Joseph Kenny

Ibn-Rushd carried to an extremity Aristotle's thought on the human soul, which had undergone considerable development through the Greek commentators, Alexander of Aphrodisias, Themistius, and John Philoponus, and then through the Arab philosophers al-Fārābī, Ibn-Sīnā and Ibn-Bājja. It will be well to summarize these first.


In The Soul Aristotle opens his discussion on the intellect (429a 10 ff.) by referring to "that part of the soul by which it knows and thinks, whether or not it is separable (χωριστός) as a thing or only in thought". He declares that it must be impassive, yet receptive and in potency to forms. It must be unmixed, that is, empty of all forms so that it can receive all forms. Whereas the faculty of sense requires the body, the intellect is separable. It is in act when it knows something, but even then it is in potency to actual thinking or to knowing itself. he intellect knows material things in an immaterial way, separate from their individuating matter. Just as things can exist [in the mind] separate from matter, so what belongs to the intellect is separable. (1)

Aristotle then introduces the agent intellect, which is necessary if knowledge is a kind of passion or reception (429b 26; 430a 10 ff.). As the potential intellect is apt to become everything, the active intellect is constantly apt to activate everything, just like the light of the sun, which makes potentially visible colours actually visible. his intellect is separable, impassive and unmixed, being it act by its essence. When it is separated [from the body] it retains its identity; it alone is immortal and eternal. After death, Aristotle goes on to say, we do not remember, because the passive intellect is corruptible, whereas only the active intellect is impassive, and no intellection is possible without it. (2)

The passages summarized in the above two paragraphs have given rise to much speculation and contradictory interpretations. The first passage concerns what various commentators call the "passive" or "potential" or "material" intellect. In this passage Aristotle clearly presents it as immaterial and capable of separate existence. But at the end of the second passage he seems to say the opposite: that this intellect is corruptible and only the agent or active intellect is incorruptible. Thus the first question is whether both intellects are incorruptible or only the latter.

Another question concerns the agent intellect. Is it a personal power of each human soul, or is it an outside single intelligence for all mankind?

The Greek Commentators

Alexander of Aphrodisias

The earliest of the Greek commentators, who also had enormous influence among the Arabs, was Alexander of Aphrodisias (c. 160-220). In treatment of the passive intellect he first distinguishes, like Aristotle, between the state of potency and the state of act:

The potential intellect, with which we are born, is twofold, each receptive of the other: The one is called and is the materia intellect (for everything that receives something is that thing's matter); the other that comes about through teaching and habituation is the form and perfection of the first. The first is physical and material with regard to whatever it has no experience of; this varies, according as some men are born with a good temperament and others not (in the sense that we say all men have an intellect). The second is acquired and comes later; it is the form and habit and perfection of the physical intellect, not in everyone, but in those who strive and learn, in the way that sciences are learned. (3)

He then further distinguishes the passive intellect's state of act, as Aristotle did, into the state of habitual knowledge (which is present even during sleep) and actual consideration; self-knowledge is present in the latter state. (4)

Regarding the agent intellect, Alexander takes up Aristotle's words that it is apt to activate everything and says that this can only apply to an outside (θύροθεν) cause, "the first cause, which is the cause and principle of being for everything else; it is active also in the sense that it is the cause of being for everything intelligible". Such an intellect, separable, impassive and not mixed with matter, is "the first cause, which is intellect par excellence". (5)

This intellect, which understands [itself], is incorruptible, but not its physical subject [the passive intellect]. For when the soul, of which it is a power, is corrupted, it is corrupted. And when it is corrupted its habitual knowledge should be corrupted along with it; thus the power and its perfection are both corrupted. (6)

Alexander frequently stresses the continuity of sensation, imagination and intellection. (7) Ibn-Rushd was not wrong in interpreting him to say that the passive intellect is only a disposition of the imagination enabling it to communicate with the agent intellect.

Alexander also launched the Platonic idea that the agent intellect, being at the summit of intelligibility, should somehow in itself contain the forms of all things, and thus be the giver of all forms both in the physical world and in the mind. This is opposed to the Aristotelian principle that all knowledge comes from the senses, and that the agent intellect is content-free, having merely the function of abstracting and universalizing sense data.


Themistius, who wrote around 387, was another commentator who had major influence on the Arab philosophers. His treatment of the intellect similarly begins with a distinction between the intellect in potency and the intellect in act. (8) But his interpretation of the intellect in act makes it equivalent to the agent intellect: "It takes hold of the intellect in potency and leads it to act, thus producing the habitual intellect, in which universal notions and sciences abide." (9)

Themistius likens the agent intellect to "a craftsman, who embraces and shapes thoughts when he likes, for it is the maker and supplier of thoughts. Therefore it is most comparable to God, for God is in one way the very things that exist and in another way their provider. (10) It has all forms at once and comprehends them all together. (11)

Themistius affirms that the agent intellect is one for the whole human race, arguing that this is the only way to explain why many people can have the same ideas, since he sees no way that ideas can be individuated. (12)

Several times in the discussion Themistius raises the question whether the passive intellect is incorruptible, and thus whether there is any individual immortality. His solution, contrary to Alexander of Aphrodisias, is that Aristotle's "corruptible passive intellect" means the composite of the passive intellect and the body with its sensitive powers. "The composite is corruptible, passive and inseparably mixed with the body, whereas the intellect in potency is impassive, unmixed with the body." (13)


