SIGIERI of BRABANT. – Belgian philosopher, perhaps a disciple of Albertus Magnus, a contemporary of S. Tommaso, whose interpretation of Aristotle’s thought he opposed. Little is known about his life. He is first found involved in the university disturbances of 1266 at Paris, as a master in the Faculty of Arts, a member of the Picard «nation», and accused of having resorted to violence.
Around 1270 he must have been the best known of a small group of masters who, because they held that Aristotle ought to be understood in the manner of Averroes, called themselves Averroists (v. AVERROISMO). The thirteen fundamental propositions of this Aristotelian Averroism were the object of a first condemnation pronounced on 10 Dec. 1270 by the bishop of Paris (Chartul. Univers. Paris., I, pp. 486-87). From the same year, and perhaps earlier than this condemnation, appears to date Thomas’s Tractatus de unitate intellectus contra averroistas, which in the Munich cod. lat. 8001, from the beginning of the 14th century, is directed in particular contra magistrum Sagerum, and in the Oxford cod. A. 3. 12, also from the beginning of the 14th century, contra magistrum Sigerum de Barbantia et alios plurimos Parisius regentes anno Domini M. CC. 70.
The conflict between S. and Tommaso may be outlined in these terms: for the latter, Aristotle’s thought agrees perfectly with Christian thought, provided that it is freed from Averroes’s interpretation, «qui non tam fuit peripateticus quam peripateticus philosophiae depravator» (s. Tommaso, De unit. intell., II, 59); for S., on the other hand, Averroes understood Aristotle correctly, and Aristotle’s thought on many fundamental points is in no way compatible with the faith. Sigerian Averroism thus made impossible the concordist aim that the Aquinate had set himself. He insinuated that the Averroists, while sheltering behind their interpretation of Aristotle, secretly, «in angulis», professed the doctrines they attributed to the Greek philosopher. At a meeting of masters convened at Paris on 1 Apr. 1272, in the church of S. Genoveffa, it was resolved, among other things: «Quod si magister vel bachellarius aliquis nostre facultatis passus aliquos difficiles vel aliquas questiones legat vel disputet, que fidem videantur dissolvere, aliquatenus videatur; rationes autem seu textum, si que contra fidem, dissolvat, vel etiam falsas simpliciter et erroneas totaliter esse concedat, et aliter huiusmodi difficultates vel in textu vel in suctoritibus disputare vel legere non presumat, sed hec totaliter tanquam erronea pretermittat» (Chartul. Univers. Paris., I, p. 409). This grave and ill-advised statute placed the masters and bachelors who had to expound Aristotle in great difficulty: whenever they encountered texts or raised interpretative problems «que fidem videantur dissolvere», they were compelled either to engage in controversy against Aristotle and declare «simply false and entirely erroneous» certain of his doctrines, or to pass over them in silence. Nevertheless, S. and his bachelors complied with the decree, declaring whenever they had to discuss heterodox theses that those theses were necessary according to Aristotle’s philosophy, but «simply false» according to the faith; they did nothing, however, to refute them, since their task was that of interpreters of Aristotelian thought, nor did they resign themselves to remaining silent. This perhaps explains the serious schism in the Faculty of Arts between the «para Sigerii» (Chartal., cit., I, pp. 523 and 527) and his opponents. To quell it, the papal legate Simon de Brion had to intervene with his judgment of 7 May 1273, in which many abuses are denounced, but in which, strictly speaking, no mention is made of heretical doctrines.
The accusation of heresy against S. and some of his companions was nevertheless soon whispered, and during 1276 he prudently hastened to return to his homeland. But the inquisitor of France, Simone du Val, followed him to Liège, with a formal summons dated 23 Oct. 1276, in which the following were cited to appear before him at S. Quintin: «Suggerum de Brabancio canonicum sancti Pauli Leodiensis, et magistrum Gossioynum de Capella canonicum sancti Martini Leodiensis, et magistrum Bernerum de Wuulla [l. Nivella] canonicum eiusdem, de crimine heresis probabiliter et vehementer suspectos» (cod. Vat. lat. 3978, f. 82ᵃ-83ᵃ, reported by Fr. Dondaine). The date for their appearance was set for the Sunday after the octave of Epiphany 1277.
