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Islamic Rationalism

Rationalism is the attitude of appealing to reason as the fundamental justification of knowledge or beliefs. Imadaldin Al-Jubouri describes the disputes among early Islamic scholars about the limits of what can be known through science and rationality.

The early period of rationalism in Islamic thought was led by a school of thinkers known as the Mutazilites (‘isolationists’), in the second half of the first century of Islam (7th Century, CE). It is very difficult to research the Mutazilites’ early years in the Hijaz, Egypt and Iraq, except for what was mentioned by historians such as al-Tabari and al-Nobikhti, who said that “they involve themselves only with science, knowledge and worship.”

The first group of Mutazilite thinkers were Mabad al-Juhni (d.702 CE), al-Ju’d ibn Drhim (d.721), the Damascene Ghaylan (d.743), and Jahm ibn Safwan (d.745). Their fundamental philosophical ideas were:

1. The denial of fate. They did not believe in fate, because man has free will and is responsible for his own actions.

2. A denial that the attributes of God are knowable. To them, God is impervious to characterisation by His creatures.

3. The Qur’an is created. They believed the Qur’an had been created, and it is not the uncreated Word of God.

These ideas were against Islamic dogma, so all these men were executed.

In Basra, Wasil ibn Ata (699-749) founded a ‘rationalist’ school to represent Mutazilite thought and to teach Muslims new methods of thinking. He asserted that the intellect is a way to faith, to know God, a way to distinguish between good and evil, and the only criterion to understand the Sharia (Islamic law). Hence, Mutazilites said that “intellect is before quotation,” and they praised the intellect considerably. They contended with other Muslim schools, particularly the Hashawaites and Dhahirites, who believed that the intellect had no role in the Sharia. Truly, it was hard work for Mutazilite thinkers to free Muslim minds from the shackles of dogma and formal teaching methods. The main problem was that each school used Qur’anic verses to support its own attitude. For instance, the fatalists used the following verses:

“Say: ‘Nothing shall ever happen to us except what God has ordained for us.’” (9:51) “For God bestows His abundance without measure on whom He will.” (2:212) “And no aged man is granted a length of life nor is a part cut off from his life, but it is in the Book. Surely that is easy for God.” (35:11)

While some others denied the existence of fate. They indicated different verses, such as:

“Then shall anyone who has done an atom’s weight of good, see it! And anyone who has an atom’s weight of evil, shall see it.” (99:7-8) “We showed him the Way: Whether he be grateful or ungrateful.” (76:3) “And whatever of good ye give, be assured God knoweth it well.” (2:273)

It was the same with those who either believed or denied that the attributes of God are knowable.

To overcome these apparent differences in Qur’anic verses, Mutazilites aimed to interpret them, but in their own way. However, al-Allaf (753-840) played the important role of putting questions of philosophy into Mutazilite thinking, especially concerning the divine and nature. To al-Allaf, the Divine Self is one; and knowledge, mercy, sight, hearing, omnipotence etc ­– all these are no more than the Divine Self itself, and not attributes of it. He also believed that atoms are the ultimate aspect of matter, that the body consists of atoms, and that bodily movement creates space. Thus movement is achieved with two places and times, while stillness is achieved in one place at two times, because time does not stop its current.

Although the Mutazilites agreed on specific principles, they had some differences. For instance, al-Allaf’s student al-Nazzam (d.836) deemed that molecules are endlessly divisible, that there is no matter without movement, and that stillness does not exist. Further, opposites can exist in one body, and things can emerge from one another. Another student of al-Allaf, al-Jubbai (d.915) differed from his tutor in nineteen questions, as mentioned by the historian al-Malti (d.988).

Generally, Mutazilites dealt with many Islamic problems, religious, philosophical, political and social, but through a rational perspective. Although Alkindi (800-868) was pro-Mutazilite, he turned the wheel completely in the direction of philosophy. As a scholar and a translator with an interest in Greek philosophy, Alkindi used Aristotle’s logic to support Islamic ideas. Though influenced by Aristotle’s philosophy, Alkindi adopted the Neoplatonic take, which fitted with his own adherence to Islam.


