Sigério de Brabante

Siger of Brabant (c.1240–c.1284)

Born probably circa 1240 in the Duchy of Brabant, Siger of Brabant studied philosophy in the arts faculty at the University of Paris and became regent master there in the 1260s. Various positions which he defended were included in Bishop Etienne Tempier’s condemnations of 1270 and 1277, and he appears to have fled France when cited to appear before the French inquisition. He probably spent his final days in Italy, and died there before November 1284.

As a professional teacher of philosophy, Siger regarded it as his primary mission to lecture on Aristotle and other philosophers and to present their views on the points at issue. Early in his career he defended some of the positions condemned by Bishop Tempier, but after 1270 he often nuanced his exposition of such views by noting that he was only presenting the views of the philosophers or of Aristotle, or that he was proceeding philosophically in these discussions. Often regarded as a leading Latin ‘Averroist’, he agreed with Averroes that there is only one human intellect, though he eventually reversed his view on this. His personal philosophy is strongly Aristotelian, but with various elements derived from Neoplationism.

On the relationship between essence and existence in created beings, Siger denies that existence is something added to a thing’s essence and holds that the existence of such entities belongs to their essence. He holds that one can demonstrate God’s existence, but insists that Aristotle’s physical argument for a First Mover must be completed by metaphysical argumentation. While denying that human beings in this life enjoy any direct knowledge of the divine essence, he seems open to Averroes’ view that they can reach some knowledge thereof.

1 Life and works

Siger studied philosophy in the arts faculty at the University of Paris and became regent master in that faculty in the 1260s, perhaps circa 1263–5. Some of his views were included in a condemnation of thirteen propositions by Etienne Tempier, Bishop of Paris, in December 1270, and many more were included in Tempier’s much broader condemnation of 219 propositions on 7 March 1277. Little is known about Siger’s final years, but it is certain that in November 1276 he and two colleagues from the arts faculty were cited to appear before the French inquisition in January 1277. Apparently he and the others had already departed from France. He probably spent his final years in Italy and died some time before November 1284, murdered perhaps by a secretary. Although his name has long been associated with the radical Aristotelian movement in the arts faculty at Paris known by some as Latin ‘Averroism’ (see Averroism), he was never found guilty of heresy. Scholars have been intrigued by the fact that Dante Alighieri places him in Paradise, and has Thomas Aquinas introduce him.

Most of his surviving writings date from after 1270. Many of his works were reports taken down by others at his lectures, although some of these were later revised by Siger. Other works were originally composed by Siger himself, and some of these were probably based on prior scholarly disputations. A number are commentaries on works by Aristotle, or in one case, on the Liber de causis, written in the form of questions occasioned by the text (see Liber de causis).

2 Philosophy and religious belief

By Siger’s time at Paris, the faculty of arts had become in fact a faculty of philosophy. This was owing in large measure to the recovery in Latin translation in the twelfth and thirteenth centuries of a large amount of philosophical literature of non-Christian origin originally written in Greek or in Arabic (see Translators). There had been initial reservations and even prohibitions early in the thirteenth century on the part of Church authorities at Paris against incorporating some of this newly available material into teaching in the arts faculty at the University. By 1255, however, the situation had changed to the point where the statutes for that faculty required students to read all the known works of Aristotle. Thus Siger regarded it as his primary mission to lecture on Aristotle and the other philosophers, and gave great weight to them.

Siger did this with such enthusiasm in two early works that some of his positions alarmed Bishop Tempier and were condemned in 1270. Thus in his Quaestio utrum haec sit vera he had accepted the eternity of the human species (and hence of the world) (see Eternity of the world, medieval views of), and in his Quaestiones in Tertium De anima (Questions on Book III of Aristotle’s On the Soul), the view associated with Averroes that the human intellect is only one for the entire human race and exists apart from individual human beings (see Ibn Rushd). Particularly offensive to ecclesiastical authorities was the implication following from this that individual souls are not immortal (see Soul, nature and immortality of the).