Writing around 533, Simplicius repeats the common Aristotelian notions on the human soul, but in an obscure style more proper to literature than to philosophy. A few ideas stand out, however, which he does not elaborate on. One is that the agent intellect is "separable" (χωρισθεις), but not "separate" (χωριστός), indicating that it is part of the soul. The passive or "physical" intellect likewise is separable. (14)

It is clear that Aristotle is talking about our soul. In our soul there is not only the passive, but also the active, the principle and cause of what becomes. (15)

As for Aristotle's statement that "the passive intellect is corruptible", Simplicius asks:

How can it be an intellect and be corrupted, if it is immaterial? For every intellect is said to be without matter, and for this reason every intellect is intelligible. (16)

He answers the problem by saying that the passive intellect is corrupted not by going into non-being but by being raised to a higher being by being activated by a separate entity of the soul. (17)

Simplicius, unfortunately, was not known to the Arabs.

John Philoponus

Known to the Arabs as John the Grammarian (YaŒyā an-NaŒawī), John Philoponus wrote in the 6th century. In his treatment of the human intellect he begins by surveying the opinions of his predecessors. Alexander of Aphrodisias distinguished three intellects: (1) the potential, (2) the habitual and (3) the agent, the latter being external and divine. The Platonist Plutarch (46-120) distinguished a different set of three: (1) the habitual intellectsince there is no tabula rasa if all learning is remembering, (2) the intellect in act, (3) an external agent intellect that is sometimes in act and sometimes not.

Ammonius (who wrote around 485) criticised both authors for making the agent intellect external to man; he criticised Alexander in particular for not distinguishing between the essence and the potentiality of the intellect when he said that the intellect is empty of all form before learning; in that case the intellect should be nothing. He criticises Plutarch for Platonizing Aristotle. (18)

Philoponus himself distinguishes three states of the intellect: (1) the potential, (2) the habitual, (3) the actual. (19) He attacks the idea of an external agent intellect, propounded in various ways by Alexander, Marinus, Plotinus and Plutarch, and points out that Aristotle used the word "separable" (), not "separated" (). Nevertheless, in so arguing he eliminated all distinction between the agent intellect and the intellect in act. Thus he has no problem when he says that this alone is immortal and eternal. (20)

Although it is likely they had access to it, Philoponus' work on the soul is never mentioned by Arab writers.

Muslim predecessors of Ibn-Rushd (21)

Al-Kindī (c. 800-866)

The problem facing al-Kindī and the philosophers that followed him was to reconcile the immaterial activity of the intellect with the fact that the soul animates a physical body. If form must be proportionate to matter, and the soul is the substantial form of the body, how can it have an operation that transcends matter? Al-Kindī did not say that the soul is the form of the body, but rather a complete and independent substance, separable from the body, and he praises Plato for this teaching. (22)

In his رسالة في العقل al-Kindī distinguishes four intellects: (1) the intellect which is eternal and always in act; and al-Kindī lets the reader suppose that this is God, although at the end of his الفلسفة الأولى he takes the Platonic position that God is the One beyond any other characteristic, such as intellect; (2) the intellect in potency, which is the human soul in a state of ignorance; note that al-Fārābī denies any distinction between the soul and its powers, whether sensitive or intellective; (3) the intellect which has passed from potency to act, having acquired (مستفاد), intelligible forms through the influence of the first intellect, and having been identified with them; this refers to habitual knowledge; (4) the manifest (ظاهر) intellect manifest, that is, the soul actually considering what it knows.

One can see in al-Kindī echos of Alexander of Aphrodisias and Themistius, especially in positing an extrinsic agent intellect, but al-Kindī never mentions their names, and there are some important differences between the him and them. The same can be said of the other Greek commentators. (23)

Ar-Rāzī (c. 865-925 or 932)

MuŒammad ar-Rāzī was not schooled in Aristotelianism. For him the soul is immortal because it is a complete and immaterial substance. One of five eternal principles, it foolishly fell in love with matter, another eternal principle and man was made. In its present state it needs purification to return to its original state of happiness. (24)

Al-Fārābī (875-950)

Al-Fārābī, like al-Kindī, makes the human soul a substance distinct from the body. He backs this up with a Platonic hylomorphysm, whereby matter is the subject of form, but does not contain forms in potency; rather forms come from an external agent. (25)

Al-Fārābī also articulates a consequence of this dualism, namely that there must be a multiplicity of substantial forms in the same individual, the lower serving as matter for the higher. (26) He says the same about the relationships between the four intellects that he distinguishes. (27) Although in his الدعاوي القلبية he says that man has only one soul, in his فلسفة أرسطوطاليس he clearly opts for the multiplicity of forms or souls in an individual. (28)

Al-Fārābī's four intellects are slightly different from those of al-Kindī. They are: (1) the potential or material intellect, (2) the intellect activated by first principles, (3) the acquired (مستفاد) or educated intellect which makes a person "divine", and (4) the agent intellect; the latter is equated with the Qur'ānic "faithful spirit" (الروح الأمين) and "spirit of holiness"(روح القدس). (29) In hisفلسفة أرسطوطاليس , al-Fārābī says that these stages of the intellect are distinctions of nature (طبيعة) and essence (جوهر). [30]

For al-Fārābī, once a person receives first principles from the agent intellect, he can proceed to further knowledge by himself. (31) But the agent intellect can help the person advance towards happiness, (32) and can be manifest in dreams. (33) The work of the imagination is to prepare the intellect to receive intelligible forms "from the giver of forms". (34) In his تعليقات he speaks of many agent intellects corresponding to the different heavenly spheres, (35) as stated in رسالة في إثبات المفارقات.