Alfarabi (870-950) brought to ripeness what Alkindi had sowed, and established Islam’s first philosophical doctrines. In The Virtuous City and other works, Alfarabi affirmed that the senses were vital to human knowledge, believing with Aristotle that “all knowledge gets into the soul by means of the senses.” He agreed with Aristotle that if a man lost one sense he would lose one science. The senses perceive only parts, but together these parts can provide whole experiences of the truth. The most important of these experiences are related to knowledge and the principles of demonstration. Intellect is nothing but the sum of experience: the more experiences the soul has, the more highly the intellect is developed. But man cannot acquire knowledge merely by direct contact between the senses and material things; the soul’s powers must intervene [cf Kant – Ed].

Alfarabi explains to us: “It has been thought the intellect gets at the forms of things when sensible perception of perceptible things takes place without intervention. It is not like that. Between them [thought and the things] are intermediaries, so the senses approach perceptible things, obtain their forms and transmit what is in it [ie the forms] to the common sense, to the imagination and to the faculty that distinguishes them and prepares them correctly for the intellect.” For Alfarabi the intellect was “a sort of shape in matter arranged to accept the forms of sensible things.” This intellect is at first only potential, becoming actual when it perceives the forms of external bodies. This translation from potential into actual reality is not determined by any human act, but effected by a higher intellect which is always actual. This is the ‘active intellect’, or ‘the intellect of the orbiting moon,’ which gives light to the potential [human] intellect, allowing it to become actual just as the sun’s light allows human eyes to see. There is yet another intellect above the active intellect, and another one above that; and so on until the Divine Intellect is reached. When the human intellect is connected with the active intellect, sensory perception becomes rational perception and the soul gains further understanding of the meaning of existence.

Above sensory knowledge and rational knowledge then, there exists illuminating knowledge. The forms of things are known by this active intellect and cannot be passed on without emanation from the active intellect. By being illuminated by the active intellect the forms are thereby emancipated from the trappings of material existence, so those who perceive the forms may achieve connection with the divine light. This sort of knowledge is for philosophers and prophets only. Alfarabi’s ideas about knowledge are mixed up with Revelation theory and Sufism in Islam, as well as Plato’s philosophy and Neoplatonism. Alfarbi, like most Muslim philosophers, derived his idea of emanation from Plotinus’ theory of emanation and reflection.


Avicenna (980-1037) was a student of Alfarabi’s writings. Avicenna distinguished himself by his uniqueness in clarification, explanation and subtle digression. This made his philosophy spread like wildfire from nation to nation. Avicenna appeared in the period when the Islamic empire started to lose power and learning in Europe started to revive. He thus became more important in the European universities than in the Muslim world. For instance, his work The Canon of Medicine, translated into Latin by Gerard of Cremona (1114-1187), strongly influenced the teaching of medical science until the sixteenth century.

In The Book of Salvation and other works, Avicenna said that the source of human knowledge is emanation from the active intellect, through which the forms of things come from God to man. The human body and its senses are no more than the means to prepare the human intellect to accept this emanation. On this point Avicenna agrees with Alfarabi and disagrees with Aristotle, saying that in acquiring knowledge the evidence of our senses is secondary. Rather Avicenna, like Alfarabi before him, asserted that rational knowledge conforms with eternal essences which do not change. An eternal truth exists independently of the existence of individuals “as an intellectual form by itself.” To know these things, emanation proceeds from the Intellect of God to the orbital intellects, then down to the human intellect, which alone can conceive things as a whole.

Avicenna divided knowledge into three kinds: knowledge by nature, knowledge by abstracts and knowledge by intuition:

A) Knowledge by nature. This is knowledge of a priori principles. For example, ‘a whole is greater than a part’, ‘one is half of two’, ‘two things each of which is equal to some other thing are also equal to each other’, etc.

B) Knowledge by abstracts. This is knowledge acquired by means of abstracting the form from a material object. This requires more effort than knowledge by nature, and in order to acquire it man must reach the level of ‘utilised intellect’.

