Chapter Six: Ibn Sina
Life and Works
Ibn Sina, Avicenna (370/980-429/1037), also known as al-Ra’ is (“Master and Head”) is among the very few medieval Muslim thinkers to have written an autobiography, which was completed by his student Abu Ubayd al-Juzjani.² This autobiography was later transmitted by a number of biographers, including al-Bayhaqi (d. 565/1170), al-Qifti (d. 646/1248), Ibn Abi Usaybiah (d. 669/1270) and Ibn Khallikan (d.680/1282).
Ibn Sina was born in Afshanah (a small village neighbouring Bukhara, the capital of the Samanid dynasty), where his farther ‘Abd Allah, originally from Balkh, met and married Sitarah. They had three sons, ‘Ali, al-Husayn (Ibn Sina) and Mahmud. When Ibn Sina was about five years of age, the family moved to Bukhara. There the farther was appointed governor of Kharmayathnah, a village in the suburbs of Bukhara.
The rest of the story of Ibn Sina’s life, education and career is well known, and there is no need to recount it here in detail. Suffice it to say that the most striking features of this story, as he and al-Juzjani tell it, are (1) his completing the study of the Qur’an and Islamic literature by the age of ten and the rest of the sciences, including Islamic law, astronomy, medicine, logic and philosophy, by the age of eighteen, and (2) his enormous productivity in spite of the unstable political conditions under which he lived that forced him at times to flee from one territory to another, to move in disguise and even to be imprisoned. His great achievement in the various branches of learning seems to have resulted from a rare memory that enabled him to retain by heart, for example, the Qur’an and Aristotle’s Metaphysics; a high intellectual curiosity that helped him consider and solve difficult problems even in his sleep; and an inner determination that generated extraordinary physical and intellectual energy. The number of works he wrote (estimated to be between 100 and 250), the quality of his work and his involvement in medical practice, teaching and politics all reveal an unusual level of competence.
At a very early age, Ibn Sina was introduced to various religious, philosophical and scientific teachings. For example, he was introduced to the Epistles of the Brethren of Purity and Isma’ilism by his father, who was a member of this sect. He was also exposed to the Sunni doctrine, as his fiqh teacher Ismail al-Zahid, was a Sunni, and to Twelve-
Imam Shi’ism. In addition, he was given some background in logic, geometry and astronomy by his other teacher, al-Natili. He exercised his independence of though very quickly, however. First, he dispensed with reaches, continuing his education on his own; and second, he did not adhere to any of the doctrines to which he was exposed.
Rather, he drew on various sources, selecting only what he considered convincing. Thus, we see in his system traces of Platonism, Aristotelians tendency, is not purely Aristotelian, as it is usually considered. The theory of creation, for example, which is basically Neo-Platonism, and that of prophecy, which is Islamic in essence, they are but two examples of its many non-Aristotelian teachings. Al-Juzjani confirms the uniqueness of this work and asserts that it is nothing but the product of Ibn Sina’s own thought.6 Ibn SIna himself makes a similar point, stressing his originality in this work, especially, in the Logic and Physics.7
The most important of Ibn Sina’s books are al-Qanun fi’l-tibb (“The Canon of Medicine”), al-shifa’ (“Healing”), al-Najah (“Deliverance”), ‘Uyun al-hikmah (“Sources of Wisdom”), Danishmama-yi- ‘ala’i (“the book of Science Dedicated to ‘Ala’ al-Dawlah”) and al-Isharat wa’l-tanbihat (“Remarks and Admonitions”). Al-Qanun fi’ltibb consists of five parts. Translated into Latin a number of times, it was considered the most important medical source both in the East and in the West for about five centuries (i.e., until the beginning of the eleventh/seventh century) and continues to be the primary source of Islamic medicine wherever it is practiced to this day, such as the Indo-Pakistani subcontinent. The enormous amount of material in al-Shifa’, which is the most detailed philosophical work of Ibn Sina, is grouped under four main topics: Logic, Physic into eight, and Mathematics into four. Physics (with the exception of the two parts dealing with animals and plants, which were completed after Mathematics) was the first to be written, followed by Metaphysics, then Logic, and finally Mathematics. Al-Najah, which is a summary of al-Shifa’, also consists of four parts. The Logic, physics and Metaphysics of this work were prepared by Ibn Sina and the