In his major writings on سياسة , al-Fārābī says nothing about the cosmic role of the agent intellect. Yet in his رسالة في العقل he says that material forms are given by the agent intellect, (36) while the matter is prepared by the heavenly bodies. (37) In his فلسفة أرسطوطاليس he says that heavenly bodies can have some effect on earthly things, but that only the agent intellect can act on the human intellect, and natural things naturally produce their like. (38)

In his رسالة في العقل al-Fārābī takes up the Plotinian idea that the agent intellect, being fully in act, contains all forms and knows all things, and from it material things derive their existence. (39)

A peculiar teaching of al-Fārābī was that the ignorant, who never advanced beyond first principles, will perish at death like the animals; only by acquiring intelligible forms does the material intellect become intelligible and separable. (40) Yet he has a place in hell for those who knew the truth and did not act according to it. (41) Only in الدعاوي القلبية does he say that each human soul is naturally incorruptible and immortal.

Miskawayh (932-1030)

As other Arab philosophers, Miskawayh held that the human soul is a distinct substance from the body and has only an accidental relation to it. (42) The soul and the intellect are the same thing, and it knows "by its essence". (43) While it moves the body, (44) it is also endowed with self-motion from itself to itself. (45)

Miskawayh repeats the doctrine that our intellect is actualized by an outside intellect which is the first of God's creatures. (46) Elsewhere he speaks of many "agent intellects" corresponding to the heavenly spheres. (47) Although he does no elaborate on the functions of the agent intellect, he does say it is the origin of the first principles of reason which, according to him, do not come from the senses. (48)

Miskawayh anticipates Ibn-Rushd in speaking of the unicity of the soul or intellect for all men. (49) Yet elsewhere he talks of the pleasure the separated soul has in the company of other souls like itself. (50)

Ibn-Sīnā (980-1037)

Ibn-Sīnā, more emphatically than his predecessors, insisted that the soul is a complete substance separate from the body, (51) even though he sometimes said that the soul is "the form" of the body by which it exists and acts. (52) Yet, contrary to al-Fārābī, he denies multiple substantial forms. (53)

Ibn-Sīnā is in agreement with al-Fārābī on the division of four intellects: (54) (1) the material intellect which, like prime matter, lacks all form; it is also called "the passive intellect". (55) (2) the habitual intellect which knows first principles and what can be derived from them, (3) the perfected or "acquired" (مستفاد) intellect, (4) the agent intellect, which is extrinsic.

As for the role of the agent intellect, Ibn-Sīnā goes much farther than al-Fārābī. For him the agent intellect gives existence to human intellects, to all souls (with the dispositive help of the heavenly bodies) (56) and to the four natural elements. (57) It possesses all intelligible forms, (58) and impresses them on the human intellect "by a divine emanation", according to the disposition of the intellect to receive this emanation. (59) It is not God, because it produces multiple effects, whereas God, the One, can produce direcly only one effect, and that is the first created intellect. (60)

Normally Ibn-Sīnā identifies the agent intellect with the intellect governing the lunar sphere, which is the "spirit of holiness" and the angel Gabriel, (61) or the "preserved tablet" لوح محفوظ, Qur'ān 85:22). (62) Yet sometimes he applies the term to separated substances in general, the angels, or the eight intelligences governing the heavenly spheres, (63) or to the first intellect, that God created directly. (64)

Although Ibn-Sīnā says that knowledge of material things comes by a process of abstraction from sense knowledge. (65) he insists that first principles, such as "the whole is greater than its parts", cannot come from sense experience, because they are too certain and universal; so they must come from a "divine emanation". (66)

A peculiar position of Ibn-Sīnā is that habitual knowledge is not really knowledge, and nothing is retained but a disposition to receive intelligible forms when one is actually thinking. Whereas the habitual state is caled "intellect in act" العقل بالفعل, the actual state is called "the acquired intellect" (العقل المستفاد). (67)

Ibn-Sīnā is not consistent in his many lists of four intellects. The division of the intellects in الشفاء, which follows al-Fārābī, more or less, was revised in his other works. The رسالة في الحدود and the رسالة في العقول change the order, and النكت والفوائد في العلم الطبيعي makes another change. Then أحوال النفس ,عيون المسائل ,عيون الحكمة and رسالة في إثبات النبوة reduce the intellects to four, just as they were presented by al-Kindī. (68)

الشفاءرسالة في الحدود/العقولالنكتThe others:
Material intellect material material material
intellect in act habitual habitual habitual
habitual intellect in act acquired in act
acquired/holy intellect acquired in act ---
agent intellect multiple agents agent agent

The رسالة في العقول clarifies that the different intellects (except the agent intellect) are only different states (أحوال) of the speculative intellect. (69)

