, a canonry of Senlis by Pope John XXII[13], which would give him a regular income – if he effectively received it – even when not living in Senlis(usually the main portion was received if one was teaching or holding an office that required residency although the full amount, including the other part was based on attendance in choir[14]). Anyway, some of his important commentaries, for instance the one on the De anima, have been composed afterwards, clearly in Paris. Also, the fact that the pope granted him an expectation would mean that he probably was by that time an advanced student in theology[15].

He was active as teacher of arts for more than ten years, as shown by a number of writings dating from 1307, 1309, 1310, 1315, 1317, 1318, 1319, 1320 and 1321. In 1323 he completed his De laudibus Parisius, a poem on the many attractions of the city that he manifestly loved, although the often satirical style reveals the distance he felt at this time towards his university[16]. The next year, in June 1324, he is mentioned in a business transaction: a house belonging to the Sorbonne, in the Rue Cloître-Saint-Benoît, was rented out for life to a certain Nicholas of Vienne, who had been rector of the university in 1313, and to John of Jandun “consequenter si supervixerit eidem magistro Nicolao, similiter ad vitam ipsius magistri Johannis”[17]. This seems to indicate that at this moment he had not yet decided to leave Paris with his friend Marsilius[18].

During his career as a teacher of arts, John was of course in contact with his fellow masters of arts, but also with other masters and students in different disciplines. As recent research on commentaries on the Sentences by William Duba[19] and Chris Schabel has shown, John was part of a circle of mainly young Italian theologians enjoying the patronage of Cardinal Iacopo Caetani Stefanesci, in the early fourteenth century, among whom the secular master of theology Thomas Wylton, who taught at the College of the Sorbonne since 1312, and his student (the cardinal’s nephew) Annibaldo de Ceccano. Another bachelor of theology, Landolfo Caracciolo, gave a short final lecture around June 28, 1319, at the end of his lectures on the Sentences. In this document, edited and analysed by William Duba, Landolfo gives a picture of patronage and partisanship as well as of the relations between masters and bachelors[20], an interesting focus on part of the Parisian intellectual landscape during this period. That John of Jandun, “Prince of the Averroists”, was part of this circle is shown by several facts: he dedicated his final commentary on book III of the De anima to Cardinal Stefanesci and a version of his commentary on the Rhetoric to Annibaldo[21]. Moreover, he came to the defence of Annibaldo de Ceccano, bachelor in Thomas Wylton’s school, attacked by Landolfo in his final lecture mentioned before. A question by Landolfo (“Utrum contradictoria simul sunt vera”) is followed in ms. Erfurt, Amplon. 2° 178 by a refutation by John of Jandun[22].

We can also point to John’s connections with prominent personalities among the nobility and the Church officials to whom he dedicated some of his works: the Questio de pluralitate formarum, finished in 1317, to Louis of Melun, the commentary on the Rhetoric to Annibaldo de Ceccano, the commentary on the third book of De anima to Etienne Stefanesci, nephew of the Cardinal mentioned above and probably one of John’s students[23].

For his relations with fellow teachers and farther aways colleagues, we can mention first Bartholomew of Bruges, with whom he entertained very early in his career a controversy on the problem of the sensus agens[24], and also on the question of the intelligible species[25].

Among the other masters present in his debates is Thomas Wylton, mentioned above as the leader of a circle of young theologians[26]. Apart from Jandun’s treatise De infinitate vigoris Dei (dating from 1317), in which he repeats the arguments cited by Wylton in a quodlibetical question in support of the view that an intensive infinity of divine power could be demonstrated if movement were assumed to be eternal[27], we can also point to John’s commentary on the De anima (see Chapter 4). Here, he repeats extensive passages from Wylton’s Questio de anima intellectiva[28]. Kaluza, in his article quoted above, says that John has ‘plundered’ his colleagues, namely Thomas Wylton, an appreciation that has of course to be qualified in the light of more recent evaluations of medieval ‘plagiarism’. Anyway, it is clear that John considered Wylton as an authority in these matters.

As mentioned above, the Franciscan Landolfo Caraccioli composed a question on the problem of contradictory terms being simultaneously true, immediately followed in the manuscript (Erfurt, Amplon. F. 178) by a question of Jandun, in which he refutes in detail Landolfo’s question (“Utrum contradictoria sint simul vera”)[29]. He begins by saying that ‘a certain theologian’ determined this question and he is very critical, as we can see, for instance, in a passage where he qualifies the acceptance of simultaneous truth of contradictories as ridiculous and compares this with styles of dress:


Sed quia derisibile non habet naturam fixam, immo id quod aliquando fuit derisibile et ridiculum postea in reverendum aut saltem non deridetur a multis, ut videmus de vestibus quorumdam dominarum et nobilium huius temporis que vocantur gallice a la nova manire, id est ad novam maneriem, idcirco non est impossibile quod duo contradictoria esse simul vera prohibeatur derideri si a viris solemnibus hoc teneatur et irrevocabiliter defendatur[30].


Here, we have at the same time a nice example of harsh criticism and of John’s use a French tournures, which is a recurrent feature of his style. We can also note that John, the respected intellectual, was not blind to the secular world that surrounded him

In another independent question, the De pluralitate formarum, John also debates with a theologian, this time anonymous, as we will see below in the chapter concerning his commentary on the Physics (Chapter 2). In these times, Mendicants were teaching in Paris as elsewhere, and their works were of course known and discussed by the seculars masters[31].