Mathematics by al-Juzjani. ‘Uyun al-hikmah, known also as al-Mujaz (“Epitome”). Seems to have been intended for class instruction in Logic, physics and metaphysics. This is evident from the simplicity, clarity and drevity with which the work is presented. Danishmama-yi ‘alai also consists of four parts and is particularly significant in that it is the first work of Islamic Peripatetic philosophy in the Persian language. Al-Isharat wa’l-tanbihat, which is the most mature and most comprehensive philosophical work of Ibn Sina, also consists of Logic, Physics and Metaphysics. It closes with a treatment of mysticism, a treatment in its Sufi sense than metaphysics. In addition, Ibn SIna left a number of essays and poems. Some of his most important essays are Hayy ibn Yaqzan (“The Living Son of the Vigilant”), Risalat al-tayr (“the Epistle of the Bird”). His most important poems are al-Urjuzah fi’l-tibb (an iambic poem on medicine),8 al-Qasidat al-muzdawijah (anode in couples)9, and al-Qasidat al-‘dat al-ayniyyah (an ode whose verses end with the letter’).10 He also wrote a number of Persian Poems.
Division of sciences
Ibn SIna understands “the purpose of philosophy to be the determination of the realities of all things, inasmuch as that is possible for a human being”. There are two types of philosophy, theoretical and practical. The former seeks knowledge of the truth; the latter of the good. 12 The purpose of theoretical philosophy is to perfect the soul through knowledge alone.
The purpose of practical philosophy is knowledge of what must be done; so that the soul acts in accordance with this knowledge 13 Theoretical philosophy is knowledge of things that exist not owing to our choice and action. Practical philosophy is knowledge of things that exist on account of our choice and action.
The individual subjects of theoretical knowledge are of two main types: those to which movement can be attached, such as humanity, queerness and unity and those to which movement cannot be attached, such as God and the intellect. The former are again divided into those that cannot exist unless movement is attached to them, such as humanity and sugariness; and those that can exist without any movement being attached to them, such as unity and multiplicity. The former of the last two types is either such that it cannot be free movement either in reality or in though (e.g., humanity and horsiness), or such that it can be fore from movement in thought but not in reality (e.g., sugariness). 14
There are, therefore three branches of theoretical philosophy: that which deals with things inasmuch as movement is attached to them both in reality and in thought; that which deals with things inasmuch as movement is attached to them in reality but not in thought; and that which deals with things inasmuch as movement is attached to them neither in reality nor in though, regardless of whether movement can be attached to them, as in the case of unity, or cannot be attached to them, as in the case of God. The first is physics, the second is pure mathematics and the third is metaphysics. 15
Practical philosophy, on the other hand, is concerned with learning one of the following: (1) the principles on which pubic sharing among people is based, (2) the principles on which personal sharing among peoples is based, or (3) the principles on which the affairs of the individual are based. The first is the management; 16 and the third is management of the individual, referred to as ethics.17The principles of practical philosophy are derived from the divine shari ah, and its complete definitions are made clear by the divine Shari’ah.18
The benefit of the science of management of the city is to make known the manner in which sharing among people accurse for the purpose of the well-being of the human body and of the preservation of humanity.
The benefit of the science of home management is to make known the type of sharing that must take place among the members of the same home in order to ensure their well-being. Such sharing occurs between husband and wife, and child, and master and slave. The science of management of the individual yields a twofold benefit-tomakeknown the virtues and the manner of acquiring them in order to refine the soul, and to make known the vices and the manner of avoiding them in order to purify the soul.19
Only an outline of the most important aspects of Ibn SIna’s philosophy can be provided here. The most essential elements of this logic, which he considers the introductory part to philosophy, 20 are discussed in Chapter 48 below. Only a sketch of his general logical scheme will be given in this chapter.
