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Ibn Rushd’s Defense of Philosophy

as a Response to Ghazālī’s Challenge in
the Name of Islamic Theology


Catherine Perry

Source: Studies in Comparative Religion, Vol. 17, No. 1 & 2 (Winter-Spring, 1985). © World Wisdom, Inc.

In eleventh century Persia, Abū Hamīd al-Ghazālī, an Islamic jurist and theologian who had at one time professed a deep interest in philosophy, set about attacking the Greek-inspired philosophers, particularly Ibn Sīnā and al-Fārābī, some of whose tenets he judged to be contrary to the teachings contained in the Koranic Revelation and thus to have a pernicious influence on Islamic thought and faith. In his book Tahāfut al-Falāsifah (“The Incoherence of the Philosophers”), written in 1095,[1] he attempted—as the title suggests—to refute what he considered to be the errors of these philosophers, using their own demonstrative methods and argumentation. Because of his profound learning and his knowledge of the art of argumentation, his work had such a profound impact on the world of his time that the philosophical tradition of Eastern Islam underwent a severe decline and eventually died.

Philosophy continued in the West, however; and some eighty years later, Abū-l-Walīd Ibn Rushd,[2] a Peripatetic philosopher, who also combined the functions of judge in Cordova and of personal physician to the Almohad sovereigns, responded to Ghazālī’s attacks in a book entitled Tahāfut al-Tahāfut (“The Incoherence of the Incoherence”), where he alternately cited Ghazālī’s views and his own. Ibn Rushd’s reply was the ultimate endeavor of this philosophical system to reassert itself in the midst of growing opposition and to prove its legitimacy within the Islamic religion; for at that time philosophers were under the accusation of heresy, an accusation which threatened them with the penalty of death. Ibn Rushd himself went through a period of disgrace, and many of his original works were publicly burned. With him, the great philosophical tradition which had come to full bloom in the eleventh and twelfth centuries is generally considered to have reached its end.[3] Nonetheless, it left a legacy which was absorbed and molded by the science of Kalām—the predominant school of thought from then on, and by some of the most eminent Sūfis, such as Ibn ‘Arabī.

As an illustration of Ghazālī’s contention against philosophy, it will be interesting to look at certain of the specific arguments to which Ibn Rushd replied. A comparison of their respective claims may well show that each is right in his own domain and that their disagreements are not so great as might appear at first sight. Firstly, however, let us place philosophy in general and Ibn Rushd in particular within the context of the Islamic tradition.

In its highest reaches, Islamic philosophy deals with the dimension of al-Haqīqah, or essential truth, and thus the source of all other truth. Taking certainty for their point of departure, the philosophers aim to achieve through reasoning a greater understanding of God, the Revelation, and the nature of the universe. Their intention is not to create doubt and confusion but to acquire mental enlightenment through discovery of the truth; and, ideally, philosophy becomes the wisdom of the sages in the sense that it is as much practical as theoretical knowledge, involving the totality of man and not only his rational faculty:

Philosophy is the knowledge of the reality of things within man’s possibility, because the philosopher’s end in his theoretical knowledge is to gain truth and in his practical knowledge to behave in accordance with truth.”[4]

What made it possible for philosophy to develop as a science was the Koran’s commendation of wisdom, hikmah, and the prophet’s injunctions to seek it:

“He giveth wisdom unto whom He will, and unto him to whom wisdom is given, much good hath been given.”[5]

“The acquisition of hikmah is incumbent upon thee: verily the good resides in hikmah.”[6]

However, theologians took hikmah to mean the science of Kalām, whose supremacy they wished to assert over any other form of knowledge, and this brought them into frequent conflict with the philosophers. As for Ibn Rushd, they could blame him not only for being a philosopher but also for being too rationalistic in a strict Aristotelian sense, and thus too remote from the tenets of Islamic faith, since pure rationalism seems not to rely on any power outside itself;[7] this was perceived as a threat to the Muslim community since believers might eventually be induced thereby to reject revealed truth. Perhaps Ibn Rushd was overly given to reason; but in all fairness, it should be mentioned that such a judgment is no doubt largely based on his commentaries on Aristotle’s works, which are not his spontaneous teachings but rather writings produced at the bidding of the Almohad Caliph, Abū Ya‘qūb Tūsuf, who was himself fond of philosophy.