We also encounter other colleagues, masters in the arts faculties, in the various commentaries of Jandun, for instance his contemporary Matthew of Gubbio, master of arts at Bologna in the early decades of the fourteenth century. This Italian scholar debated about the question of the nature of the concept species in one of his disputed questions[32], a theme which is also debated in one of Jandun’s questions in his commentary on the Metaphysica, as we will see below (Chapter 10). As Saccenti[33] remarks, John’s commentary was certainly known to the Bolognese masters, as the narrow relation between John of Jandun and the masters in Bologna suggests. So, here, the discussion of an important matter by John can be found in a disputed question of Matthew.

As Brenet noted, even though we do not find many names in John’s commentaries and questions, it is clear that he is grappling with more or less influential colleagues, like Bartholomew of Bruges, Radulphus Brito or Durand de Saint-Pourçain[34]. Kaluza, in his presentation mentioned above, also mentions his polemics with contemporary philosophers, namely Bartholomew of Bruges and Radulphus Brito again, but also Maino dei Maineri[35].

John seems to have had low esteem for the (Parisian) theologians, as indicated by MacClintock[36],  who quotes a passage of the Questiones De anima, remarking on the failure of certain theologians to understand the statement that the soul is unique for all men, eternal and separate, and explaining this by a lack of attention to natural philosophy:


thus they have passed over many of the conclusions of natural philosophy without a sufficient examination of them. For I think that most of those who spend their days in the study of philosophy could understand this position; but when their duties prevent them, they have not written about it expressly[37].


The confidence of Jandun in his own philosophical insight compared to that of the Parisian theologians is also evident in the harsh and ironic criticism of a doctrine of “frater Thomas” (Aquinas). In the third book of his Questiones de anima, he argues against Aquinas’ conception of the soul as a form that gives being to the body in a purely philosophical way[38].

We have to note that in John’s time, and already since the mid-thirteenth century, the Faculty of Arts was perceived to be a faculty of philosophy, even if a part of philosophy was pursued at the Faculty of theology[39]. John, who was considered by his contemporaries as “unus de melioribus philosophis, qui multum intendit studio philosophie”[40], can be quoted as one of the eminent examples of the kind of arts masters who did not doubt the importance of their place in the academic world.

As we saw above, John was known as the “Prince of the Averroists”[41] and we can measure the importance of his Averroistic theories for instance by the reaction of Raymond Lulle. As Nathalie Gorochov shows, this philosopher of a very different kind, when he visited Paris in 1310, already asked king Philippe le Bel to “extirpate” the works of Averroes from the city of Paris. And again, in 1311, he formulates the same demand, adding “so that nobody from now on may hear quotes, comments or lectures” on writings and opinions of Averroes[42]. Nevertheless, the most pronounced Averroist of the masters of arts was appointed master of the arts students at the Collège de Navarre some years later, notwithstanding the fact that John and his colleagues not only spread dangerous ideas, like a strong lay government, but also considered their profession as master an aim in itself, presenting themselves as professional philosophers mocking those who tried to convert the infidels[43]. The fundamental difference between the two philosophers is symbolized by their appreciation of the city of Paris: whereas Lull abhors Paris, source of perversion of the intellect, John considers that this is the place where real philosophy blossoms[44].

As for John’s Averroism, in fact the core is the way in which he defends from a philosophical perspective the texts of Averroes and to see in them a rational elucidation of Aristotle[45]. He knows these texts intimately and quotes them extensively, but there are not his exclusive reference. He also sometimes discards them or judges them obscure[46]. However, he was considered as the Prince of the Averroists, a qualification he certainly earned.


This is the factual skeleton of his early life and career, before the big change brought about by his close friendship with Marsilius of Padova[47]. Marsilius had come to Paris some years before John entered the college de Navarre. As we saw above, he was rector of the university in 1212-1213. Thus, they were colleagues at the same faculty since several years, and probably close friends, before they were forced to leave the city of Paris in 1326 because of the political treatise Defensor pacis, written by Marsilius (and for a long time considered to be with the involvement of John[48]). The work was published in 1324, but it became public and identified as Marsilius’s work only in 1326. This defence of secular power obviously angered the Pope and when the university itself joined in this indignation, they took refuge with the emperor Louis of Bayern, who was at that time in conflict with the Church and even excommunicated. John and Marsilius would also be excommunicated in 1327. John’s further life – he followed the emperor to Italy, probably assisted to his coronation in Rome, was appointed bishop of Ferrara and personal council of the emperor – was adventurous, but it came to a sad end: on the way from Rome to Ferrara, to access his bishopric, he died accidentally, probably at Montalto, between 10 and 15 September 1328[49].

The period after 1326 will not be the focus of this study. Not only is it a very short period indeed (1326-1328), although fascinating from the point of view of politics, it is also devoid of interest as far as John’s intellectual production is concerned, for we do not know any work written after 1326 (or even 1323). “However, it is possible that Jandun was active at the theological faculty, although he was not a regent master of theology”. The idea that John had actively participated in the writing of the Defensor pacis has been proved false by recent research[50] and his influence on Marsilius has to be reconsidered[51].

On the contrary, the first part of his life, as teacher and commentator at the arts faculty in Paris, is full of interest. In fact, we may consider him as one of the great arts masters of the beginning of the fourteenth century (although Sten Ebbesen has presented Radulphus Brito as “the last of the great arts masters”, in a beautiful article published at the turn of the century[52]). John commented on the great majority of Aristotle’s works[53], omitting the Organon (so he seems not to have taught grammar and logic, which is a remarkable fact[54]). Moreover, he wrote independent treatises and a big number of questions and sophismata (at least ten). He also is the author of at least one poem, on the city of Paris, as mentioned above. He probably studied theology[55]. We do not have specifically theological writings of John de Jandun, but we do have texts of a more theological than philosophical character, for instance the De infinitate vigoris Dei [56].