Logic
Ibn Sina considers logic as the key to philosophy, whose pursuit (knowledge) is the key to human happiness. Logic performs this function by helping to derive unknown concepts and judgments from known ones, thus increasing our degree of knowledge (concepts are mental objects with no affirmation or negation; judgments are mental objects with affirmation or negation). Logic does this by acting as a set of rules for distinguishing the valid from the invalid explanatory phrases, which embody concepts and are the instruments for moving from known concepts to unknown ones, and proofs, which embody judgment and are the instruments for moving from known judgments to unknown ones. Since the valid leads to certitude and the invalid to falsehood, knowledge is attained only through the use of logic, except when, on rare occasions, God provides this knowledge without any human effort. 21
While the logician’s function is to open the way for the knowledge of the natures of things, he or she is not concerned with such natures in themselves or as they exist externally or in the mind but only with concepts, representing these natures under the aspect of being subject or predicate, individual or universal, essential or particular. 22 Only when the concepts, of the natures of things are considered inasmuch as they have certain states and a certain relationship to each other can they help to move though from the known to the unknown. Even though the primary concern of the logician is concepts inasmuch as they are arranged in a certain manner, the logician must deal with expressions, as arranged in a certain manner; the logician must deal with expressions, as they are the only way to reason about or to communicate concepts. 23 With this in mind, Ibn Sina opens his logical treatises with discussions, of expressions, beginning with single expressions, the smallest elements of the explanatory phrase and proof.
As the ultimate goal of the logician is to pave the way for knowledge of the natures of things, universal expressions that mirror universal concepts, which in turn mirror these natures, must be his or her concern.
That is why most of the discussion of the single expression focuses on the study of universal terms (the five periodical): genus, species, difference, property and common accident. The main types of the explanatory phrase, of a genus and a differences, is said to be the most reliable form of the explanatory phrase.
The proof, which utilizes explanatory phrase as its parts these are the propositions or premises - is of three types: syllogism, induction and analogy. The conjunctive, the conditional and the exceptive. The propositions that form the premises of the various types of the syllogism fall into nine categories. Each of these categories derives its assent or judgment from a different source, which will be indicated here in parentheses following the name of the category of propositions: sensible (from the external senses only); experiential or observational (from memory of repeated sense experience); based on unanimous traditions (from multiple testimonies); received (from scholars or respected religious leaders); estimative (from the estimative power); widespread (from being widely known); presumed (from the realization that the opposite is possible); imagined (from resemblance to propositions involving assent); primary (from the clarity of reason). 24
Demonstrations is the most reliable form of the syllogism composed of propositions characterized by certainty, it leads to a conclusion with certainty. Such propositions are primary, experiential, sensible or widely known. A demonstration requires three elements: those principles with which the demonstration is made (the premises), those issues that are the object of demonstration (the problems), and those subjects in which demonstration is made.
Ibn Sina usually closes his logical discussions with a study of ambiguities, whether in expression or in meaning.
Physics
Physic is concerned with the study of certain principles and of the things that are attached to natural bodies. These intellect is considered a natural principle inasmuch as it is the cause of holding matter and form together and, as such, is the relation to the physics realm is the agent intellect discussed in physics, and not inasmuch as it has such and such a nature or such and such a relation to separate principles or intelligible. The things that are attached to natural bodies include motion, rest, time, place, void, the finite and so forth.