Furthermore, one of Ibn Rushd’s greatest concerns was to reconcile philosophy with religion, for he was convinced that both dealt with the same and only truth; he devoted a whole treatise, the Fasl al-Maqāl (“On the Harmony of Religion and Philosophy”), to this purpose. “Philosophy is the friend and milk-sister of religion,”[8] he says, while attempting to demonstrate the legitimacy of, and even the necessity for, philosophy as a science commanded by divine Law:

“That the Law summons to reflection on beings, and to the pursuit of knowledge about them by the intellect, is clear from several verses of the Book of God, Blessed and Exalted, such as the saying of the Exalted, ‘Reflect, ye who have vision’: this is textual authority for the obligation to use intellectual reasoning.”[9]

However, when the preceding Koranic phrase is examined, it is found to be cited out of context;[10] Ibn Rushd was probably unable to resist turning some verses of the Koran to the advantage of philosophy, but he was certainly neither the first nor the last to use such a stratagem in defense of his arguments. Be that as it may, such examples should not detract from the validity of his conclusion on the intrinsic worth of philosophy:

“Now since this religion is true and summons to the study which leads to knowledge of the Truth, we the Muslim community know definitely that demonstrative study does not lead to [conclusions] conflicting with what Scripture has given us; for truth does not oppose truth but accords with it and bears witness to it.”[11]

According to Ibn Rushd, however, this science is not for everyone; it must not be divulged to the common people, whose intelligence cannot apprehend the higher truths of philosophy, but should be strictly reserved to the élite, to men of learning who tread “the path of study,” seeking “to know the truth,”[12] who are “versed in profound knowledge and to whom God has permitted the sight of the true realities,”[13] and who have the “obligation to make a thorough study of the principles of religion.”[14] Moreover, no one can enter the philosophers’ circle without first receiving a sound intellectual education and acquiring a solid basis of virtue to guard against the pitfall of heresy: “One can attain knowledge only after the attainment of virtue.”[15] By introducing such measures, Ibn Rushd shows that he wants to protect the community, thereby offering reassurance to his opponents. Furthermore, he does not argue that philosophy has answers to everything, for he is well aware of the limits of reasoning, when it comes to knowledge conferred by revelation:

“We have to refer to the Law of God everything which the human mind is unable to grasp. For the knowledge which results from revelation comes only as a perfection of the sciences of the intellect; that is, any knowledge which the weakness of the human mind is, unable to grasp is bestowed upon man by God through revelation.”[16]

Finally, he deplores the fact, that instead of mutual understanding between philosophers and theologians, there should have been so much dissension, and bitter opposition to philosophy by theologians, since both are:

“companions by nature and lovers by essence and instinct…But God directs all men aright and helps everyone to love Him; He unites their hearts in the fear of Him, and removes from them hatred and loathing by His grace and His mercy!”[17]

These words can only come from a believer; there is no reason to question the sincerity of Ibn Rushd’s Islamic faith, even if some scholars have stated that in his “exoteric” treatises he is veiling his real thoughts; philosophy in a traditional world, such as that of twelfth century Cordova, was not divorced from religion in the manner of modern philosophy.[18]

*          *          *

After these preliminaries, which are essential for understanding the standpoint from which Ibn Rushd will argue against Ghazālī, let us briefly examine a problem of cause and effect, as brought up by Ghazālī in his Tahāfut al-Falāsifah. Although he intended this work to refute Ibn Sīnā and al-Fārābī, whose quasi-Platonic philosophy Ibn Rushd himself rejected in part, the argument here concerns an Aristotelian view of the world held by these two philosophers, and which Ibn Rushd also expounded.