In addition to Tempier’s condemnation of these views, Thomas Aquinas sharply attacked the Averroistic and Sigerian defence of the unicity of the intellect in his De unitate intellectus, also of 1270. In subsequent works, when dealing with theologically sensitive issues, Siger became more circumspect and struggled to find a satisfactory resolution for the faith–reason problem. When dealing with points defended by Aristotle or Averroes or other philosophers which contradict Christian teaching, he often remarks that he is simply presenting such positions as the view of the philosophers, or according to the mind of the philosophers, or that he is speaking philosophically. In his final works, especially his Quaestiones super Librum de causis (Questions on the Liber de causis), he moves still further in the direction of religious orthodoxy. In sum, while he never works out a fully satisfactory solution to the faith–reason problem, he appears to be sincere in his repeated protestations of religious belief and in his gradual movement toward more orthodox positions. At the same time, along with other colleagues in his faculty, especially Boethius of Dacia, he strongly defends the autonomy of philosophy within its own sphere, and the right of the philosopher, even though Christian, to draw conclusions from philosophical principles wherever they may lead. If these conclusions contradict religious belief, the Christian, being aware of the fallibility of human reason, should regard the teachings of faith as true. Siger does not defend the ‘double-truth theory’, according to which two contradictory propositions, one taught by philosophy and one taught by faith, could both be true at the same time (see Aristotelianism, medieval).

3 Metaphysics: the science of being as being

Siger is familiar with Aristotle’s description in Metaphysics IV of a science that studies being as being and his contrast between this and more particular sciences which study the attributes of only particular parts of being. Siger also recalls Aristotle’s presentation of three theoretical sciences in Metaphysics VI, physics, mathematics, and a divine science that studies separate and immobile (and divine) entities (see Aristotle). Avicenna denies that God can be regarded as the subject of this science, for he maintains that it belongs to metaphysics and not to physics to demonstrate God’s existence. Since no science can demonstrate the existence of its subject, the subject of metaphysics is not God, but being as being (see Ibn Sina). Averroes affirms that it belongs to physics to demonstrate the existence of the First Mover or God, and that in referring to being as being as the subject of metaphysics, Aristotle really means that its subject is the primary instance of being, or God (see Ibn Rushd). In agreement with Avicenna, Siger holds that the subject of metaphysics is not God but being as being. However, he adopts an intermediary position on the issue of a physical or metaphysical proof of God’s existence. The middle term used by Aristotle to prove God’s existence in his Metaphysics is taken from his Physics (see God, arguments for the existence of).

4 Essence and existence

Much contested during Siger’s time and thereafter was the issue of the relationship between essence and existence in created entities (see Existence). It was generally granted that they are identical in God. To account for the metaphysical structure of finite beings, Aquinas defends a composition of two distinct principles in such beings, an essence and a corresponding act of being (esse), often referred to by others as existence. Giles of Rome defends a seemingly more extreme version of this approach, and by 1276 Henry of Ghent sharply criticizes the real distinction between essence and existence, especially as presented by Giles; he postulates an ‘intentional’ distinction between them, that is, one that is less than real but more than purely mental.

In his Quaestiones in Metaphysicam (Questions on the Metaphysics) Siger asks whether in caused beings existence (esse) belongs to their essence. Against this claim he cites Boethius and Avicenna, and then as a leading critic of distinction between them, Averroes. Among contemporaries he presents Albert the Great as holding that existence is added to a thing’s essence, and rejects this position. Siger presents as intermediary the view of Aquinas (in the latter’s commentary on the Metaphysics) that existence is something added to a thing’s essence, which does not belong to its essence and yet is not an accident but is, as it were, ‘constituted’ from the principles of the essence. Siger agrees with Aquinas that existence is not an accident, but complains about the way he formulates his position. For Siger, if existence belongs to a thing it must either be a part of that thing’s essence, like matter and form, or something composed of those principles, or an accident. For Aquinas to say that it is added to the essence without being any of these is for him to postulate a fourth nature among entities. Siger concludes that the existence of such entities belongs to their essence and is not something superadded. The terms which he now uses to signify essence and existence, ‘thing’ (res) and ‘existing entity’ (ens), do not signify different intentions but rather one and the same essence in different ways, one as potentiality (res = essence), and the other as actuality (ens = existing entity).