For example, every natural body is said to have a natural place and a natural shape. All natural motions lead to a creative, circular motion belongs to the heavenly bodies, which are followed by the bodies that are subject to generation and corruption. This first of the latter type of bodies in existence is the four elements: water, air, fire and earth. These elements are subject to the celestial influences. 26 When the four elements come together, their mixtures vary in temperament owing to the influence of the celestial powers. This variation in temperament results in the composition of these elements: minerals, plants and animals (the last and highest of whom are human beings). The closer their temperament is to equilibrium, the higher the form of the natural body. For this reason, there is a gradation in being from minerals to plants to animals, as well as a gradation of the various kinds subsumed under every level of these three types of being. The closest temperament to equilibrium causes the existence of human bodies, which have the highest form in the terrestrial sphere -this form being the human soul. This kind of soul is defined as “a primary perfection of an organic, natural body to which it belongs to perform acts of life”. 27Primary perfection is what gives actuality to the species of a thing, as shape gives actuality to the sword. This is to be contrasted with secondary perfection, which is what gives actuality to the actions and reactions that follow upon the species, as does cutting for the sword. 28 The discussion of the soul takes up a large portion of Ibn Sina’s Physic. We are told that if the function of the soul is limited to nutrition, growth and reproduction, it is a mere plant soul. 29 If sensation and movement are added to these, then it is a mere animal soul. 30 The soul of a human being includes these, but has a practical and the theoretical faculties or intellects. 31 When this rational part occurs to a being, that being becomes a human being. 32 Through conjunction with the agent intellect that contains the intelligible, the theoretical part of the rational soul receives its proper perfection, the perfection that makes it what it is. This perfection is the best thing a human being can achieve; at it is the best thing for any being to achieve is proper perfection, which completes its nature.
A brief discussion of the animal and rational souls is now in order, given the important role that they play in achieving this perfection. As mentioned, the animal soul has sensation and movement. The sensitive part consists of the external and the internal senses. The external senses are, in order of necessity for animals, touch, taste, smell, hearing and sight. The internal ones are common sense, representational faculty, imagination, estimative faculty and memory. The common sense is the faculty in which external sensations or forms of external objects collect. It is the faculty that enables us to judge, for example, the honey is sweet when we perceive honey visually, without the gustatory sensation that it is sweet. The reason is that the faculty of common sense simultaneously receives from the different external senses the different sensations of the one external object, which we call honey. This makes it possible for us to distinguish between the yellow colour and the sweet taste of honey, while realizing at the same time that they belong to the same object. The representational faculty retains the forms that the common sense receives from the outside. The objects In contrast, the objects of the common sense are present only when the external objects are there - except in rare cases when they are poured into the common sense from the internal senses, which either manufacture them or receive them from the divine world. 33 The estimative faculty is said to grasp sense notions that are different from the sense forms grasped by the common sense. These notions are exemplified by the lamb’s fear of the wolf. The memory retains the notions of the estimative faculty, as the representational faculty retains the sense forms. Finally, the imagination combines some objects of the representational faculty and of memory with each other, while separating the rest from each other. It must be mentioned that this faculty is called imagination, but only if employed by the estimative faculty. If it is employed by the intellect, it is called cognition. 34The locomotive part of the soul is responsible for the motion of the organs by means of the nerves and muscles due to the will. This motion is assisted by primary and secondary instruments. The primary ones, which concern us here, are either the imagination or the rational soul. These cause inclination either in the direction of or away from a perceived object. Inclination in the direction of an object is for an object that is imagined or presumed to be useful.
When a power expresses such an inclination, it is called appetitive, which the inclination itself is called a petition.
Inclination away from an object is for an object that is imagined or presumed harmful. When a power expresses such an inclinations. It is called irascible, while the inclination itself is called anger. Both intellection and motion are affected by the condition of their instruments. If, for example, the instrument of sight is diseased or has aged, then sight declines or disintegrates totally. 35 The human or rational soul performs either bodily actions and reactions, or purely intellective actions. The former do not belong to it and proceed from it and the body, whereas the latter belong to it and proceed from its essence.