Basing himself on the orthodox Asharite thesis in this matter, Ghazālī states that God is the sole Agent responsible for the existence of all things in the world; by “agent” he means one who is capable of acting voluntarily, and concludes that only an “act which proceeds from the will is a proper act.”[19] According to Ghazālī, not only has the world been created ex nihilo at the beginning of time, but the natural events that occur in the world at any moment are also a direct consequence of God’s continuous creative act. This view raises the critical question of how to address reason with a statement that pertains to faith; in order to be convincing, Ghazālī is obliged to explain rationally what he observes as pertaining to divine causality in the world’s phenomena.

Ghazālī has no trouble admitting that material events are connected, but he denies that there need be any causal link between them. To illustrate his assertion, he gives the example of a piece of cotton brought into contact with fire. If the cotton burns as a result of this contact it is not through any action of the fire, which is inanimate and thus incapable of voluntary action, but through God’s intervention:

“The agent of the burning is God, through His creating the black in the cotton and the disconnection of its parts, and it is God who made the cotton burn and made it ashes either through the intermediation of angels or without intermediation. For fire is a dead body which has no action, and what is the proof that it is the agent?” (pp. 316-7)

Therefore, when we talk of natural causes, it can only be figuratively, since inanimate things cannot be real agents:

“If the inanimate is called an agent, it is by metaphor, in the same way as it is spoken of metaphorically as tending and willing.” (p. 92)

If we think in terms of causes and effects with respect to a natural phenomenon such as fire, it is only through habit since we are accustomed to observing the coexistence of fire and burning. It is our experience which tells us that a piece of cotton will ignite as a consequence of its contact with fire, but in reality no natural antecedent is implied in this object’s disintegration, or in any other supposed effect:

“These things are not necessary, but…they are possible and may or may not happen, and protracted habit time after time fixes their occurrence in our minds.” (p. 324)

“Observation proves only a simultaneity, not a causation, and in reality, there is no other cause but God.” (p. 317)

Now if we acknowledge the soundness of this premise, then we can also understand that cotton might not burn when brought into contact with fire; as God determines the fate of this object through His will, He can just as well cause it not to burn as to burn:

“If it is established that the Agent creates the burning through His will when the piece of cotton is brought into contact with the fire, He can equally well omit to create it when the contact takes place.” (p. 323)

Ghazālī’s aim in raising these arguments is essentially two-fold.[20] First he wishes to confront the philosophers with their implicit denial that God is the Agent responsible for the world’s existence; according to him, “the philosophers do not regard God as endowed with will and choice,” therefore He “is not a true agent, nor is the world truly His act” (p. 95). Since for the philosophers the world is eternal, God cannot be the Agent because an act implies a beginning, and consequently the creatio ex nihilo of the theologians. It follows that the philosophers hold views that are contrary to the dogmas of Islam and should be considered heretical:

“Declare therefore openly that God has no act, so that it becomes clear that your belief is in opposition to the religion of Islam.” ( p. 96)

On the other hand, Ghazālī’s discussion of cause and effect is intended to prove that miracles are possible as a result of God’s direct intervention in the world, disrupting what one falsely assumes to be its natural order; if no natural cause is necessary, then miracles are no more miraculous than nature itself:[21]

“On its negation [natural causality] depends the possibility of affirming the existence of miracles which interrupt the usual course of nature…and those who consider the ordinary course of nature a logical necessity regard all this as impossible.” (p. 313)

As a specific example, he brings up the Koranic account of Abraham’s being supernaturally protected from harm when he was plunged into fire.[22] Here again, he accuses the philosophers of holding views contrary to Islam, since they deny the possibility that Abraham could be untouched by the fire so long as it kept its quality of burning. According to Ghazālī', since the agent of burning is God, in the case of Abraham He simply abstained from the act of burning, this act depending on His will as much as any other act.

*          *          *

As a philosopher, Ibn Rushd cannot accept the assertions of the theologian, and he replies by directing scathing attacks against Ghazālī; at the same time, he rises in defense of what he considers to be true philosophy, so as to clear it from any suspicion of heterodoxy.