Relying mainly on the studies of Schmugge[57] and Vella[58], one can give a tentative and abbreviated list of John’s works in chronological order:


Commentary on the Parva naturalia (1309);

Sophisma de sensu agente (1310);

A series of independent Questiones;

Commentary on the Physics (ca. 1315);

A series of Questiones and the Tractatus de sensu agente;

(in 1315 he entered the Collège de Navarre);

Commentary on De anima (1315-1318);

Questio de pluralitate formarum (1317)[59];

Commentary on the Rhetorica (1317)[60];

Commentary on the Problemata (1318);

Commentary on the Economica (1319);

Commentary on the Metaphysica (1319-1320);

Expositio de anima (1321);

De laudibus Parisius (1323).


The Commentaries on De celo, De bona fortuna, and several independent Questiones cannot be dated with precision. Commentaries on the Ethica and Politica have not yet been found[61]. Among the important questiones, we must mention the Questio de pluralitate formarum (1317) and the Questio  de specie intelligibili.


Obviously, further research and the possible discovery of other writings or other versions of his works may change this picture. As it is, we can say that John wrote an amazing number of commentaries and disputed questions in a relatively short time (between 1309 and 1323 or 1324[62]) and that he covered almost the whole curriculum of the arts faculty.


Character of his writings


John’s writings are manifestly the result of lectures at the arts faculty, more or less revised afterwards for their publication. We often find mentions of his students, for instance in an interesting passage of the commentary on the Parva naturalia:


Quidam de scholaribus meis clare intelligentie iuvenis honorandus dicit mihi post exitum scholarum quod si ab albedine imperfecta incipit motus ad magis perfectum […] Tunc ego quesivi ab ipso quid diceret si […][63].


In his redactions John also often points to the difficulty of the problems he treats and stresses the novelty of the subject matter, saying for instance that the question is difficult because it has not been discussed earlier, or that it has been insufficiently treated:


Et scias quod ista questio est bona et difficilis et ab aliis inveni parum ordinatum sufficienter, sed premisso labore non modico congregavi[64].


He sometimes congratulates himself with the solutions he has found (“in hac autem notabili distinctione non parum gaudebat animus meus”; “Et in hac expositione letatus sum cum laude Dei. Sic dictum sit ad questionem de qua parum invenies ab aliis ordinatum”[65]). We can see this kind of sentences as a sign of high self-esteem (which certainly was an aspect of his character, as the quotation above indicates[66]), but at the same time as the simple expression of a certain relief of having found a satisfying solution and of proud to have been able to understand a difficult text better than his predecessors. Sometimes, in the same questions on the Physics, he explicitly leaves his position open to criticism and better arguments[67], a not unusual attitude in philosophical questions of his time[68].

These kind of personal comments are not only present in the early commentaries (on the Parva naturalia and the Physics), written before his nomination at the Collège de Navarre, but also in the later, important commentary on the De anima (the Questiones de anima).

In short, John’s writings represent an impressive output of a rather long career, the career of an arts master interested in Aristotle’s philosophy, the ideas of Averroes and the various conflictual topics resulting from reading Averroes in a Christian world.

It is clear that master John of Jandun highly respected the great authorities of scholasticism, Aristotle and his “Commentator” Averroes, whom he steadily defended against his adversaries. The issue of Averroism has been extensively discussed since many decades, lately for instance by Jean-Baptiste Brenet (Brenet, 2003) and Dag Hasse[69]. I will not enter this intricated field, both for lack of competence and because it is not the purpose of this study. Let us just quote an amusing passage of MacClintock[70]:


Of all the people who have been termed “Averroist” for one reason or another, few have been more anathematized than the 14th-century master of arts John of Jandun. He was cited in his own century as a “heretic and a heresiarch”, as a “son of the devil”, and as an “offspring of malediction”.


This has to be seen in a new light: as noted by Kaluza, more recent historiography has come back from the ‘simplistic’ view of Jean de Jandun as fullhearted Averroist[71] thanks to the discovery of new texts, new versions of the great commentaries, new evaluations of concepts of philosophical Averroism and political Averroism, and along with the general revision of John’s writings – still waiting – the whole context of the first quarter of the fourteenth century should be revised.

Let us also add that because of his ‘dangerous’ ideas and the difficult relations between arts masters and the Church, John had to be careful in order to protect himself from possible condemnations. Thus, he often added at the end of his problematic questions a sentence claiming that according to the doctrine of the Church the answer was different and that he fully adhered to this doctrine, but that explaining Aristotle faithfully, from a philosophical perspective and relying on Averroes, he thinks he has reached a truthful explanation. This is what has been called by MacClintock ‘disclaimers’[72]. An example is found in the third book of his Questiones de anima, where he addresses the demonstrability of Christian faith. I reproduce a passage quoted and translated by Paola Bernardini[73]:


All such things that the Catholic faithful affirm, I affirm are absolutely true without any hesitation, but I do not know how to prove them. Let those who know how to do so rejoice, but I hold them and profess them only as a matter of faith (“sola fide teneo et confiteor”)[74].


Thus, while he systematically draws upon Averroes (here in commenting on the De anima, but also in his other commentaries) and considers his theses as absolutely true, he declares that the Catholic church holds a different view, which he does not know how to prove but to which he adheres from the point of view of faith. This has been called the “double truth”, a concept that has been rejected and criticised, but which is to my eyes a perhaps simplifying but evocative image of the situation.