The actions that the rational soul performs in conjunction with the body are exemplified by consideration of the particular matters that must be done or avoided voluntarily, including the practical crafts such as carpentry, farming and animal husbandry. Reactions, on the other hand, are states consequent upon the preparations of the body and the rational soul, such as the preparation for crying or shyness. The purely intellective acts, which are performed by the rational soul, consist of grasping the quiddities or natures of things as universal concepts, such as “humanity” and “horsiness”. Such concepts cannot be grasped by any of the external or internal powers, for these powers belong to the animal world and thus whatever they grasp must be to some degree material and particular. 36 Contrary to the animal powers, the rational soul can grasp the quiddities or natures of things apart from matter and particularity. From such universal concepts, it composes judgments possessing certainty.
As mentioned, the rational soul has two parts, one with a capacity for action and the other with a capacity for action and the other with a capacity for knowledge. The former, called the practical intellect, is directed towards the body. With it, one can distinguish between what must and what must not be done, as well as between good and bad particular things. This intellect is perfected through habits and experiences. The latter, called the theoretical intellect, is directed towards the divine world and enables one to receive the intelligible. 37
The theoretical intellect passes through four stages. Firstly, it is in potentiality and has not yet formed any concepts or grasped any intelligible. This is the potential or material (al-aql al-hayulani). This intellect is called material, not because it is material in nature but because it has the capacity for receiving intelligible forms as matter has the capacity for receiving material forms.
Secondly, it is this potentiality actualized by the occurring of primary intelligibles in it.
This is the habitual intellect (al-aql bi’lmalakah).
Thirdly, it is the acquisition of the intelligibles made constant. This is the actual intellect (al-aql bi’l-fi’l). Fourthly, it is these intelligibles themselves. This is the acquired intellect (al-aql al-mustafad). 38
For a thing to move from potentiality to actuality, another thing, which is already in actuality, must give it the form that actualizes it. What body, because it must already possess the intelligible forms, which are non-material and which it gives to our theoretical intellect. Therefore it must be an intellect-this intellect being the agent intellect. The agent intellect sheds its light on the objects of our imagination, which have been received originally from the external world, thus making them visible to our theoretical intellect, as the sun sheds its light on the external things, thus making them visible to our sight. When the light of the agent intellect reaches the objects of the imagination, it renders them intelligible to our theoretical intellect by abstracting them from matter. 39
Since the rational soul can receive the intelligible forms, it must be in its substance of the nature of these forms. If what receives the intelligible forms were a body or a power in a body, these forms would be divisible, and a simple form could not be intelligible. Arguments are advanced to show that the idea that the rational soul is immaterial. 40 It follows that the rational soul is simple, for multiplicity lies in materiality. Because it is simple, it is indestructible. Contrary to Alexander of Aphrodisias and al-Farabi, who believe that the only human soul assured of indestructibility is that which knows at least some realities -that which is completely deficient in such knowledge is eventually destroyed-Ibn SIna considers all human or rational souls to be indestructible? To him, knowledge of the realities of things is necessary only for happiness but not for existence after death.
Metaphysics
Metaphysics 41is the science that provides knowledge of the principles of theoretical philosophy. This it does by demonstrating through the intellect the complete acquisition of these principles.42 Metaphysics deals with the existent inasmuch as it exists, that is, with the general or absolute existent and what is attached to it. In other words, the subject of metaphysics is the existent, not inasmuch as it applies to some things and inasmuch as something particular is attached to it, as in physics and mathematics (such as quantity and quality, action and reaction, which are attached to the objects of physics) but inasmuch as it applies to the principle of existence and inasmuch as something universal is attached to it (such as unity and multicity, potentiality and actuality, eternity and coming into being, cause and effect, universality and particularity, completeness and incompleteness, necessity and possibility). 43 These qualities are essential accidents of the particular existent. We understand from Ibn Sina’s logic that an essential accident is one that does not constitute or enter into the essence of a thing, yet necessarily accompanies it, as “laughter” for “human being”. A nonessential accident neither constitutes the essence of a thing nor necessarily accompanies it; however, it resides in it, as “white” may reside in “human being”.