Meanwhile, Pope Giovanni XXI, in a letter to the bishop of Paris dated 18 Jan. 1277, declared himself concerned by the proliferation at that University of errors prejudicial to the faith; and the papal intervention hastened the condemnation, by the bishop and the academic authorities, on 7 March 1277. Along with many Averroistic or otherwise heretical propositions, this condemnation even struck at certain theses of S. Tommaso.
It does not seem likely that, after 1276, S. returned to teaching at Paris. From a notice gathered by the continuator of the chronicle of Martino Polono (MGH, Script., XXIV, p. 263), we learn that, «o quod quadam opiniones contra fidem tenuerat, Parisius subsistere non valens, Romanam curiam adit ibique post parvum tempus a clerico suo quasi dementi perfossus perit». This seems to have occurred «nella corte di Roma ad Orbiviero», according to Il fiore, XCII, 9-11, before Nov. 1284, during the pontificate of Martino IV, who was none other than the papal legate in France, Simon de Brion.
For the discovery of S.’s writings, and for a list of them, one should consult the major monograph by Fr. P. Mandonnet, who undertook their publication, and the more recent work of F. van Steenberghen. Yet whereas the former has dealt too harshly with S., more than is appropriate for an unprejudiced historian, the latter has presented a portrait of the Belgian Averroist which, because it is based on the attribution to him of writings that certainly do not belong to him, never corresponds to the truth. Mandonnet saw in S. the wily heretic who, as a philosopher, denies what he affirms as a believer. Van Steenberghen, on the other hand, presents an S. who, initially an Averroist, gradually moderates his original Averroism and ultimately (when?) ends by converting, at least in his principal theses, to Thomism.
It is certain that S. at an initial stage, that is, before 10 Dec. 1270, denied with Averroes that, for Aristotle, the one and 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; Giov. di Baconthorpe, Quodlib., I, q. 1, a. 1). But «postquam vidit decretalem», that is, the decree of condemnation of 10 Dec. 1270, this «venerable doctor» revised his position, seeking to reconcile his interpretation of Aristotle with the episcopal decree (Giov. di Baconthorpe, loc. cit.). His effort may be documented by the Quaestiones super 3ᵃⁿˢ de anima, in the Merton College of Oxford, cod. 292 (unpublished), where (q. 1) the rational soul is a substance or composite form, resulting from the intimate union of the intellect (one and separate) with the
parte vegetativo-sensitiva. Anche le Quaestiones de anima intellectiva, edite dal Mandonnet, ammettono che l'anima intellettiva può dirsi forma dell'uomo in quanto «operans intrinsecus et appropriatus ad corpus» (qq. 3 e 7). Un ulteriore passo innanzi S. sembra aver fatto col Tractatus de intellectu, oggi perduto, ma che si leggeva ancora a Padova alla fine del sec. xv. In quest'opera, scritta in risposta al Tractatus de unitate intellectus di S. Tommaso, S. ritornava al concetto dell'anima umana come forma composta dell'intelletto (unico) e della cogitativa (individuale) e ammetteva che siffatta forma composta possa dirsi sostanziale, inerente al corpo umano e «dans esse homini». Il che non significa affatto evoluzione verso il tomismo, ma interno approfondimento dell'averroismo.
A siffatta dottrina fecero buon viso Tommaso di Wilton, Paolo Veneto (v.), G. Pico della Mirandola (v.), A. Achillini, T. Bacilieri, per qualche tempo A. NIO (v.) Pomponazzi (v.), G. Taiapietra e Antonio Bernardi della Mirandola.
Per il resto, le altre dottrine di S. son quelle accennate nella voce AVERROISMO. Particolare rilievo egli sembra aver dato in un libro De felicitate, anch'esso perduto, alla conoscenza delle sostanze separate da parte dell'uomo e alla teoria averroistica della copulatio dell'intelletto possibile con l'intelletto agente identificato con Dio.
«Magistrum magnum, in philosophia maiorem qui tunc esset Parisius», lo dice Egidio Romano (loc. cit.) che lo conobbe ment'era baccelliere. «Sygerus magnus» è detto pure nel cod. lat. 16.222 della Bibl. nazion. di Parigi (f. 74ᵃ). Dante lo pone nel cielo del sole fra i grandi saggi che illuminarono il mondo cristiano della loro luce, a fianco di Tommaso il quale fa un commosso elogio di lui che fu già suo avversario in terra (Par., X, 133-38).