Evidently and according to common sense, there are occurrences in the natural world which bring about others; nature follows physical laws which make it possible for the human mind to attain a knowledge of the world. Therefore, Ghazālī’s claim cannot be valid, because “to deny the existence of efficient causes which are observed in sensible things is sophistry.” (p. 318) Moreover, referring to the example of fire, Ibn Rushd contends that if this element’s specific function is denied, this amounts to denying the definition contained in the word “fire”; in that case, fire would lose its name and have no reality by which it could be recognized:

“If a thing had not its specific nature, it would not have a special name nor a definition…One need not therefore deny fire its burning power so long as fire keeps its name and definition.” (pp. 318-9)

According to this demonstration, Ghazālī’s denial of cause and effect results logically in the denial of his own affirmation, because if reason is not allowed to deduce causal relationships between two successive events, then it cannot operate according to its nature and so loses its power of forming valid concepts and hence any chance of attaining knowledge. If it is denied its function, it will no longer have either its definition or its reality; therefore, Ibn Rushd maintains that Ghazālī’s claim has no foundation:

“Now intelligence is nothing but the perception of things with their causes, and in this it distinguishes itself from all the other faculties of apprehension, and he who denies causes must deny the intellect. Logic implies the existence of causes and effects, and knowledge of these effects can only be rendered perfect through knowledge of their causes. Denial of cause implies the denial of knowledge, and denial of knowledge implies that nothing in this world can be really known, and that what is supposed to be known is nothing but opinion, that neither proof nor definition exist, and that the essential attributes which compose definitions are void. The man who denies the necessity of a ny item of knowledge must admit that even this, his own affirmation, is not necessary knowledge.” (p. 319)

The existence of voluntary agents is of course self-evident; but for Ibn Rushd an agent is anything that can exert an influence on an object, even without intervention of the will, as is the case with an inanimate body such as fire. Therefore, to affirm that natural causes can only be considered natural in a figurative sense is an egregious error or, as he puts it, “fallacy on fallacy” (p. 95). If a man were to die in a fire, he pertinently points out, no one would think of saying that the fire burned him “metaphorically.”

Moreover, if it were indeed true that we form judgments from habit alone and not from reasonable deduction, we could never be certain of anything, concerning either this world or the divine realm; constant doubt would thus be our lot since we should have no means of discernment:

“Everything would be the case only by supposition, and there would be no wisdom in the world from which it might be inferred that its agent was wise.” (p. 320)

For Ibn Rushd it is essential to perceive that the world has a logical structure, because he believes that knowledge of God can be attained through the observation of nature; the existence of order and harmony in the world and its laws bears witness to the perfect nature of the Being who manifested it. Therefore, if all natural events were caused by an unpredictable and arbitrary divine will,

“there would no longer, even for the twinkling of an eye, be any permanent knowledge of anything, since we suppose such an agent to rule existents like a tyrannical prince who has the highest power…of whom no standard or custom is known to which reference might be made.” (p. 325)

At the same time as responding systematically to each of Ghazālī’s arguments, Ibn Rushd is attempting to reassure his readers of the essential orthodoxy of philosophy. He claims that Ghazālī misjudges it and “ascribes to the philosophers theories which they do not hold.” (p. 96) It is wrong for instance to think that philosophy sees the world as eternal and uncreated, for in reality it is undergoing “everlasting production:”

“The philosopher’s theory, indeed, is that the world has an agent acting from eternity and everlasting, i.e. converting the world eternally from non-being into being.”