In رسالة في إثبات النبوة, Ibn-Sīnā explains that the agent intellect gives first intelligible principles directly, but further knowledge comes by reasoning. (70) The agent intellect is also at work by special inspiration, especially prophecy, whether in dreams or when one is awake. (71)

Because he confuses the intellect with the soul, Ibn-Sīnā says that it knows "by its essence". (72) The same confusion is found in الرسالة العرشية, where Ibn-Sīnā compares God's knowledge of himself with the soul's knowledge of itself. (73)

Ibn-Sīnā rejects al-Fārābī's opinion that those who do not know philosophy are annihilated at death, but, in agreement with Themistius, the intellect, as a receptacle of intelligible universal forms which operates without a bodily organ, must of itself be immaterial and immortal. (74) Ibn-Sīnā also argues from a psychological hypothesis that if the soul were to be deprived of all exterior sensation (he is forgetting about the activity of the internal senses) it would still know its own activity and existence. (75) Thus, although it has a beginning with the beginning of the body, the soul cannot cease to exist (76) and, for reasons he cannot fully understand, will retain its individuality after death. (77)

Ibn-Sīnā thus rejects re-incarnation, which is held in different ways by oriental traditions, Greek philosophers such as Plato and Pythagoras (in a metaphoric sense), and those who believe in the resurrection. (78) In رسالة الصلاة he explicitly denies the possibility of the resurrection or immortality of the body or non-rational soul. Afraid of the repercussions of this position, at the end of this work he warns the reader not to divulge what he reads. (79)

In his كلمات الصوفية, Ibn-Sīnā quotes Qur'ānic verses (89:27-28; 70:4; 54:55; 33:44; 22:48; 75:30, 12; 53:8) to show that it is the soul alone, without the body, that appears before God. (80) Nevertheless, in the Ąūfic work العلم اللدني he bows to orthodoxy: "The rational soul... awaits its return to the body on the day of resurrection, as Revelation states." (81) Yet he sticks to his original position in الرسالة الأضحوية في المعاد, where he presents many arguments: If the world is eternal, the earth could not contain the infinite number of people. If human happiness is spiritual, it would be a punishment to send the soul back to the body. The resurrection has to be to a new body, and that is reincarnation, while the matter of the old body must have been shared by many people. How can Christians preach the resurrection and and the same time reject bodily pleasures in heaven? (82)


In رسالة الاتصال Ibn-Bājja continues in the tradition of al-Fārābī in maintaining that the majority جمهور of people who have only sensible or material knowledge, as well as the natural scientists (طبيعيون) who only go as far as knowing forms abstracted from sensible matter, will have no future life. This is reserved for those who are in contact with the agent intellect through knowledge of metaphysics and not by the deceptive phantasies of the Ąūfīs. (83)

Without any apparent knowledge of Miskawayh, Ibn-Bājja asserts that the intellect of this elite is numerically one. Its apparent multiplicity comes from its being related to many different material subjects. (84) The "acquired intellect" (العقل المستفاد) is the human intellect perfected by certain knowledge and is always in act. In fact, there is no distinction between this intellect and the agent intellect, and there is no place for a passive intellect, unless one means by this the imagination. (85)


The philosophical novel حي بن يقظان teaches that the intellect, apart from the body, is the essence of man. (86) At the end of the book Ibn-Ćufayl affirms the unicity of the human intellect for all mankind. (87)

He also speaks of "the spirit or intellect which always emanates from God, like the light of the sun always shining on the world". (88) This sounds like the "agent intellect" of previous philosophers, but in Ibn-Ćufayl's system of universal monism it must rather refer to the single intellect common to angels and men, if not to God also.


Besides his short (جوامع), middle (تلخيص) and long (شرح) commentaries on Aristotle's The Soul, Ibn-Rushd wrote several short treatises on the subject. Since there are some points of divergence from one work to another, it is important to determine their chronology. That is not easy, especially since the small commentary and likely other works went through later revisions. What we do know is that where the تفسير ما بعد الطبعية takes up the subject, (89) it refers to his كتاب النفس, presumably the شرح. The appendix of his جوامع also refers to the شرح. In these works we can discern three stages in the development of Ibn-Rushd's thought.

First, in his جوامع Ibn-Rushd insists that whatever is intelligible, in so far as it is intelligible, is eternal and incorruptible, but he rejects the theory of Plato that intelligible forms pre-exist in us and that learning is only recalling. All knowledge comes from sense experience. Ibn-Rushd asks how intelligible forms can be received by corruptible man and how they can be multiplied according to the multiplicity of persons. He answers that intelligible forms have a formal aspect which is single and eternal, and a material aspect by which they can be received by many men. What is the precise aspect of man that makes him capable of receiving intelligible forms? It is not the body, which can receive only bodily forms; nor is it an intellect in so far as the intellect is in act. Ibn-Rushd concludes then that it must be the soul and, among the powers of the soul, the imagination with its sensory images. This preparation (استعداد) of the imagination is the "material intellect" as far as being (وجود) is concerned, but as for potentiality to receive intelligible forms this preparation constitutes emptiness, which is a requirement for the reception of intelligible forms. In receiving intelligible forms, the material intellect becomes the "habitual intellect" (العقل بالملكة, which in turn becomes the "intellect in act" (العقل بالفعل) when one is conscious of these intelligible forms. The "agent intellect" actualizes the material intellect; it is also called the "acquired intellect" (العقل المستفاد) when the material intelect is in union اتحاد or contact اتصال with it. The word مستفاد is used because we benefit (نستفيد from it. (90)