In responding to various arguments he had offered for real distinction between essence and existence, Siger notes that one especially moved Aquinas. Everything other than the First Being (God) must be composed. Because created pure spirits lack matter–form composition, they must be composed of essence and esse. To this Siger proposes two responses, though he does not assert the first definitively. First, it is enough to say that things other than God recede from him as pure actuality and are multiplied by approaching potentiality. This suffices to distinguish them from God without postulating different ‘essences’ within them. Second, even if one concedes Aquinas’ claim that to be distinguished from God created entities must somehow be composed, Siger finds it sufficient to appeal to substance–accident composition in created spirits. Even in them, there is a distinction between their substance and the intelligible species they use in thinking.

Interestingly, in his final work, Quaestiones super Librum de causis (Questions on the Liber de causis), while discussing the kind of infinity enjoyed by the First Cause, Siger notes that in created spiritual entities existence (esse) is not limited by matter. Yet their existence is limited to their nature which receives it and is related to it as potentiality to actualization. Perhaps Siger now accepts Aquinas’ position on essence and the act of being.

5 Philosophical knowledge of God

Reference has been made to Siger’s insistence on incorporating Aristotle’s physical argument for a First Mover into metaphysical argumentation for God’s existence. For Siger, one cannot stop with a purely physical proof but must in metaphysics establish the existence of a supreme being which is unique, and which is the cause of being for all other entities. At different points in his Quaestiones in Metaphysicam he attempts to show that the First Mover is the creative cause of all other entities, including separate – that is, immaterial – substances. He also offers a series of arguments to show that there is only one first and uncaused cause (see Causation).

Presupposed for all his reasoning from effects to God as the first cause is Siger’s conviction that in this life human beings do not enjoy a direct knowledge of God’s essence. However, on one occasion in his Quaestiones in Metaphysicam, Siger comments favourably on Averroes’ view that human beings can arrive at some kind of knowledge of the divine essence. Siger himself here suggests that one who is truly expert in philosophy may be able to form an adequate idea of the divine essence. Also in his Quaestiones super Librum de causis he offers a series of arguments for and another series against the claim that the essence of the First Cause can be grasped by the human intellect. Unfortunately, his resolution of this question is missing from the text.

6 Procession of created reality from God

In his De necessitate et contingentia causarum (On the Necessity and Contingency of Causes), Siger presents God as the immediate, necessary and eternal cause of the first intelligence, but as only the mediate cause of other effects. He supports this by appealing to the Neoplatonic axiom that from the one simple being (God) only one thing can proceed immediately. This view is at odds with traditional Christian belief both in affirming the eternal existence and the necessary production of various created realities, and in denying that God is the immediate creator of anything but the first intelligence. However, Siger also states twice in the course of his discussion that this is so according to the mind of the philosophers. Hence he may not have adopted this as his own position, although he does offer a sympathetic presentation of necessary emanation in one version of his Quaestiones in Metaphysicam. However, he clearly rejects the theory of mediate emanation or creation in his Quaestiones super Librum de causis.

7 Eternity of the universe

While their religious faith required Christian participants in this discussion to believe that the world began to be, much disagreement existed concerning whether this could be demonstrated philosophically. Bonaventure, at least as he is usually interpreted, defends this possibility. Aquinas denies that human reason can prove this and in his final treatment of the issue goes so far as to hold that an eternally created world is possible, philosophically speaking. As already noted, in a work written before 1270, Siger defends the eternal existence of the human race. After the condemnation of 1270, when he presents argumentation for an eternal world or some eternally produced creature, he usually qualifies this by saying that this is so according to the mind of Aristotle or according to the mind of the philosophers and is careful not to defend the eternity of the world in his own name. Like Aquinas, he denies that human reason can prove that the world began to be (see Eternity of the world, medieval views of).

8 Unicity versus plurality of the human intellect

In his Quaestiones in Tertium De anima from the 1260s, Siger defends the view that there is only one separate intellect (including both the agent and the receiving or possible intellect) for the entire human race. The agent and possible intellects are two powers of one separate substance, and not two separate substances, as Averroes holds in his Long Commentary on the De anima. After the condemnation of 1270 and Aquinas’ attack that same year, Siger deals with this issue very carefully. In his De anima intellectiva (The Intellective Soul) of circa 1273, after much discussion he declares himself unable to resolve this issue on purely philosophical grounds. He concludes that in such a matter one must follow the teaching of faith. In his final work, his Quaestiones super Librum de causis, he strongly argues on philosophical grounds that the intellective soul is a perfection of each individual human body, and that it is multiplied as are human beings themselves. His position is now perfectly orthodox.