This concept of “non-being” is very close to the theologians’ “nihil,” from which, according to them, the world was created; moreover, the eternal transformation of the world out of non-being into being sounds very much like Ghazālī’s assertion that God intervenes constantly in nature. Nonetheless, one important difference remains with respect to the dogma on creation, namely, that Ibn Rushd does not state that the world came into existence at a definite point in time. Therefore, his theory is one of emanation rather than of creation, and this cannot find acceptance by the theologians. However, he affirms elsewhere that the world was indeed created, not through any arbitrariness of the Divine Will, but rather as a necessary act:

“Creation is an act of God. He created the world providentially, not by chance. The world is well ordered and is in a state of the most perfect regularity, which proves the existence of a wise Creator. Causality is presupposed.”[23]

On the question of miracles, Ibn Rushd is more emphatic; for him these are events which cannot be apprehended by reason but which must be acknowledged as authentically divine in origin, and for him the greatest of miracles is the Koran,

“the existence of which is not an interruption of the course of nature assumed by tradition…but its miraculous nature is established by way of perception and consideration for every man. This miracle is far superior to all others.” (p. 315)

In another treatise, he explains his reason for believing that the Koran is miraculous:

“The Laws of doctrine and practice contained in it are not of a sort that could possibly be discovered by a learning process, but only by inspiration.”[24]

Since the Koran does not interfere with natural laws, Ibn Rushd has no trouble explaining its miraculous nature; but he confesses himself impotent in the face of other kinds of miracles, and he relinquishes reason as he passes in at the door of Revelation, for there are barriers which he admits it cannot cross:

“As to the objection which Ghazālī ascribes to the philosophers over the miracle of Abraham, such things are only asserted by heretical Muslims. The learned among the philosophers do not permit discussion or disputation about the principles of religion, and he who does such a thing, according to them, needs a severe lesson…Of religious principles it must be said that they are divine things which surpass human understanding, but must be acknowledged although their causes are unknown.” (p. 322)

With respect to the miracle of Abraham, it seems that Ibn Rushd could have argued convincingly that if it were not in fire’s nature to burn, God would not have ordered it to be “coolness and peace for Abraham;”[25] by such an example, taken directly from the Koran, he could have refuted Ghazālī. Now it is perhaps over the question of miracles more than any other problem that the philosopher’s weakness becomes apparent. Since reason is unable to demonstrate miraculous occurrences, it simply abandons any attempt to explain them; but in fact the extra-ordinary nature of miracles does not necessarily preclude knowledge of their causes.

Finally, although the argumentation on either side is more complex than has been presented here, the foregoing debate between Ghazālī and Ibn Rushd could be reduced to a simple question of difference in perspectives, or rather in approaches, each of which is valid in its own domain. In order to affirm the absolute Oneness and Incomparability of God, as manifested in the Koran, Ghazālī stresses the discontinuity of all that is “other” than Him; this accounts for his rejection of natural causality as necessary, since to accept it would allow the world to have an existence seemingly independent from God. Given His attribute of Omnipotence, God cannot logically be prevented from intervening in the world at every instant: “There is no objection to admitting that anything may be possible for God” (p. 324), therefore the world’s organization is not inherent to it but is divinely ordained.

If Ghazālī’s arguments reach the threshold of absurdity at times, it is because he is attempting to demonstrate the undemonstrable, with the inevitable result that logic is to some extent sacrificed in the process. As a theologian, moreover, he is bound by dogmatic restrictions, since he has to expound the orthodox views of Islam, as strictly defined by tradition, and which must be accessible to the majority of believers. Yet it cannot be denied that he succeeds in making a forceful point inasmuch as he sees beyond the apparent reality of the physical world to the profound reality lying at its origin, whereas Ibn Rushd considers the physical world to be as real as the divine realm.

Ghazālī’s reasoning takes for its point of departure the highest order of reality, while on the contrary Ibn Rushd—as an Aristotelian philosopher—takes his starting point in the material world. Believing that the nature of God can be demonstrated according to physical laws, he seeks to attain knowledge of the Divine by firmly grasping material reality, then by reasoning through analogy, with the assumption that the same types of connection are to be found in higher levels of existence. Despite the justifications he offers for his method, it is understandable that this way of proceeding should have appeared dangerous to the theologians. In fact, Ibn Rushd’s views have led some scholars to the erroneous view that he was undertaking to defend science against religion;[26] but he could not have had this in mind, since his whole purpose was to attain to knowledge of God through knowledge of nature. As he himself admitted, the art of philosophy could be a threat to right belief if it were put into the wrong hands and pursued inadequately; but for the wise, it could only be a door opening onto a greater knowledge of reality, and hence of truth. Therefore, philosophy could not really be in conflict with theology, since both expounded the same truth seen in different lights, the Islamic revelation being vast enough to allow for several visions of a reality which is ultimately one.


