In the year 529, Justinian closed the Schools of Athens, but fortunately for the West, Greek learning had been transmitted to the Near East, principally through the institutions of Alexandria and the Christian communities of Syria and Persia. Later, after the advent of Islam, this learning was fostered and developed by various Islamic philosophers and eventually carried across North Africa into Spain, where it flourished in such places as Toledo and Cordova. From the eleventh to the thirteenth centuries, it trickled and then flooded into Western Europe to augment the Christians’ meager and unbalanced knowledge of Greek philosophy.

Avicenna was, perhaps, the most important Islamic philosopher. Besides being a prolific writer on philosophy and religion, he was a court scholar and physician, an active politician, a civil administrator, and the writer of medical texts that were standard works in Europe through the seventeenth century. Of his approximately one hundred works, the two most important are the philosophic encyclopedia, Kitab al-Shifa’ (early eleventh century; book of healing), the bulk of which was known to late medieval thinkers, and an abridgment of it, Kitab al-Najat, commonly known as The Book of Deliverance. This essay is based primarily on the section of the work dealing with Avicenna’s philosophy of mind, which was translated by F. Rahman and published under the title Avicenna’s Psychology.


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God and the Intelligences

The First Intelligence can also create by contemplation, but because it is a finite intelligence, it can contemplate and create in different ways. In contemplating God, it creates the Second Intelligence. In contemplating its own essence and in knowing that it is a contingent being characterized by potentiality, it creates the body of the first celestial sphere. In contemplating itself and in knowing its existence as necessary in that it flows necessarily from God, it generates the soul of the first celestial sphere.

Because the celestial sphere is attached to a body, its soul is not a pure intelligence and therefore does not create, but it does seek to emulate the perfection of its creator, the First Intelligence. It does so by contemplating the intelligence and by perfecting its own body. Because the only change simple celestial matter can undergo is a change of position, the soul perfects celestial matter by circular motion. Hence, the First Intelligence is the final cause of both the existence and motion of the first sphere. The Second Intelligence, by contemplating the First Intelligence and by contemplating itself in the twofold manner, produces the Third Intelligence and the body and soul of the second celestial sphere, that containing the stars. In a similar manner, further intelligences and spheres are produced as the creative process works down through the spheres of Saturn, Jupiter, Mars, the Sun, Venus, Mercury, and the Moon. The Tenth Intelligence does not produce a...

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The External and Internal Senses

Avicenna’s reliance on Aristotle, and in particular on Aristotle’s De anima (second Athenian period, 335-323 b.c.e.; On the Soul, 1812) is evidenced from the beginning of his psychology when he classifies souls as vegetable, animal, and human. The vegetable soul is characterized by the faculties of growth, reproduction, and nutrition; the animal has, in addition, those of motion and perception; and the human being is completed by the faculty of reason. There are really two faculties of motion in the animal soul: a psychic one characterized by desire and anger, which incite motion toward objects or away from them, and a physical one that actually moves the body by contracting and relaxing the muscles. There are five external senses, each operative when the form of the sensed object is impressed on the physical sense organ. For instance, when light falls on an object, it transmits an image through the transparent medium, and this image is impressed on the vitreous humor of the eye where it is apprehended by the psychic faculty of sight.

Avicenna’s analysis of the internal sense goes considerably beyond that of Aristotle, who did not distinguish explicitly between internal and external senses, and it anticipates in considerable detail that of the Scholastics. There are five internal senses: fantasy or common sense, representation, imagination, the estimative sense, and the recollective or retentive sense. These are unique faculties, each being associated with a different part of the brain. The common sense receives images transmitted to it by the five external senses, enabling people both to know that they differ from one another and to collate the data received from them. The function of representation or sense memory is to preserve the data received by the common sense. An external sense, such as vision, abstracts the form of a particular object from its matter, but it can do so only in the presence of the object, seeing the form with all the determinations imposed upon it by that matter and seeing it as being present in...

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Reason is divided into practical and theoretic faculties. With the help of the theoretic faculty, the practical faculty elaborates basic moral principles such as “Tyranny is wrong,” “Lying is wrong”; it considers purposes, deliberates, initiates behavior, and produces in the faculty of appetite such responses as shame and laughter.

The theoretic faculty can occur in various degrees. It may be dormant; it may develop to the point where it possesses the primary principles of thought, such as “The whole is greater than its part” and “Things equal to a third are equal to one another”; or it may perfect its potentiality by grasping the secondary principles as well and thus be in a position to think without the further acquisition of any other principles. These are the various degrees of the Potential Intellect. Finally, the intellect may actually think, exercising the capacities it has perfected at the prior stage. It is then called the Actual or Acquired Intellect. This last stage is not attained unless the Potential Intellect is activated by the Agent Intellect, the Tenth Intelligence.

In order to achieve its end of contemplating pure forms, theoretic reason must complete the process of abstracting forms from matter, a process already initiated by the external and internal senses. That is, it must turn to the imagination, to the images of particular objects, and, through the agency of the Agent Intellect, grasp the forms appearing...

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Immateriality and the Soul

Knowledge involves the discovery of necessary relations between universals, relations noted directly by intuition, which is a kind of illumination, or established indirectly by syllogistic reasoning. Although his model seems to be that of a body of knowledge derived by reason alone from universals and self-evident truths, Avicenna does point out that much knowledge about the world, though certain, is based partly on experience. Having noted the constant conjunction between things such as humankind and rationality and day and being light, and constant disjunction such as its not being both day and night, one must conclude that the noted constancy reveals a necessary conjunction or disjunction. Thus one must acknowledge necessary truths about the world, truths such as “Humankind is rational,” “If it is day, then it is light,” and “Either it is day or it is night.” However, apart from this sort of assistance and the assistance of the internal senses as providers of data, the intellect does not need the assistance of the body. It does not operate through a physical organ, for it can know itself and is not disrupted by strong stimuli, as the physical organ of sight is disrupted by a dazzling light. Furthermore, as is required by a faculty that apprehends pure forms, it is an immaterial faculty.

In defending his view that the soul is an immaterial substance, Avicenna invokes his famous “man in the void” argument. Suppose, he says, that a man is...

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The Active Intellect and the Human Intellect

To complete the survey of Avicenna’s psychology, one must consider the relationship between the human intellect and the Active Intellect. The human intellect does not achieve its highest status, that of apprehending universals and the relations between them, unless it is activated by the Tenth Intelligence, which is the Active Intellect, or Giver of Forms. Avicenna describes the Active Intellect as radiating a power that illuminates the potentially intelligible but actually sensible forms of imagination, thereby making them intelligible and present to a suitably prepared mind. In this way, Potential Intellect becomes an Actual or Acquired Intellect. In this process, images are important for two reasons: first, one must abstract...

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Additional Reading

Afnan, Soheil M. Avicenna: His Life and Works. London: George Allen and Unwin, 1958. The author stresses the impact of Avicenna’s philosophy upon the thinkers of the Arabic-speaking world.

Arberry, Arthur J. Avicenna on Theology. London: John Murray, 1951. This important brief work contains Avicenna’s own autobiography and its continuation by his disciple and companion, Abu ‘Ubaid al-Juzjani, as well as Arberry’s discussion of Avicenna’s defense of monotheism and the immortality of the soul.

Avicenna. The Life of Ibn Sina: A Critical Edition....

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