De unitate intellectus
| Full title | De unitate intellectus contra Averroistas |
|---|---|
| English | On the unity of the intellect against the Averroists |
| Setting | Paris, second teaching period, c. 1270 |
| Target | The thesis of a single possible intellect for the human species |
| Doctrinal standing | A philosophical-theological opusculum; the individual rational soul as form of the body is later defined Catholic doctrine |
De unitate intellectus is Saint Thomas Aquinas's Parisian treatise against the Averroist claim that all human beings share one possible intellect, written to defend the individual intellectual soul as the form of this man.[1][2]
Paris and a single intellect
In the arts faculty at Paris, interpreters of Aristotle influenced by Averroes taught that the possible intellect is one for the whole human species. If that were true, this man would not understand; an impersonal intellect would understand in him. Personal immortality, merit, and the sense of 'I think' would collapse. Thomas's De unitate intellectus contra Averroistas was written in his second Parisian period to refute that thesis from Aristotle's own text and from the nature of the human act of understanding.
The 1913 Catholic Encyclopedia lists the opusculum among the authentic works. It is a polemical, technical book, not a spiritual treatise. Its genre is a master's intervention in a university crisis. Siger of Brabant and related arts masters are the climate, whether or not every modern identification of an opponent is secure. The thesis refuted is clear even when a name is disputed.[3]
This man understands
Thomas's central claim is that the act of understanding belongs to this individual human being. The intellectual principle is the form of the body, not a separate substance rented by the species. Summa theologiae I, question 76, argues the same conclusion in a less polemical order: the intellect is multiplied with individuals, and it is the substantial form of this man. The opusculum fights for that conclusion on the ground of the Aristotelian commentary tradition.[2]
He also distinguishes the agent intellect from the possible intellect and denies that either, as a human power, is a single immortal substance shared by all. God is one intellect. Human beings are many. An angel is an intellect of another order. Collapsing those is the error. The arguments are philosophical. They are in the service of an anthropology the Church would later speak in conciliar language.
What the Church later defined
The Council of Vienne defined that the rational soul is of itself and essentially the form of the human body. That definition closes any anthropology in which a human being is a body plus a rented intellect that is not his form. It does not quote De unitate intellectus. It does not need to. The treatise and the council meet in the same truth: this man is one substance, a rational animal, whose soul is his form and the principle of his understanding.[4]
Personal immortality, particular judgment, and merit presuppose that same unity. A single species-intellect cannot be baptized, cannot sin, cannot see God as this person's beatitude. Catholic doctrine therefore outranks the Averroist thesis independently of Thomas's pamphlet. The pamphlet remains the classic Latin demolition of that thesis. School opinion here is in unusually close service to what the Church would bind.
Text and later reading
Latin and English presentations of the treatise are available in the ordinary Thomistic corpora. Modern copyrighted translations are cited rather than copied. The Leonine text is the scholarly measure. The work is distinct from questions on the agent intellect in the Summa, though the two are read together.[5]
Later Thomists used the opusculum against any revival of monopsychism and as a control on readings of Aristotle. That use is legitimate. Using it to settle unrelated questions about grace or politics is not. The book is about the intellect and this man. It is enough for a book to win that battle.
References
- Back to citation Thomas Aquinas, De unitate intellectus contra Averroistas — Parisian treatise denying that all human beings share one possible intellect.
- Back to citation occurrence 2.0 Back to citation occurrence 2.1 Thomas Aquinas, Summa theologiae I, question 76 — The intellectual principle as the form of the body and the multiplication of intellects with individual human beings.
- Back to citation Catholic Encyclopedia (1913), St. Thomas Aquinas — Public-domain life and catalogue of Aquinas's works, including the Catena aurea, Sentences commentary, and opuscula.
- Back to citation Council of Vienne, Fidei catholicae — Conciliar definition that the rational soul is of itself and essentially the form of the human body.
- Back to citation Leonine Commission, Opera omnia Sancti Thomae Aquinatis — The Holy See's commission for the critical edition of Aquinas's authentic works.