Style of his works


Let us first state the obvious fact that John of Jandun’s works (apart from the De laudibus Parisius) are traditional in form. They belong to the literary genre of the commentaries[75], mainly in the form of questiones disputate, but sometimes of the expositio (the literary commentary on De anima), or to the genre of isolated disputed questions (or treatises in the form of a disputed question). The relation between the commentaries and the treatises still has to be explored. Sometimes, we come upon an evident link, when the same development is found in a commentary as well as an independent treatise, but in these cases we should establish which of the two is the earlier writing[76].

John writes in a correct style, with fully phrased sentences. He is sometimes even a little ‘garrulous’, in the eyes of some modern scholars. Sometimes the influence of his native French language is visible in colloquial expressions, and sometimes he even refers explicitly to this language.

The way he quotes his sources is interesting[77]. One rarely finds the exact phrasing, which means that he mostly quotes by memory. In many cases, he gives a general reference rather than an exact replication of his source. This applies also to his quotations of Aristotle and Averroes. Sometimes, his phrasing is closer to the Auctoritates Aristotelis, or to the passage in which Albertus Magnus treats the subject. One can find examples in the chapters following below[78].

A constant and fundamental aspect of John’s commentaries is the didactical approach. He wrote almost all his commentaries with the students in the classroom in his mind, eager to explain fully and clearly the difficult texts of Aristotle and his Commentator, even if he also often engages in discussions with other, mostly not namely mentioned, colleagues. At the same time, his commentaries contain interesting and amply discussed doctrinal developments. He was a real teacher and at the same time a brilliant and profound philosopher.




John of Jandun was not as massively admired as John Buridan, but the number of manuscripts in which his writings survive and the complicated manuscript tradition, which remains to be studied thoroughly, show that he was widely read.

As MacClintock has noted[79]: “There is no doubt that Jandun’s influence was very extensive at the two Italian universities (Bologna and Padua), as the large number of manuscripts and editions of Italian origin testifies […]. Jandun’s commentaries (on Aristotle) were read right along with those of Averroes for three hundred years after his death”. He was known at Bologna probably already during his lifetime or at least soon afterwards, as is clearly shown by the commentary of Taddeo of Parma on the De anima (“little more than an abbreviated summary of Jandun’s own questions”), and the presence of questions written by John in some miscellaneous manuscripts from the arts faculty at Bologna[80]. Somewhat later John became to be read also at Padua. Outside Italy, he was known in Germany and Poland[81]. One of the manuscripts of the Bibliotheca Amploniana, containing John’s writings, dates from 1327, still in his lifetime[82]. His influence on the next generation of arts masters in Paris has still to be assessed.


Personality and philosophy


Several scholars have noted that, apart from his veneration of Averroes as the greatest interpret of Aristotle (although not always entirely clear), John was mainly interested in the truth as pursued in natural philosophy, for instance by Albertus Magnus and Robert Grosseteste, and not in the theological approach of Thomas Aquinas[83]. Also, his direct and often very critical remarks about his adversaries have procured him the reputation of an aggressive and arrogant polemist. We will encounter some examples in the course of the following chapters[84].

On the other hand, John acknowledges his debt to Aristotle and Averroes in sometimes humble words, as shown by a passage of his Commentary on the Metaphysics:


Si ergo Aristoteles, qui fuit princeps philosophorum, et Commentator, qui fuit multum propinquus, titubabant de inquisitione questionum difficilium, ergo nos multo magis debemus formidare de huiusmodi inquisitione, cum ad Aristotelem et Commentatorem nos habemus sicut simia defectuosa ad hominem, quia sicut simia imitatur hominem cum defectu, sic et nos Aristotelem et Commentatorem defectuose imitamur[85].


Thus, he compares himself and his fellow commentators to shortcoming apes imitating humans, because he and his contemporaries also imitate Aristotle and his Commentator in an imperfect way. This shows that he is fully aware of the difficulty to understand and interpret these great philosophers of the past.

But the main aspect of John’s personality is perhaps that he considered the profession of arts master as an end in itself. For him the philosophical faculty was equivalent to the other academic faculties (theology, medicine or law) and not just a preparatory education, although he must have studied theology, as we saw above[86]. He apparently was proud of his achieving and of the teaching in his faculty, as we can see for instance in his laudatory (but also ironic) treatise De laudibus Parisius.

So, what was real philosophy in John’s eyes?  John’s idea of philosophy in general has been analysed by Z. Kuksewicz[87] from three aspects: 1. philosophy in relation to faith (discussed in the commentary on the Metaphysics) ; 2. the aim of philosophy (for instance in the prologue to the Physics, but also in Metaphysics I, 1, where he quotes Seneca and Robert Kilwardby); 3. the division of philosophy (prologue of the Physics).

We may underline the fact that he was the only Averroist to propose a division of the sciences, as Kuksewicz has remarked[88]. He included a divisio scientiarum in the preface of two of his commentaries, on the Physics and on the De anima[89]. They are similar, but not identical and they do not contain references to each other, which seems to indicate that in both of them he adapted his idea of the field of the sciences to the situation in which he composed his commentary. In fact, in the case of the earlier commentary on the Physics, his introduction offers a complete overview of the sciences, mainly based on Aristotle’s writings, but sometimes supplemented with those of Albertus Magnus and Averroes, in the cases in which we do not have a treatise of Aristotle[90]. On the other hand, in his introduction to the De anima he offers a short general division of philosophy before going on to the division of natural philosophy.

The presence of these divisions shows that he aimed to have an all compassing view of philosophy. As Kuksewicz remarked[91], no other Averroist devoted so much attention to the concept of philosophy; and he adds that for John philosophy was the complete science of the human being.

