Passive intellect
The passive 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, in accordance with the theory of hylomorphism, as most famously put forward by Aristotle.
Aristotle's conception
Aristotle gives his most substantial account of the passive intellect in ''De Anima, 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 is then required to illuminate the passive intellect to make the potential knowledge into knowledge in actuality, in the same way that light makes potential colors into actual colors. The analysis of this distinction is very brief, which has led to dispute as to what it means.Interpretations
Greek thoughtWhile Greek commentators such as Alexander of Aphrodisias and Themistius were broadly silent on the active intellect, they provided a great deal of commentary on the nature of the passive intellect. For instance, to Alexander of Aphrodisias 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, 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 Disputed Questions on the Soul (Quaestiones disputatae de Anima), asserting that, while the passive intellect is one specifically, numerically it is many, as each individual person has their own passive intellect.