SIGIERI OF BRABANT. - Belgian philosopher, perhaps a disciple of Albert the Great, a contemporary of St Thomas, with whom he was at odds over the interpretation of Aristotle’s thought. Little is known of his life. He first appears in 1266 amid the disturbances at the University of Paris, a master in the Faculty of Arts, a member of the Picard ‘nation’, and accused of resorting to violence.
Around 1270 he was the most prominent figure in a small circle of masters who, because they held that Aristotle should be understood in the manner of Averroes, called themselves Averroists (v. AVERROISM). The thirteen theses of this most Averroist Aristotelianism were the object of a first condemnation pronounced on 10 December 1270 by the Bishop of Paris (Chartul. Univers. Paris., I, pp. 486–87). From the same year, and perhaps even earlier than this condemnation, is the *Tractatus de unitate intellectus contra averroistas* of Thomas Aquinas, which in the Munich codex lat. 8001 (early fourteenth century) is directed in particular against *magister Sogerus*, and in the Oxford codex A. 3. 12 (also early fourteenth century) against *magister Sigerus de Brabantia* and many others teaching in Paris in the year of the Lord 1270.
The conflict between Siger and Thomas takes shape in these terms: for the latter, Aristotle’s thought is perfectly compatible with Christian thought, provided it is freed from Averroes’ interpretation, and ‘here he was not so much a Peripatetic as a corrupter of Peripatetic philosophy’ (*St Thomas, De unitate intellectus*, II, 59); for Siger, by contrast, Averroes understood Aristotle correctly, and Aristotle’s thought on many fundamental points is in no way reconcilable with faith. Siger’s Averroism thus made impossible the concordist endeavour that the Aquinate had set himself. Thomas insinuated the suspicion that the Averroists, while sheltering behind their interpretation of Aristotle, in secret, ‘in corners’, professed the doctrines they attributed to the Greek philosopher. At a meeting of masters convened in Paris on 10 April 1272 in the church of St Genevieve, it was resolved, among other things, that:
> ‘If any master or bachelor of our faculty reads or disputes difficult questions or matters that seem to undermine the faith, he should be admonished; but if he refutes the arguments or the text when they are contrary to the faith, or even concedes that they are simply false and entirely erroneous, he must not presume to dispute or read such difficulties either in the text or in the authorities in any other way, but must entirely pass over them as erroneous’ (Chartul. Univers. Paris., I, p. 409).
This grave and untimely statute placed great embarrassment upon masters and bachelors who had to expound Aristotle, forcing them, when they encountered texts or raised hermeneutical problems ‘that seemed to undermine the faith’, either to enter into controversy against Aristotle or to declare them ‘simply false and entirely erroneous’.
However, S. and his bachelors conformed to the decree, declaring each time they had to discuss heterodox theses that these theses were necessary according to Aristotle’s philosophy, but “simply false” according to the faith; they did nothing, moreover, to refute them, since their task was to interpret Aristotle’s thought, nor did they resign themselves to silence. Hence perhaps the serious split in the Faculty of Arts between the “pars Sigerii” (Chartul., cit., I, pp. 523 and 527) and its adversaries, which the papal legate Simon de Brion had to quell with his sentence of 7 May 1275, in which many abuses were denounced, though, to tell the truth, no mention was made of heretical doctrines.
The accusation of heresy against S. and some of his companions was nevertheless soon whispered, and in the course of 1276 he hastened cautiously back to his homeland. But the inquisitor of France, Simon du Val, caught up with him at Liège, issuing a formal summons on 23 Oct. 1276, which cited to appear before him at Saint-Quentin “Suggerem de Brabancio canonico sancti Pauli Leodiensis, et magistrum Gossiynum de Capella canonico sancti Martini Leodiensis, et magistrum Bernerum de Wuulla [L. Nivella] canonico eiusdem, de crimine heresis probabiliter et vehementer suspectos” (cod. Vat. lat. 3978, f. 82a-83a, noted by Fr. Dondaine). The deadline for appearance was set for the Sunday after the octave of Epiphany 1277.