Secondly, in the شرح Ibn-Rushd rejects the opinion attributed to Alexander of Aphrodiaias, which he accepts in his جوامع, that the material intellect is a disposition of the imagination. (91) He says that the agent intellect and the material intellect are both eternal, incorruptible and single for all humanity. The two come into contact with each person through the phantasies of the imagination which the agent intellect makes intelligible to the material intellect. By means of these phantasies which it makes intelligible, the agent intellect becomes in a way the form of the material intellect. It is in relation to these phantasies that the material intellect is multiple in humanity, and that is why each individual has his own knowledge and goes through a process of learning. But, since the imagination is corruptible, the intellect in act (which he here calls the "acquired" or "speculative" intellect) is corruptible, along with all individual knowledge. But the material intellect continues to be actualized by the agent intellect in other individuals, since the human race exists for all time. (92)

In the same شرح Ibn-Rushd seems to incline towards the opinion of Ibn-Sīnā that first principles of reason are infused directly by the agent intellect. (93) Ibn-Rushd also raises the question whether the material intellect can know separated substances. After a long discussion of opinions, he accepts the principle that the material intellect can know all that is intelligibe, and that can be realized by a contact with the agent intellect. (94)

The appendix to the جوامع refers the reader to the long commentary and corrects his having supported the opinion of Alexander of Aphrodisias that the material intellect a preparation of the imagination. He blames Ibn-Bājja for leading him astray on this point. He now says that the material intellect is an eternal substance and that the imagination only supplies the objects of knowledge. (95)

Thirdly, in the تلخيص كتاب النفس, which is the latest, Ibn-Rushd explains that the material intellect has no physical passivity (انفعال), but that it can receive (قبول) intelligible forms. (96) He rejects the opinion of Alexander of Aphrodisias that this intellect or preparation to receive (استعداد) is something in the human soul, and says that it has to be in a subject of the same genus as the intelligible forms, that is, in a separated substance. But, as other commentators say, this preparation is not of the nature of a separated substance, but pertains to it only in so far as it is in contact (اتصال) with man.

It is clear, then, that the material intellect is something composed of this preparation in individuals and of the intellect which is in contact with this preparation. In so far as it is in contact with individuals it is an intellect in preparation (مستعِدّ) and not an intellect in act. It is an intellect in act in so far as it is not in contact with this preparation. And this intellect is precisely the agent intellect. (97) Thus, in accordance with Ibn-Bājja, whom Ibn-Rushd praises in his جوامع, (98) there is no need for a passive intellect distinct from the single agent intellect for all humanity.

This same position is assumed in the شرح ما بعد الطبعية, where Ibn-Rushd explicitly says that the material intellect and the habitual intellect are corruptible. (These then must be equivalent to the imagination.) The agent intellect is distinct from the material intellect, but it comes into contact with it. By an act which is distinct from its essence, the agent intellect makes sensible forms intelligible; in this way an eternal intellect comes to know corruptible things. But when a man becomes perfect he loses all that is potential and has no other act than that of the agent intellect. "That is ultimate bliss." (99)

According to the تلخيص كتاب النفس, all knowledge comes from the agent intellect through the imagination, even first principles, contrary to the opinion of Ibn-Sīnā. (100) On self-knowledge Ibn-Rushd says:

Speculative knowledge is exactly the same thing as what is known... But that is fully true only of separated things, where the intellect and the intelligible are one in every respect. But in the case of our intellect they are accidentally one. That is, since the essence of our intellect is only knowledge of what exists apart from itself, it knows its own existence accidentally when it knows things outside its essence. That is because its essence is only knowledge of things outside its essence, which is the opposite of separated substances which know outside things by knowing their own essence. (101)
Intellection occurs when the agent intellect illumines the phantasms of our imagination, making them intelligible in act. The agent intellect thus produces in us "a likeness (شبيه) of what is in its own substance," giving us a habit (ملكة) enabling us to know actually whenever we want. This agent intellect, which is our last form, does not exist and know from time to time, but has always existed and will always exist. If it departs from the body it cannot die. It is precisely this intellect which knows (يعقل) when it is joined (عند انضمامه) to the material intellect. But if the material intellect departs from the body it can know nothing of what goes on here. Therefore after death we remember nothing that we knew when it was in contact with the body. When it is in contact with us, it knows intelligible forms here, but if it departs from us it knows its own essence. But whether it can know its own essence while it is in contact with us is another question.
We should realize that Themistius and most commentators are of the opinion that the intellect which is in us is composed of an intellect which is in potency and an intellect which is in act, that is, the agent intellect. In so far as it is composed it does not know its own essence, but it knows things that are here when it is joined to imaginary forms (معان). But when these forms are corrupted it accidentally happens (يعرض) that intelligible forms are corrupted and that oblivion and error follow. (102)

Thomas Aquinas' critique

While much indebted to the philosophers mentioned above, Thomas differed from them on some vital points. The first was their dualistic view of the body and soul as separate substances. This dualism came from their inability to reconcile two facts: (1) if the human soul is the substantial form of a body it must be material, and (1) that intellection is an operation that transcends matter, and its subject cannot be material, since potency and act must correspond.

