 |
| Siger of Brabant |
Of Siger’s life, we know very few facts for certain. His exact place of birth remains unknown, as well as the locale and circumstances of his death. (Did he die peacefully in Liege, Belgium, or was he assassinated in Italy at the Roman curia?) Even the chronology of his works is uncertain. Although they are thought to have been written between 1265 and 1277, the precise dates remain conjectural.
Concerning his university career, facts are again unclear. Although it is certain that he never left the faculty of arts for one of the higher faculties (theology, medicine, law), his role in the debates that shook the University of Paris and led to the statutes of 1272 remains the subject of discussion (Putallaz and Imbach 1997 versus Bianchi 1999). At the beginning of his career, he was one of Thomas Aquinas’s most outspoken adversaries, but the question as to what degree he would have abandoned Averroism to adopt Thomist views remains open.
Certain passages seem to support the view that he would have abandoned Averroism, while others are incompatible with this hypothesis (Van Steenberghen and Maurer defend the developmental interpretation, whereas Mandonnet and Bukowski defend the idea that Siger never changed his mind and was the strictest Averroist of his time, a philosopher who could without any guilt subscribe to heretical propositions).
 |
| Van Steenberghen |
All of these often radical oppositions about the interpretation of Siger’s doctrines—whether metaphysical, psychological, ethical, or logical—illustrate the difficulty involved in understanding the complex thought of a Master of Arts who taught in a time as intellectually rich as it was eventful.
Siger was influenced by the famous Dominican theologian Albert the Great, was directly attacked by another famous Dominican theologian, Thomas Aquinas, in his De unitate intellectus, was singled out by the condemnations of 1277 (although many of their propositions cannot be related to any of his works), was taken as a model for John of Jandun, later became one of the most important Averroists in the fourteenth century, and was placed by Dante in paradise beside Thomas Aquinas.
Faced with this abundance of information, one must consider Siger’s texts in themselves by situating them in their context, of course, but also by distinguishing what Siger said from what others say he said.
 |
| Albert the Great |
It is well known that the opponents of a thesis tend to present it in a less than advantageous light to make it seem absurd and, in the Middle Ages, heretical. It is also important to take into account how Siger expresses his ideas.
For example, Imbach (1996) showed clearly that Siger habitually took certain passages from Thomas Aquinas and twisted them from their original meaning to defend a thesis opposed to that of his illustrious opponent. Such a rhetorical procedure should not be surprising in the context of the condemnations. If we follow these methodological principles, we can draw a clearer and more nuanced portrait of Siger.
Principle Philosophical Theses
Siger sought to be a career philosopher. At the end of the thirteenth century, this involved being autonomous from theology and being independent from established philosophical authorities. This stance influenced Siger’s philosophical thought.
 |
| Principle Philosophical Theses |
Siger’s claim that philosophy is independent of theology does not in any way involve a rejection of faith. Rather, it seeks to confine theology to the domain of revelation, where it is the supreme guarantor of truth, and only to where it applies there (Siger 1981/1983, VI, comm. 1).
For example, we know through revelation that the world was created. However, revelation does not tell us whether the world was created in time or out of eternity. To decide this question, we would have to investigate the divine will, which is impossible.
So we have a choice: either to believe the first thesis on the authority of Augustine, although it rests on no rational argument, or to believe, contrary to Aristotle, for whom the world was not created, the second thesis, a conclusion arrived at by means of natural reason (1972a, QTDA, q. 2; 1972a, DEM; 1981/1983, III).
 |
| John of Jandun |
Between Aristotle, who opposes faith, and the theologians, who pretend to demonstrate their thesis in a philosophical manner that is false, Siger proposes an intermediary path that conforms to the demands of both faith and philosophy: creation out of eternity.
Siger sought to be independent of philosophical authorities, including Aristotle, as we have just seen, as well as Averroes. Indeed, he held that the philosopher must demonstrate for himself the proofs of his predecessors and oppose or correct them if they prove to be erroneous (1981/1983, IV, q. 34).
Thus, even in his first work dedicated to noetic (philosophy-of-mind) questions (1972a, QTDA, written before 1270), where he is deeply influenced by Averroes, Siger never supported the monopsychist position that Thomas Aquinas attributed to Averroes, a position according to which all of humanity shares a single intellect. This position would imply that there is no individual thinking, as well as no individual immortality, no corporeal fires of hell, and no resurrection of the body.
 |
| Thomas Aquinas |
The best evidence that Siger rejected monopsychism is Aquinas’s introduction to his criticism of Siger’s doctrine in the De unitate intellectus (On the unity of the intellect; written in 1270): “Some, seeing that on Averroes’s position it cannot be sustained that this man understands, take another path and say that intellect is united to body as its mover” (III, sec. 66).
This view of Siger’s position also explains how, in his last work (1972b, presumably written in 1277), Siger could sincerely declare Averroes’s noetic doctrine “absurd and heretical” without abandoning his previous doctrine (1972b, q. 27). Here too Siger takes a middle path. The intellect is not united to the body like a sailor to his boat (the error of Plato), nor is it united to the body like a mould to wax (the error of Alexander of Aphrodisias).
Rather, the intellect functions intrinsically within the body. Siger held that the intellect is not a unique form completely separate from the body (the position of Averroes according to Aquinas, a position similar to Plato’s, and a position against faith and individual morality).
 |
| De unitate intellectus |
He also held that the intellect is not a multiple form completely immanent to the body (the position of Aquinas and Albert according to Siger, a position similar to Alexander’s, and a position against philosophy). Rather, intellect, according to Siger, is a mixed form, separate from the body in substance, but joined with it in function (1972a,QTDA, q. 7; 1972a, DAI, III and VII; 1972b, q. 26).
With regard to morality, about which he wrote very little, as well as psychology, Siger resolutely defended the thesis that the intellect holds sway over the will (1974, Quaestiones morales; Ryan 1983), a position that many theologians of the time considered to be equivalent to determinism.
In metaphysics, Siger held that there is no real distinction between existence and essence (1981/1983, I, qq. 7–8). He also held that universals, as such, are not substances; they exist only in the soul and are acquired by abstraction from the particular natures of things (1981/1983, III, qq. 15 and 28; 1972a, DEM).
 |
| natures of things |