To complete this picture, we should mention John’s attitude to  medicine, and in particular to Galen. For instance, on the subject of the inner senses he takes up the controversy with the physicians and amplifies Averroes’ criticism; then, he retraces the explanation of the genesis of the error: Galen was wrong because he identified the intellect with the last of the organic faculties[92]. More in general we may say that John is not reluctant to discuss medical matters – sometimes quoting Averroes’ Colliget and Avicenna’s Canon – but he is also ready to recognise that at some point the subject no longer falls within his competence.

Finally, we can add an unexpected aspect of John’s philosophical views: his acceptance of astrology. In an interesting article, Philipp Nothaft has demonstrated that the anonymous author of an epistolary treatise datable to 1322 was engaged in a heated argument with John of Jandun over the status and rationality of astrology[93]. The treatise is a reaction to a letter of Jandun, surviving, in a fifteenth-century manuscript, for having been appended to the main treatise; in this letter, John assumes a pro-astrological stance. In contrast, the author of the anonymous treatise delivers a severe critique of astrology based almost entirely on philosophical, as opposed to theological ideas[94]. At first site, one would expect the opposite from a rational philosopher, but in his commentary on the Physics, and also in the one on De somno et vigilia[95], John already followed the conventional position about celestial influence.

Let us follow the epistolary sequence, as explained by Nothaft: the letter of the anonymous author is addressed to three unnamed friends; he begins by mentioning “a certain cleric studying in Paris”, who sent him an astrological prognostication or iudicium (of Geoffroy de Meaux) based on a solar and a lunar eclipse. The anonymous author responded to the cleric with a general critique of astrological judgements based on eclipses, which he esteems to be vain and containing no certainty. This provoked the ire of John of Jandun, who responded in a letter dated 28 October 1321, which reached the anonymous author after Candlemas (February 2) of the following year. I quote:


Recolitis nichilominus, ut certa fide teneo, quia vidistis et legistis, quomodo magister quidam in artibus, magis michi reverendus quam ego sibi, nomine magister Iohannes de Ganduno, <litteram> argumentis omnino vacuam, sed blasphemiis et increpationibus ac contumeliis plenam, nec minimum omnium argumentorum meorum solvendo (eius littere seriem hic inferius annotavi de verbo ad verbum) michi rescripsit. Dominus Iohannes enim clerico tradidit, et ipse eam vobis legendo ostendit, ac demum michi misit, quam litteram bene post festum Purificationis Virginis primo recepi. Et nunc ad illam tranquillo animo cum nulla iracundia respondeo per presentes […][96].


Thus the venerable master of arts (“more respectable to my eyes than I to him”), namely master Johannes de Ganduno, wrote back with a letter full of blasphemous and accusatory words, but devoid of any arguments. Then, “Master John gave this letter to the cleric and he showed it to you to read, and then sent it to me”. And in fact, John’s letter contains rhetorical strategies and ad hominem tactics, moreover in a dismissive tone (“Who are you to think yourself smarter than than Ptolemy”, etc.)[97]. John exposes a compromise position that was widely accepted by theologians and philosophers alike (the celestial bodies affected the human body, giving a strong inclination towards one particular course of action) and which is consistent with his statements in the six years earlier commentary on the Physics. However, it is rather disappointing, as the anonymous author rightly remarks, that John here uses a condescending tone instead of refuting seriously his opponent’s arguments[98]. Must we conclude that already in 1321 John was so imbued with his own importance and reputation that he reacted to opponents he esteemed unimportant with contempt rather than with the usual open attitude of discussion?



Purpose of the following chapters


In the following chapters, by approaching John’s literary production from the point of view of intellectual history, I will try to give a tentative picture of his methods and personality. I will focus on literary form, teaching methods, vocabulary, and personal remarks, not on doctrinal aspects in the first place, although they may be mentioned in some cases.

Also, this study is limited to John’s commentaries. The disputed questions and treatises will only occasionally be mentioned in comparison. The commentaries are the following:


  1. Questiones in Parva naturalia (1309)4
  2. Questiones super libros Physicorum ( 1315)
  3. Questiones super libros De celo et mundo (date uncertain)
  4. Questiones de anima (I and II) (1315-1318)
  5. Questiones super librum Rhetoricorum (1317)
  6. Prologus ad Expositionem de problematibus (1318)
  7. Questiones libri Economice (1319)
  8. Questiones in librum De bona fortuna (date uncertain)
  9. Questiones super librum De motu animalium (date uncertain)
  10. Questiones in duodecim libros Metaphysice (1319-1320)
  11. Expositio de anima (1321)


The commentaries are listed here in the probable chronological order (the questions on De celo having been inserted after the Physics because of the usual order in collections of Aristotle’s treatises on natural philosophy). Although many of John’s commentaries present two different redactions and the dates are rarely certain, I decided to treat them in the approximate chronological order, in order to see how their character and style reflect the successive stages in John’s teaching. As mentioned above, several commentaries, as the one on De celo and on De bona fortuna, cannot be dated with precision. Commentaries on the Ethica and Politica have not yet been found[99].

As we see, the important commentaries on natural philosophy have been composed early in John’s teaching career, except the one on the Metaphysics, which follows only after several minor commentaries and almost all his questions and treatises. The suggested date of the questions on the Parva naturalia (mentioned in a colophon) is amazingly early. If correct, maybe this has been caused by internal opportunities or constraints in the faculty of arts.

Finally, I should note that in the discussion of the commentaries I mainly relied on early editions. In some cases, this raises some problems (see the chapter on the De celo et mundo), but I leave the complicated task to study the different editors, like Zimara, and their methods to more competent colleagues.