The existent is either substance or accident. A substance is anything that is not in a subject, whether or not it is in matter. Thus substance is of two main types: (1) that which is in matter, and (2) that which is not in matter. The latter category is broken down into three types (2a) matter, (2b) that which is accompanied by matter, and (2c) that which is neither matter nor accompanied by matter. This scheme means that substance is of four types: (1) form in matter, as the soul is in the body (2a) matter with no form-this is absolute matter, which has no existence in actuality but only in conception; (2b) the composite of form and matter, as the human being is a composite of soul and body, (2c) form separate from matter, as God or any intellect is neither matter nor in contact with matter. 44Accident on the other hand, is in a subject and is divided into nine types: quality, quantity, relation, time, place, position, condition, action and reaction.
The existence of a thing is either necessary or possible (contingent). Necessary existence is such that if the thing to which it belongs is assumed to be non-existent, impossibility arises. Possible existence is such that if the thing to which it belongs is assumed to be non-existent or existent, no impossibility arises. 45Ibn Sina mentions that in other contexts “possible, existence” could also be used in the sense of “being in potentiality”. 46Necessary existencesare either that which always belongs to a thing through that thing itself, or that which always belongs to it through another. For example, the existence of burning is necessary, not because of the burning itself, but because of the meeting of two things, one naturally capable of burning and the other naturally capable of being burnt. 57 What is necessary through itself cannot be necessary through another and conversely. For example, if the existence of A is necessary through A, itself, this existence cannot be necessary through B.
Similarly, if it is necessary through B, it cannot be necessary through A, itself. This is to say that if, is the second case, one considers A in itself, one finds its existence non-necessary, or possible in itself. If this is not the case, its existence would be either necessary in itself, but this has been denied, or impossible without another. Its existence through another is other than its existence without another. By the former, it is necessary; by the latter, it is possible. 48
The existence of a being necessary in itself is determined on the basis of two principles: first, the chain of possible beings at any time cannot be infinite, thus, it must lead to a necessary cause external to this chain - this cause being the Necessary Existent or Being, otherwise known as God.
Being eternally prior in existence to everything and the source of the existence of everything, this Existent is said to be the first cause. 50 It is free from matter, one and simple in all respects. 51 Thus it has no genus or difference, the two necessary elements of a definition. Therefore there is no definition of it, but only a name. Being immaterial, it is purely good, for only in matter, the source of privation, does evil lie.52 Owing to its immateriality, it is also an intellect, and, owing to its simplicity, the intellect and the intelligible in it are one.53 In itself, it is the Beloved and the Lover, the pleasurable and the pleased. It is the Beloved because it is the highest Beauty. It is the highest beauty because there is no highest beauty than that of being a pure intellect, above all manner of deficiency, and one in all respects. Suitable and apprehended beauty or goodness is desired and beloved. The more the apprehended is beautiful, the more the power of apprehension loves it and finds pleasure in it. 54
Thus the Necessary Being, who is most beautiful, perfect, and best, who apprehends itself at this ultimate beauty and goodness and in the most complete manner of apprehension, and who apprehends the apprehender and the apprehended as one in reality is in essence, and by its essence, the greatest lover and beloved and the greatest thing pleased and pleasurable.
From this Necessary Being the rest of the existing things overflow through the process of emanation. The first things that emanate are the celestial intellects, followed by the celestial souls, the celestial bodies and finally terrestrial beings. All these things emanate from it in eternity; otherwise, a state would arise in it that was not there before. But this is impossible in a being whose existence is necessary in all respects. 56 This emanation is a necessary outcome of God’s Essence and cannot be linked to any intention external to His Essence. Firstly, there is nothing in Him external to His Essence-He is a total simplicity, but He can be considered from different points of view. It is only by virtue of such consideration that one can speak of His Attributes. Secondly, even if it were possible for Him to have among such Attributes any intention relating to the world. “The reason is that every intended.
This is because if a thing is for the sake of another, that other is more complete in existence than it.” 57 This is to say that whatever is more complete in existence then another cannot intend that other.