Meanwhile, Pope John XXI, in a letter to the bishop of Paris dated 18 Jan. 1277, expressed concern about the proliferation at that university of errors prejudicial to the faith; and papal intervention hastened the condemnation, issued on 7 March 1277 by the bishop and academic authorities, which struck down, along with many averroistic or otherwise heretical propositions, even some theses of St Thomas.
It does not seem likely that after 1276 S. returned to teaching in Paris. A report collected by the continuator of Martin of Poland’s chronicle (MGH, Script., XXIV, p. 263) states that “eo quod quasdam opiniones contra fidem tenuerat, Parisius substistere non valens, Romanam curiam adiit ibique post parvum tempus a clerico suo quasi dementi perfossus perit.” This appears to have occurred “in the Roman curia at Orvieto,” according to Il fiore, XCII, 9-11, before Nov. 1284, during the pontificate of Martin IV, who was none other than the papal legate in France, Simon de Brion.
For the recovery of S.’s writings and a list of them, one should consult the major monograph by Fr. P. Mandonnet, who undertook their publication, and the more recent work by F. van Steenbergen. The former, however, has weighed heavily on S. more than befits an unbiased historian, while the latter has presented a portrait of the Belgian Averroist that, being based on the attribution to him of writings certainly not his own, fails to correspond to the truth. Mandonnet saw in S. the heretic par excellence who, as a philosopher, denies what he affirms as a believer. Van Steenbergen, by contrast, depicts an S. who, an Averroist from the start, gradually mitigated his initial Averroism and, at some point (when?), ended by converting, at least in his principal theses, to Thomism.
It is certain that at first, i.e., before 10 Dec. 1270, S. denied with Averroes that for Aristotle the single, separate possible intellect could be called the form of the human body, so that the proposition “this man understands” is not true; what understands is the intellect, not the man (Egidio Romano, In II Sent., dist. 17, q. 2, a. 1; John of Baconthorpe, Quodlib., I, q. 1, a. 1). But “postquam vidit decretalem,” i.e., the condemnation decree of 10 Dec. 1270, this “venerable doctor” revised his position, seeking to reconcile his interpretation of Aristotle with the episcopal decree (John of Baconthorpe, loc. cit.). Evidence of this effort may be found in the Quaestiones super IIIum de anima, preserved in the Merton College, Oxford, codex 292 (unpublished), where (q. 1) the rational soul is a composite substance or form, resulting from the intimate union of the intellect (single and separate) with the vegetative-sensitive part. The Quaestiones de anima intellectiva, edited by Mandonnet, also admit that the intellective soul can be called the form of man insofar as it “operans intrinsecus et appropriatus ad corpus” (qq. 3 and 7). A further step forward seems to have been made by S. in the Tractatus de intellectu, now lost but still read in Padua at the end of the 15th century. In this work, written in reply to St Thomas’s Tractatus de unitate intellectus, S. returned to the concept of the human soul as a composite form of the (single) intellect and the individuable cogitative faculty, and admitted that such a composite form could be called substantial, inherent to the human body, and “dans esse homini.” This does not mean any evolution toward Thomism, but rather a deeper development of Averroism.
This doctrine was well received by Thomas Wilton, Paul of Venice (v.), G. Pico della Mirandola (v.), A. Achillini, T. Bacilieri, for a time by A. NIO (v.) Pomponazzi (v.), G. Taiapietra, and Antonio Bernardi della Mirandola.
As for the rest, S.’s other doctrines are those outlined in the entry AVERROISM. Particular emphasis seems to have been given in a lost book De felicitate to man’s knowledge of separate substances and to the Averroist theory of the copulatio of the possible intellect with the agent intellect identified with God.
“Magistrum magnum, in philosophia maiorem qui tunc esset Parisius,” calls him Egidio Romano (loc. cit.), who knew him while he was a bachelor. “Segregus magnus” is likewise the appellation in codex lat. 16.222 of the Bibliothèque nationale de Paris (f. 74r). Dante places him in the heaven of the sun among the great sages who illuminated the Christian world with their light, beside Thomas, who delivers a moving eulogy of him who was once his adversary on earth (Par., X, 133-38).