In the following chapters I will give, for each of the commentaries, a short description, followed by some extracts providing examples. Some commentaries will be treated more extensively, because the topics are more familiar to me; this is particularly the case of the De anima commentaries.

I will quote for each item the corresponding pages in three publications: my repertory of Parisian arts masters (Weijers, Le travail intellectuel, see the Bibliography) indicated here as Repert.), MacClintock’s monograph (MacClintock, 1956), and the study of Schmugge (Schmugge, 1966).



[1] Z. Kaluza (+), in Dictionnaire des Lettres françaises,790-791.

[2] See the Bibliography.

[3] For instance N. Gorochov, Le collège de Navarre de sa fondation (1305) au début du XVe siècle (1418). Histoire de l’institution, de sa vie intellectuelle et de son enseignement, Paris 1997.

[4] The name found in the manuscripts varies, but is mostly spelled as Johannes de Ganduno or Johannes de Genduno (the Latin name of his village being Gendunum); the first form has caused confusion with Johannes de Gandavo, the thirteenth-century theologian, and even with Johannes Dullaert, a fifteenth-century commentator on Aristotle (this is the case for instance in the catalogue of the BnF in Paris) ;  sometimes the name is completed by Remensis, pointing to his diocese of origin (cf. Schmugge, pp. 1-3 ; 130).

[4] Cf. Gorochov, p. 192 ; MacClintock, p. 5 ; Pattin, Pour l’histoire du sens agent, p. 111. The earliest commentary, on the Parva naturalia, probably dates from 1309 (see Chapter 1).

[4] Cf. MacClintock, pp. 6 and 135 (n. 32) where he suggests that the treatise was brought to Paris by Marsilius of Padua (as the passage quoted below seems to indicate); Schmugge, p. 6. Pietro d’Abano finished his Expositio problematum in Padua in 1310. Like Schmugge, Vella suggests as possibility that Pietro d’Abano was one of John’s masters (see A. Vella, Voluntas Aeterna, p. 15).

[7] Schmugge, p. 4 n. 26; Pattin, op. cit., p. 112.

[8] Gorochov, pp. 192-193.

[9] The manuscript is now BnF lat. 6542. The words quoted are on f. 1r, last quarter. Cf. MacClintock, p. 135; Gorochov, p. 193. We will come back to this text below (Chapter 8).

[10] Gorochov, pp.183-184; MacClintock, p. 6; Schmugge, p. 9. Also Pietro da Modena taught at the Collège de Navarre, see Vella, p. 15.

[11] MacClintock, Appendix C, p. 130; Schmugge, Anhang I, p. 120.

[12] Cf. Pattin, p. 111, who says that probably, he had already composed most of his works by then.

[13] An ‘expectation’ gave the recipient the possibility of receiving a canonical prebend at some point in the future. Apparently John had obtained it by 1323. See CUP II, 730 ; Gorochov, p. 194. Thus, he only went to Senlis in 1323, cf. Schmugge, pp. 23-25.

[14] I quote here a letter of William Courtenay(13/01/2024) in response to my questions.

[15] I quote Courtenay again :  « he is among the very few who received an expectation from John XXII at that time, and is listed as a regent master in arts. All those who received an expectation (in response to the first rotulus from the Univ. of Paris or any institution) were a senior group, having been MA for several years and probably an advanced student in theology ». Probably, John obtained a doctorate in theology, as affirmed in a note to CUP II, and if before 1326, this was from Paris. See W.J. Courtenay, Rotuli Parisienses, I, p. 34, and CUP II, 730 p. 718 : « Johannes de Janduno post an. 1316 magisterium in theologia recepit, et an. 1328, Maii 1, ipse ‘Remensis dyocesis, sacre theol. Doctor, consciliarius’ Ludovici Bavari, a Ludovico episcopus Ferrariensis renuntiatus est ». The source quoted is the Vatican Archive, Theiner, Cod. Diplom., and Vatikanische Akten z. deutsch. Gesch. in der Zeit Kaiser Ludwigs d. Bayern, n° 1004. I did not check these documents.

[16] MacClintock, p. 6; Schmugge, pp. 23-24. And see below Chapter 5.

[17] The contract has been published in the Chartularium of the Collège de Sorbonne : P. Glorieux, Aux origines de la Sorbonne II, pp. 544-547 n° 423 ; and cf. n° 352 note 299. It is Hannibal of Ceccano, as provisor of the College, who gives his assent to the renting out of a house in the Cloître Saint Benoît to Nicolas of Vienne and John of Jandun. Cf. MacClintock, p. 6 and 135 (n. 43) ; Schmugge, pp. 25-26. The last suggests that MacClintock is wrong in saying that John will rent the house only after the death of Nicolas. I quote Courtenay again : « John had been living in a house belonging to the Sorbonne for some time, along with Marsilius and Robert de Bardis of the Florentine banking family and future chancellor at Paris. Nicholas of Vienne may have been part of that circle ». Cf. W.C. Courtenay, « Radulphus Brito, Master of Arts and Theology », in Cahiers de l’Institut du Moyen Age Grec et Latin 76 (2005) pp. 131-158.

[18] See below.

[19] W.O. Duba, « Masters and Bachelors at Paris in 1319 : The lectio finalis of Landolfo Caracciolo, OFM », in Th. Jeschke& A. Speer (eds.), Schüler und Meister, De Gruyter, 2016, pp. 315-365, esp. 348-358. See also Chapter 10.

[20] See Duba, op. cit., p. 317.

[21]See also M. Dykmans, « Le cardinal Annibald di Ceccano (vers 1282-1350). Etude biographique et testament du 17 juin 1348 », in Bulletin de l’Institut Historique Belge de Rome 43 (1973) pp. 159-161.