God, therefore, cannot intend the world or anything in the world, since He is more complete in existence than the world.
Even though neither God nor any other cause can be perfected essentially by its effects and therefore cannot intend its effects or anything for them, still it may lead accidentally to beneficial effects and, if it is divine, know and be pleased with these effects. Health, for example, is such “in substance and essence, not to benefit the sick; but it results in benefiting the sick”.
58Similar to health, superior causes are what they are in themselves, not to benefit anything else; but they do benefit other things accidentally. They differ from health, though, in that they know the things that exist. 59Still, providence is attributed to God, the first cause of all things. Providence must be understood, however, not in the sense of divine guidance of the world or concern about it. Rather, providence is defined as God’s knowledge of the order of existence and the emanation of this order inasmuch as that is possible, and His being pleased with it. 60
Ibn Sina’s thought had a clear and strong impact on the East and on the West, in science, literature and philosophy. The impact of his philosophical thought, which concerns us here, was exhibited in a large number of commentaries on his works and in other forms of writings it. The best known of such commentaries are thoseof Ibn Kammunah, Fakhr al-Din al-Razi and Nasir al-Din al-Tusi on al-Isharat, and Sadr al-Din al-Shirazi on part of al-Shifa’. Among the most prominent Eastern thinkers whose thought reflects that of Ibn Sina are al-Tusi, Suhrawardi, Qutb al-Din al-Shiraz, Mir Damad, Sadr al-Din al-Shirazi (Mulla Sadra) and the Syriac Christian Ibn al-Ibri.
Suhrawardi’s and al-Shirazi’s theories of illumination, for example, stem from Ibn Sina’s “Oriental philosophy”. Also, their discussions of being and essence were generated by Ibn Sina’s view on this subject.
Ibn al-Ibri too adheres closely to Ibn Sina’s analysis of God’s relationship to the world, the presence of evil, and the nature and unity of the human soul as well as the impossibility of the soul’s pre-existence and transmigration. 61
But, as mentioned, not all those who felt the effect of Ibn Sina’s thought responded to it positively. Ibn Sina had his strong critics, such as al-Ghazzali and al-
Shahrastani in the East, and William of Auvergne and Thomas Aquinas in the West.
These critics rejected primarily his ideas concerning God’s nature, knowledge of particulars and relationship to the world, as well as the eternity of the universe and the denial of the resurrection of the body. Also, Ibn Rushd, who in his major work, The Incoherence of Incoherence, seeks to defend philosophy as embodied primarily in Ibn Sina’s works, charges that Ibn Sina misunderstood and distorted Aristotle at times.
Such opposition to Ibn Sina’s ideas, however, did not prevent even these critics from borrowing heavily from him. Al-
Ghazzali’s logic and philosophical terminology, to give but two examples, are, for the most part, those of Ibn Sina. Also, the distinction Ibn Sina introduced in his theodicy, for example, between evil in itself and evil for another was borrowed by Aquinas and from him by Suarez. Because Ibn Sina’s works are not sufficiently know in the West, however, the credit for this distinction is given in the West to Aquinas.
Furthermore, two of Aquinas’s well-known proofs of God’s existence, that from efficiency and that from contingency, as well as his distinction between essence and existence, were also borrowed from Ibn Sina. The numerous references Aquinas gives to Ibn Sina in Being and Essence and elsewhere is sufficient to show the influence Ibn Sina had on his prominent Christian philosopher and theologian whose ideas dominated Western thought for so long. Gundissalinus, Albert the Great and Roger Bacon are also among the Western thinkers whose work reflected elements of Ibn Sina’s thought, especially with regard to the nature of the human soul. No doubt the following factors facilitated Ibn Sina’s influence on Latin philosophical circles; first, the translation parts of al-shifa’s as early as the twelfth and thirteenth Christian centuries; and, second, Ibn Sina’s efforts to synthesize Greek and Islamic though, an attempt in which the West found the seed for a synthesis between Greek Philosophy and Christianity.