Thomas faced this problem first of all by distinguishing the substance of the soul from its powers, just as its powers are distinct from their habits and acts. For him a single soul is the substantial form of the body; by its vegetative powers it is the source of the vital functions of the body; by its sensitive knowing and appetitive powers it is the source of its animal functions, and by the passive and active intellects and the will it carries out its properly human activities.

The possibility of the same subject carrying out both material and spiritual activities is founded in another relationship of potency to matter, that of the composite of matter and form to existence, which is its act. Normally existence is the act directly of the composite. But in the case of man, Thomas says that it is the act directly of the form or soul, and indirectly of the matter or body. Thus the soul is capable of existence separate from the body, but while being joined to the body as its substantial form the body shares in its existence. (103)

Another area where Thomas sharply differed from these philosophers was his position that the passive and active intellects are individual powers of each person. (104) Against Ibn-Sīnā, Thomas held that man retains habitual knowledge. Yet he admits the possibility, besides knowledge derived from sense experience, of receiving divine or angelic inspiration.

As for the origin of the soul, Thomas agrees with Ibn-Sīnā, against Ibn-Rushd and others, that it is created with the body. (105)

Concluding note

The Arab philosophers, in the Platonic tradition, were right in looking to heaven for inspiration, since divine and angelic communications are part of human experience. Yet they were supremely deluded in believing in a moon-spirit which functioned as the agent intellect for the whole world. Their dream, however, has been paradoxically fulfilled in man-made communication satellites which beam down digitalized sound, pictures and intelligence to anyone with a receiver.

1. avpaqe.j a;ra dei/ ei=nai, dektiko.n de. tou/ ei;douj kai duna,mei toiou/ton avlla mh. tou/to..))) avna,gkei a;ra, evpei. pa,nta noei= avmigh/ ei=nai))) to. me.n ga.vr aivsqhtiko.n ouvk a;neu sw,matoj) o` de. cwristo,j) o]tan d v ou]twj e]kasta ge,nhtai w`j evpisth,mwn le,getai o` katV ene,rgeian))) e;sti me.n kai. to,te duna,mei pwj( ouv mh.n o`moi,wj kai pri.n maqei/n h' eu`rei/n\ kai. auvto.j de. auvto.n to.te du,natai noei/n))) kai. o]lwj a;ra w`j cwvista. ta. pra,.gmata thj u]lhj( ou]tw kai. ta. peri. to.n nou/n)

2. kai. e;stin o` me.n toiou/toj nou/j tw/| pa,nta gi,nesqai( o` de. tw|/ pa,nta poiei/n( w`j e]xij tij( oi[on to. fw/j\ tro,pon ga,r tina kai. to. fw/j poiei/ ta. duna,mei o;nta crw,mata evnergei,a|))) cwrisqei.j d v evsti. mo,non tou/q v o[per evsti,( kai. tou/to mo,non avqa,naton kai. avi<dion $ouv mnhmoneu,omen de,( o]ti tou,to me.n avpaqe,j( o` de. paqhtiko.j nou/j fqarto,j%( kai. a;neu tou,tou ouvqe.n noei/)

3. De Anima in Commentaria in Aristotelem Graeca, Supplementum II (Berlin, 1887), pp. 81-82:
o` de duna,ei nou/j( o[n e;contej gino,meqa, ditto.j o;n kai. auvto,j( e`ka,teroj e`kate,rou dektiko,j( u`liko.j nou/j kalei/tai te kai. e;sti $pa/n ga.r to. dektiko,n tinoj u[lh evkei,nou%( o` de. dia. didaskali,aj te kai. evqw/n evggino.monoj ei;doj evkei,nou te kai. evntele,ceia) kai. o` me.n fusiko,j te kai. u`liko.j evn pa/sin toi/j mh. pephrome,noij* te.n diafora.n e;cwn* kaqo,son oi` me,n eivsin euvfue,steroi tw/n avnqrw,pwn( oi` de. avfue,steroi $kaqV o] kai. le,gomen pa,ntaj avnqrw,pouj nou/n e;cein%( o` de. evpi,kthto,j te kai. u[steron evggino,menoj* kai, ei/doj kai. e[xij w=n kai, teleio,thj tou/ fusikou/( ouvketV evn pa/sin( avllV evn toi/j avskh,sasi,n te kai. maqou/sin( o[n tro,pon kai. evpi. to/n evpisthmw/n e;cei)

4. Ibid., pp. 82-87.

5. Ibid., p. 89: o` toiou,toj nou/j to prw/ton ai;tion( o] aivti,a kai. avrch. tou/ ei=nai pa/si toi/j nooume,noij))) toioun de. o] de,deiktai u`pV VAristote,louj to. prw/ton ai;tion o] kai. kuri,wj evsti. nou/j)

6. Ibid., p. 90: o` nou/j a;ra o` tou/to noh,saj a;fqarto,j evstin( ouvc o` u`pokei,meno,j te kai. u`liko,j $evkei/noj me.n ga.r su.n th|/ yuch|/ h==j evsti du,namij( fqeirome,nh| fqei,retai( w|- fqeirome,nw| a'n kai. h` e[xij te kai. h` du,namij kai. teleio,thj auvtou/%)