[1] This was before Ghazālī turned to Sufism.

[2] Better known in the western world under his latinized name Averroes.

[3] Although it did see a resurgence in Eastern Islam through the Ishrāqī school of Illuminationism, with Suhrawardī.

[4] Al-Kindī, in his “On First Philosophy,” quoted by Seyyed Hossein Nasr in “The Meaning and Role of ‘Philosophy’ in Islam,” in Actas del V Congreso internacional de filosofia medieval (Madrid: Editora Nacional, 1979), I, p. 64.

[5] Koran 2:269; quoted by Nasr, p. 64.

[6] Al-Dārimī, Muqaddimah, p. 34; quoted by Nasr, p. 64.

[7] Nasr, An Introduction to Islamic Cosmological Doctrines (Cambridge: Harvard University Press, 1964), p. 167; Science and Civilization in Islam (Cambridge: Harvard University Press, 1968), p. 293.

[8] Averroes, On the Harmony of Religion and Philosophy, trans. by George F. Hourani (London: Luzac & Co., 1961), p. 70.

[9] Ibid., pp. 44-5. As a jurist, Ibn Rushd holds the view that rational speculation, which reaches its perfection with demonstrative syllogism, is fully legitimate according to the methods used in law.

[10]  Koran 59: 2. Pickthall translates it: “So learn a lesson, O ye who have eyes.” It belongs to a chapter which refers to “the exile of the Banū Nadir, a Jewish tribe of Madinah (for treason and projected murder of the Prophet) and the confiscation of their property.” Mohammed Marmaduke Pickthall, The Meaning of the Glorious Koran (New York: New American Library), p. 392. Certainly, Ibn Rushd’s conclusion here was derived by means other than deductive reasoning.

[11] Averroes, On the Harmony of Religion and Philosophy, p. 50.

[12] Ibid., p. 71.

[13] Averroes’ Tahāfut al-Tahāfut (“The Incoherence of the Incoherence”), trans. by Simon van den Bergh (Oxford: University Press, 1954), I, p. 215.

[14] Averroes, On the Harmony of Religion and Philosophy, p. 71.

[15] Averroes’ Tahāfut al-Tahāfut, p. 315.

[16] Ibid., p. 152.

[17] Averroes, On the Harmony of Religion and Philosophy, p. 70.

[18] Renan was one of the scholars who argued against Ibn Rushd’s sincerity. Cf. Arnaldez, in his article on Ibn Rushd, in the Encyclopaedia of Islam, New Edition (London: Luzac & Co., 1971), III, p. 911.

[19] Averroes’ Tahāfut al-Tahāfut, p. 95. Henceforth, all references to this work will be cited in the body of the article.

[20] Although Ghazālī is also concerned with man’s freedom of will and the body’s resurrection, the discussion here will not cover these issues.

[21] Here it could be asked what distinguishes the miraculous from the natural, because the word “miracle” would then be devoid of meaning.

[22] Koran: 21:68-9.

[23] From “Al-Kashf‘an Manāhij al-Adillah,” as quoted by Ahmed Fouad El-Ehwany, in A History of Muslim Philosophy, M. M. Sharifed. (Wiesbaden: Otto Harrassowitz, 1963), I, p. 549.

[24]  From “Manāhij,” p. 100, 8-9, as quoted by Hourani in On the Harmony of Religion and Philosophy, p. 115, note 192.

[25] Koran 21:69.

[26]  El-Ehwany, p. 557.

Original editorial inclusion that followed the essay in Studies:
Endeavoring to find a simile
for life and death,
I think of ice and water,
water hardening into ice,
ice melting back to water;
as death becomes inevitably life,
life turns to death again;
one cannot wound the other—
each makes the other beautiful


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