The passive intellect, also known as the potential intellect or the material intellect, is a term used in philosophy alongside the notion of the active intellect in order to give an account of the operation of the intellect (nous), in accordance with the theory of hylomorphism, as most famously put forward by Aristotle.
Aristotle gives his most substantial account of the passive intellect (nous pathetikos) in De Anima (On the Soul), Book III, chapter 4. In Aristotle's philosophy of mind, the passive intellect "is what it is by becoming all things." By this Aristotle means that the passive intellect can potentially become anything by receiving that thing's intelligible form. The active intellect (nous poietikos) is then required to illuminate the passive intellect to make the potential knowledge into knowledge in act, in the same way that light makes potential colors into actual colors. The analysis of this distinction in is very brief, and it has led to dispute as to what it means.
While Greek commentators such as Alexander of Aphrodisias and Themistius were broadly silent on the active intellect (debate over this would only become heated in the thirteenth-century Christian West in the context of debates over whether Avicenna or Averroes provided the account of the working of the intellect which best cohered with Christian doctrine), they provided a great deal of commentary on the nature of the passive intellect. For Alexander of Aphrodisias, for instance, (who coined the term of the 'material intellect' for this power, a name later taken up by Averroes), the passive intellect was a separate intellect from the active.
Averroes and Aquinas
Later philosophers, including Averroes and St. Thomas Aquinas, proposed mutually exclusive interpretations of Aristotle's distinction between the active and passive intellect. Other terms used are "material intellect" and "potential intellect", the point being that the active intellect works on the passive intellect to produce knowledge (acquired intellect), in the same way that actuality works on potentiality or form on matter.
Averroes held that the passive intellect, being analogous to unformed matter, is a single substance common to all minds, and that the differences between individual minds are rooted in their phantasms as the product of the differences in the history of their sense perceptions. Aquinas argues against this position in the Disputed Questions on the Soul (Quaestiones disputatae de Anima), and asserts that while the passive intellect is one specifically, numerically it is many, as each individual person has their own passive intellect.
- Aristotle, De Anima, Bk. III, ch. 5 (430a10-25).
- Commentarium magnum in Aristotelis De anima libros, ed. Crawford, Cambridge (Mass.) 1953: Latin translation of Averroes' long commentary on the De Anima
- Averroes (tr. Alain de Libera), L'intelligence et la pensée, Paris 1998: French translation of Averroes' long commentary on book 3 of the De Anima
- Catholic Encyclopedia article
- Aquinas, De Unitate Intellectus Contra Averroistas (Latin)
- Aquinas, On the Unity of the Intellect, against the Averroists (English)
- Barrionuevo, "La capacidad productiva del nous (DA, 3.5)" (Spanish)