[22] C. Schabel, « The Commentary on the Sentences by Landulphus Caracciolus, OFM », in Bulletin de Philosophie Médiévale 51 (2009) pp. 145-219 (p. 154).

[23] Cf. Schmugge, pp. 21-23 ; Dykmans, pp. 161-164.

[24] Cf. Ch.J. Ermatinger, « John of Jandun in his Relations with Arts Masters and Theologians », in Arts libéraux et Philosophie au Moyen Age, éd. Ch. Wenin, Montréal/Paris 1969, pp. 1173-1184 (here 1177); MacClintock, 26-50, 103-110; Pattin, op. cit.

[25] Cf. Ermatinger, op. cit., p. 1174.

[26] Wylton taught as Master of Arts in Oxford (1288-1304) and as Master of Theology in Paris (c. 1304-1322).

[27] I quote Ermatinger, op. cit., pp. 1182-1183.

[28] Cf. Ermatinger, op. cit., pp. 1183-1184 ; P. Bernardini, Aristotle’s De anima at the Faculties of Arts, 13th-14th Centuries, Turnhout 2023, pp. 22, 170. On his discussion with Wylton, see also Chapter 4, on the Questiones De anima.

[29] Cf. Ermatinger, op. cit., pp. 1180-1181.

[30] Erfurt, Amplon. F. 178 f. 148vb ; quoted by Ermatinger, p. 1181 n. 30.

[31] See the interesting volume edited bv J. Chandelier and A. Robert, Savoirs profanes dans les orders mandiants en Italie (XIIIe-XVe siècle), Ecole française de Rome 2023, and in particular the article of W.J. Courtenay, « Italian Mendicants at Paris in the Fourteenth Century », pp. 533-546.

[32] Cf. R. Saccenti, « Sul concetto di specie. Un dibattito bolognese del XIV secolo attraverso une quaestio di Matteo da Gubbio », in DSTFM 33 (2022) pp. 2049-288.

[33] Op. cit., pp. 250-251. See also G. Fioravanti, « Fare filosofia », in C. Casagrande, G. Fioravanti (eds.), La filosofia in Italia al tempo de Dante, Bologna 2016, pp. 123-161.

[34] Brenet, op. cit., p. 29.

[35] For Maino, see Chapter 4 (Questiones De anima).

[36] MacClintock, pp. 97-98.

[37] MacClintock, p. 97, translating Questiones De anima, f. 86ra.

[38] Cf. P. Bernardini, op. cit., pp. 48-49.

[39] Cf. L. Bianchi, « Johannes de Malignes », in C. Angotti, M. Brinzei, M. Teeuwen (eds.), Portraits de maîtres offerts à Olga Weijers, Porto 2012, p. 306.

[40] Cf. Ch.J. Ermatinger, « Notes on some Early Fourteenth-Century Scholastic Philosophers », in Manuscripta 3 (1959) p. 162. He quotes here a passage of a commentary on the De substantia orbis, by an anonymous author, « probably teaching at the University of Paris at the same time as Jandun ».

[41] The words averroistarum princeps are used by the editor of John’s commentary on De substantia orbis in 1514 ; see Hasse (op. cit. infra n. 61) p. 314 and n. 30.

[42] Gorochov, p. 193.

[43] Gorochov, p. 194. Maybe it was John who made fun of Lull for wishing to convert infidels and who was attacked by Lull in his own classroom. Cf. A. de Libera, Penser au Moyen Age, Paris 20), pp. 134-135. See also R. Imbach, « Lulle face aux Averroïstes parisiens », in Raymond Lulle et le Pays d’oc, Toulouse 1987 (Cahiers de Fanjeaux 22), pp. 261-282 (here 279-280).

[44] Cf. Imbach, op. cit., p. 280 and n. 118. The reference to John’s treatise De laudibus Parisius should be handled with care, because many passages are ironic or even sarcastic.

[45] Brenet, p. 13. Cf. J. Biard, « La noétique de Jean de Jandun et son rapport à celle d’Averroès », dans A. Hasnawi (éd.), La Lumière de l’intellect. La pensée scientifique et philosophique d’Averroès dans son temps, Leuven 2011, pp. 497-506.

[46] Brenet, pp. 15-18.

[47] For this period, see Schmugge, pp. 25-38 ; J. Miethke, De potestate papae, Tübingen 2000, pp. 208-211, 223-235 ; id., “Wirkungen politischer Theorie auf die Praxis der Politik im Römischen Reich des 14. Jahrhunderts”, in J. Canning, O.G. Oexle (eds.), Political Thought and the Realities of Power in the Middle Ages, Göttingen 1998, pp. 173-210; V. Syros, Marsilius of Padua at the Interaction of Ancient and Medieval Traditions of Political Thought, Toronto 2012, pp. 16, 22-24.

[48] Cf. A. Mulieri, « I Filosofi, Maometto e il Concilio. Marsilius da Padova sui legislatori religiosi », in Etica & Politica / Ethics and Politics XXIII (2021) pp. 13sqq.  (here p. 23).

[49] Schmugge, pp. 38, 121-122. But see Vella, p. 16.

[50] Cf. Schmugge, pp. 95-96, 118-119 ; Syros, op. cit. (n. 27).

[51] On this point see Mulieri, op. cit., p. 23sqq.

[52] S. Ebbesen, “Radulphus Brito. The Last of the Great Arts Masters. Or: Philosophy and Freedom”, in Miscellanea Mediaevalia 27 (1999) pp. 231-251.

[53] The attribution of a commentary on the De substantia orbis of Averroes has been proved erroneous.