7. Cf. ibid., pp. 76, 79.

8. De Anima, in Commentaria in Aristotelem Graeca, 5 (Berlin, 1900), pp. 95-98.

9. Ibid., p. 98: o`j ekei,nw| sumplakei.j tw|/ duna,mei kai. proagagw.n auvton. eivj evne,rgeian to.n kaqV e]xin nou/n avperga,zetai( evn w|- ta. kaqo,lou noh,mata kai. ai` evpisth/mai)

10. Ibid., p. 99: to. de. w`j tecni,thj\ evpV auvtw|/ ga.r o[te bou,letai nh,mata perilabei/n kai. morfw/sai\ poihtiko.j ga.r auvto.j kai. avrchgo.j tw/n nohma,twn) dio. kai. qew|/ ma,gista eoike\ kai. ga.r o` qeo.j pw.j me.n auvta. ta, o;nta evsti.( pw.j de. o` tou,twn corhgo,j)

11. Ibid., p. 100: pa,nta e;contos avqro,wj ta. ei;dh kai. a[panta a[ma probeblhme,nou)

12. Ibid., pp. 103-104.

13. Ibid., p. 105: o` me.n koino.j kai. fqarto.j kai. paqhtiko.j kai. avcw,ristoj kai. tw|/ sw,mati memigme,noj( o` duna,mei de. avpaqh.j kai. a;miktoj tw|/ sw,mati kai. cwristo,j

14. De Anima, in Commentaria in Aristotelem Graeca, 11 (Berlin, 1882), p. 245.

15. Ibid., p. 247: dh/lon w`j peri. th/j h`mete,raj hvrwthme,non yuch/j\ evn th|/ h`mete,ra| yuch|/ ouv to. pa,scon evsti. mo,non avlla. kai. to. poiou/n( avrch. kai. ai;tion tw/n gignome,nwn)

16. Ibid., p. 247: pw/j nou/j w=n kai. evkei,noj fqei,retai( ei; ge a;uloj kai. evkei/noj\ pa/j ga.r nou/j a;neu u[lhj ei=nai hvxi/wtai( kai. dia. tou/to pa/j me/n nou/j ei=nai nohto,j)

17. Loc. cit.: w`j ei=nai fqora.n tou/ paqhtikou/ nou/ ouvk eivj to. mh. o'n e;kstasin( avllV eivj to. kreittoknwj o'n sunai,resin th/j cwrisqei,shj yucikh/j)

18. De Anima, in Commentaria in Aristotelem Graeca, 15 (Berlin, 1897), pp. 517-520.

19. Ibid., p. 520.

20. Ibid., pp. 534-541.

21. Ibid., For the editions used in this section, see my Philosophy of the Muslim world on this site.

22. رسالة في أنه جوهر لا أجسام، رسالة في القول في النفس المختصر من كتاب أرهسطو وفلاطون وسائر الفلسفة، كلام في النفس مختصر وجيز

23. Cf. Jean Jolivet, L'intellect selon Kindī (Leiden: Brill, 1971).

24. Cf. Majid Fakhry, A history of Islamic philosophy (London: Longman, 1983), pp. 101-102.

25. مبادئ آراء , 16, 19 (p. 33).

26. Ibid., p. 34, 21.

27. Ibid., 27, p. 58.

28. Nn. 75-76.

29. Cf. مبادئ آراء, 22 & 27 (p. 58); السياسة المدنية, 32:6, 36:1, 55:5, 79:9 ff.; رسالة في العقل , nn. 17, 18, 31, 32-40.

30. Nn. 90-93.

31. جواب مسائل سئل عنها, n. 28.

32. Cf. فلسفة أرهسطوطاليس, 98.

33. تعليقات, n. 52; cf. إحصاء العلوم, ch. 3, p. 103, on "practical astrology".

34. تعليقات, n. 53.

35. تعليقات, n. 78, n. 2.

36. N. 38, 42.

37. رسالة في العقل, n. 49; cf. زينون الكبير اليوناني, text with translation by J. Kenny in Orita, 28 (1996), pp. 50-60. Also on this site.

38. N. 99.

39. N. 37. I omit كتاب مقالات الرفيعة في عصول علم الطبيعة from consideration here, because I consider it inauthentic.

40. مبادئ آراء, 32 (p. 67); السياسة المدنية, 82:16; رسالة في إثبات المفارقات; تعليقات, n. 51, 54.

41. مبادئ آراء, 32 (p. 68).

42. مقالة في النفس والعقل, pp. 50, 21-20; الفوز الأصغر, p. 64; فصل آخر من كلامه, p. 195.

43. الفوز الأصغر, 75-81.

44. رسالة في جوهر النفس, p. 197.

45. في إثبات الصور الروحانية, p. 200; في إثبات ذلك أيضاً, p. 201.

46. مقالة في النفس والعقل, 62-61; الفوز الأصغر, p. 87.

47. رسالة في اللذات والآلام, p. 68.

48. مقالة في النفس والعقل, pp. 64, 49; الفوز الأصغر, p. 126.

49. رسالة في النفس والعقل, pp. 55-54.

50. الفوز الأصغر, p. 105.

51. أحوال النفس, ch. 1; رسالة في الكلام على النفس الناطقة, one of Ibn-Sīnā's late works which sums up الشفاء: النفس, m. 5 f. 1-2 & m. 5, f. 4 (= أحوال النفس، 9) ; كلمات الصوفية, 158-160; رسالة في بيان المعجزات والكرامات والأعاجب, p. 404; الشفاء: النفس، مقالة 5 ، فصل 2, الرسالة الأحضوية في المعاد, 141-151; الرؤية والتعبير، فصل أ, p. 274; cf. also العلم اللدني, p. 187-188; النكت والفوائد في علم الطبيعة, pp. 158-161; الرسالة في السعادة, pp. 12-13.

52. مبحث عن القوى النفسانية, ch. 2.

53. الشفاء: النفس، مقالة 1، فصل 3; مقالة 5، فصل 7; أحوال النفس, ch. 11.

54. أحوال النفس ch. 2; عيون المسائل 21; عيون الحكمة p. 37-38; رسالة في إثبات النبوة pp. 43-44.

55. أحوال النفس, ch. 12.

56. See also تعليقات, p. 41.

57. عيون المسائل 9; مبحث عن القوى النفسانية ch. 3, says that soulss (of all kinds) come "from without".

58. أحوال النفس ch. 12; مبحث عن القوى النفسانية, ch. 10.

59. Ibid., 39.

60. النكت والفوائد في العلم الطبيعة 166-167.

61. كلمات الصوفية p. 165.

62. رسالة في بيان المعجزات والكرامات والأعاجب.

63. For example, النكت والفوائد في العلم الطبيعة 167; رسالة في العقول p. 418; رسالة الزيارة والدعاء p. 284.

64. رسالة في ماهية العشق p. 26; تعليقات p. 100.

65. أحوال النفس ch. 3.

66. مبحث عن القوى النفسانية ch. 10; cf. النكت والفوائد في العلم الطبيعة 163-165; الرسالة في السعادة p. 13; تعليقات p. 23.

67. الشفاء pp. 212-220; cf. النكت والفوائد في العلم الطبيعة pp. 167, 172.

68. رسالة في الحدود pp. 68-70; رسالة في العقول p. 416; أحوال النفس pp. 21; عيون المسائل ,عيون الحكمة pp. 3;7-38; رسالة في إثبات النبوة pp. 43-44.

69. P. 416.

70. P. 44.

71. Ibid., pp. 167-168; تعليقات p. 83; الرؤية والتعبير pp. 283-288, 290-294.

72. أحوال النفس ch. 7; عيون الحكمة pp. 35, 38; الرسالة الأحضوية في المعاد pp. 167, 175; رسالة في السعادة p. 12.

73. P. 8.

74. أحوال النفس ch. 4 & 9; مبحث عن القوى النفسانية ch. 9; عيون المسائل 21; cfr. رسالة في السعادة p. 15; رسالة في الموت p. 379; الإشارات، نمط 3, f.1, 1-4; الرسالة الأحضوية في المعاد pp. 153-183, 213.

75. الإشارات n. 3, f. l, 1-4; الشفاء m. 1, f. l, 1; a similar argument is found in مسائل عن أحوال الروح.

76. Cf. رسالة إلى أبي عبد أجوزجاني... في أمر النفس النكت والفوائد في العلم الطبيعة p. 177-178; كلمات الصوبية p. 166; الرسالة الأضحوية في المعاد 185-189; تعليقات pp. 63-64, 110; Ta`līqāt, p. 81.

77. تعليقات ch. 8, & pp. 65, 107, 145; النكت والفوائد في العلم الطبيعة p. 177-178; كلمات الصوفية 159, 178; الرسالة الأضحوية في المعاد 125-133; الشفاء: النفس m. 5, f. 3; كلمات الصوفية p. 178.

78. أحوال النفس ch. 10; الشفاء: النفس m. 5, f. 4; كلمات الصوفية pp. 135, 139, 135, 167, 207; الرسالة الأضحوية في المعاد 99-139; تعليقات pp. 65, 67.

79. P. 14.

80. P. 159.

81. P. 189; cf. رسالة في الحدود p. 91.

82. Pp. 29-31, 67-97, 107, 205.

83. This criticism of the Sūfīs, taken up by Ibn-Rushd, is a frequent theme in Ibn-Bājja; see رسالة الوداع pp. 121 ff. where he criticizes the منقذ of al-Ghazālī, and اتصال العقل بالإنسان pp. 166-167, 171.

84. اتصال العقل بالإنسان pp. 160-161.

85. اتصال العقل بالإنسان pp. 130-131.

86. Pp. 178-180.

87. P. 215.

88. P. 124.

89. P. 1489.

90. (جوامع) كتاب النفس pp. 66-95.

91. P. 396-397; the same position appears in Tractatus de animae beatitudine et Epistola de connexione intellectus abstracti cum homine.

92. Pp. 999-412, 448-500.

93. Pp. 407, 496, 506.

94. Pp. 488 ff.

95. P. 90.

96. Pp. 121, 128.

97. P. 124.

98. P. 90.

99. تفسير ما بعد الطبيعة pp. 1489-1490.

100. تلخيص كتاب النفس p. 137.

101. Pp. 128-129; le même dans le Commentarium magnum, p. 420.

102. Pp. 130-131.

103. Cf. Contra gentiles, II, n. 69-72.

104. Ibid., II, nos. 59, 69, 73-78; De unitate intellectus contra Averroistas.

105. Contra gentiles, II, nos. 83-90.