[54] Or maybe, he lectured on grammar and logic between 1307 and 1309, but never published his lectures.

[55] See above.

[56] To be compared to the quodlibetical question with the same title of Thomas Wylton. See my Repertorium, pp. 98-99.

[57] Schmugge, pp. 128-132.

[58] A. Vella, Voluntas aeterna, pp. 17-18.

[59] Cf. Schmugge, p. 21, who quotes MacClintock, p. 118.

[60] Cf. Dykmans, op. cit., p. 162 and n. 1.

[61] Cf. Schmugge, pp. 45-47. He discusses possible question commentaries on the Ethica and the Politica. The quotations alleging a commentary on the Ethics are very convincing. Aurora Panzica kindly confirmed that she had not found any mention of a possible commentary by John of Jandun on the Meteora.

[62] See above, A sketch of his life.

[63] Questiones super De sensu et sensato, qu. 19; quoted by Schmugge, p. 15 n. 91. See Chapter 5. We note that Peter of Modena was a pupil of John (cf. Brenet, p. 29).

[64] Questiones super libros Physicorum, qu. I, 14 ; quoted by Schmugge, p. 15 n. 93.

[65] Questiones super libros Physicorum, I, 9 and VI, 13 ; quoted by Schmugge, p. 15 n. 94.

[66] See above A sketch of his life and n. 9.

[67] See Schmugge, p. 16 n. 96.

[68] Cf. Weijers, 2013, pp. 139-141.

[69] D.N. Hasse, « Averroistica secta : Notes on the Formation of Averroist Movements in Fourteenth-Century Bologna and Renaissance Italy », in J.-B. Brenet (ed.), Averroes et les Averroïsmes Juif et Latin, Turnhout 2007, pp. 307-331.

[70] MacClintock, p. 2.

[71] See for instance Brenet, op. cit., p. 16.

[72] MacClintock, pp. 65, 69-70.

[73] P. Bernardini, op. cit. (n. 28), p. 170.

[74] Questiones de anima III, 12. John borrows Wylton’s words, as noted by Bernardini, loc. cit. See also W. Senko, « Jean de Jandun et Thomas Wilton ? Contribution à l’établissement des sources des « Quaestiones super I-III De anima » de Jean de Jandun », in Bulletin de Philosophie Médiévale 5 (1963) p. 143 ; A. Alonso, (Expositio de anima), p. 248.

[75] On this point, cf. J. Chandelier, « Le genre du commentaire médical en Italie (XIVe-XVe siècles) », in Ecritures médicales. Discours et genres, de la tradition antique à l’époque moderne, Lyon 2019, pp. 45-71.

[76] See for instance Chapter 4, Questiones De anima.  For the moment, I refer to my Repertory and the account of MacClintock.

[77] For the subject of quotation, see D. Calma, Le poids de la citation. Etude sur les sources arabes et grecques dans l’oeuvre de Dietrich de Freiberg, Fribourg 2010. For the way in which contemporary scholars are quoted, cf. Bernardini, op. cit., p. 48.

[78] I wish to thank Michele Meroni for his careful checking of the references.

[79] MacClintock, pp. 8-9.

[80] For the Metaphysics, cf. R. Lambertini, « John of Jandun’s Question Commentary on the Metaphysics », in G. Galluzzo and F. Amerini (eds.), A Companion to the Latin Medieval Commentaries on Aristotle’s Metaphysics, Leiden 2014, pp. 407-410.

[81] Cf. Schmugge, pp. 41-44 ; Z. Kuksewicz, « L’Influence d’Averroès sur des universités en Europe Centrale. L’expansion de l’Averroïsme Latin », in Multiple Averroès, Paris 1978, pp. 275-281.

[82] Ms. Erfurt, Amplon. 2°336; cf. Schmugge, p. 43.

[83] Cf. Schmugge, p. 16 and n. 101.

[84] For instance in his Questio Utrum contradictoria sint simul vera, cf. Schmugge, p. 20; Weijers, Repert., pp. 100-101.

[85] Questiones super libros Metaphysicorum VI, 10 (see Chapter 10) ; quoted by Schmugge, p. 16.

[86] Cf. id., pp. 18-19.

[87] Z. Kuksewicz, « Jean de Jandun et sa conception de la philosophie », in J. Aertsen, A. Speer (eds.), Was ist Philosophie im Mittelalter, Berlin/New York 1998, pp. 428-434.

[88] Z. Kuksewicz, op. cit.

[89] See Appendix 1.

[90] For instance, Albertus’ De lapidibus et metallis.

[91] Kuksewicz, op. cit., p. 434.

[92] Cf. Bernardini, op. cit., pp. 58-59, whom I quote here.

[93] C.Ph. Nothaft, « Glorious Science or Dead Dog ? Jean de Jandun and the Quarrel over Astrology in Fourteenth-Century Paris », in Vivarium 57 (2019) pp. 51-101.

[94] Both texts are edited in the same article (pp. 72-101); John of Jandun’s letter is to be found on pp. 98-101.

[95] Cf. Chapter 1, the section on De somno et vigilia ; Ch. Grellard, « Le réception médiévale du De somno et vigilia. Approche anthropologique et épistémologique du rêve, d’Albert le Grand à Jean Buridan », in Les Parva naturalia d’Aristote (op. cit. Ch. 1. n. 3), pp. 225, 232-237.

[96] Nothaft, op. cit., p. 73.

[97] Cf. Nothaft, op. cit., p. 58-59.

[98] Ibid., p. 61, and, for instance, p. 100 : « quia si esses Parisius coram multitudine sapientium non nisi derisio sequeretur ».

[99] See above n. 61.



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