There are four kinds of abstraction:

1. Sensory perception. Common sense extracts the forms from the material world ­– quantity, quality, position etc. This sort of perception does not completely abstract the form from matter, as it requires the material object to conceive the form.

2. Imaginary perception. The imagination clearly conceives the form of objects in a more sophisticated way than in sensory perception. If the matter disappears, the form remains constant in the imagination. Although the form is completely abstracted from matter, it still has strong links to the material.

3. Illusory perception. Illusion deals with only ideas of things, not material things at all, and is thus a higher form of abstraction than imagination. It still cannot rid the experience of the form totally of its material appendages, because it is still in the partial category, classifying forms according to a perception of the physical world, albeit an illusory perception.

4. Rational perception. Here the intellect abstracts forms completely from matter. For example, rationality separates the form or essential idea of ‘man’ from quantity, quality, etc. The intellect alone can perceive abstracts totally apart from material objects, such as God and angels. Such perception cannot be complete unless illuminated by the active intellect.

C) Knowledge by intuition. People have different levels of intuition. Some may be able to reach a level at which they do not need to connect with the active intellect to acquire knowledge, as though they already knew everything themselves intuitively. Such readiness of intuition at the very highest level no-one except a prophet can achieve. The prophet’s power of intuition is called ‘holy intellect’ and is the highest power of the human mind. People can generally acquire knowledge either by nature or by means of abstraction, or both. Very few, however, have possessed all knowledge intuitively: this is for the prophets alone.


Alma’arri (973-1057) represents the other side of distinctively Islamic philosophy. Immersed in chronic pessimism, he had a somewhat disturbed outlook on humanity. According to him, man has nothing but his intellect to assist him in his bewilderment with his world. As for religions and what the prophets have said, it’s all utter nonsense which cannot satisfy any man of intellect. Alma’arri’s reverence for the human intellect was frequently expressed in the most exaggerated terms. For him the intellect was “a prophet emanating from divine brightness.” Here are some of his reflections on the sanctity of the intellect:

“You naive ones have been assigned an intellect,
So ask it; each intellect is a prophet.
You have left the light of your intellect unfollowed.
God has bestowed the brightness of intellect upon you.”

Alma’arri tells us to use a rational measure for everything that we have been told by narrators or traditions: “Consult the intellect and leave the others. Intellect is the best adviser ever.” Nevertheless, the intellect is unable to search out metaphysics:

“I asked my intellect, but received no reply, so I said to him, ask men; they either won’t know or say that they can answer, but are prejudiced; when I prompted them to syllogisms, they showed and admitted their helplessness.”

Although Alma’arri had doubts in every metaphysical subject, whether philosophical or religious, he did not doubt the existence of God the Creator:

“Certainly God is true,
So blame your doubtful souls. God is true; who ponders upon Him,
Will know certitude and believe in miracles.”


Scepticism for Alma’arri was more psychological than rational. But Algazel (1058-1111) adopted the principle of scepticism in search of certainty. Nonetheless, the result was the same: Algazel concluded that the intellect is unable to search out metaphysics. In any case, as Algazel affirms in M’iraj al-Qudos (‘Ascent of Holiness’), “Sharia is external intellect and intellect is internal code. Thereby they are both in cooperation and unified”: as God said, “Brightness upon brightness” (that is, the brightness of the intellect with the brightness of the Sharia).

Algazel adhered to this approach, the product of his relentless pursuit of the truth, attaining a realisation of truth after much scepticism, in response to the various Islamic sects and schools, such as the Mutazilites, Hashawites and Dhahrites. For Algazel there was no contradiction between the intellect and the Sharia – they were not separate but united. The intellect stood helpless in the face of metaphysics only because no evidence offering certain knowledge was available to the mind in this context; a purely intellectual approach to metaphysics could lead only to useless doubts. We should not however misinterpret Algazel’s attitude by thinking he wanted to discredit the intellect altogether. His point was only that the intellect was inadequate for this particular task.

In his book The Incoherence of the Philosophers, Algazel said inspiration and revelation should act as the intellect’s supporters whenever any problem to which the intellect could not provide a final answer left it helpless. From this he argued that the intellect should be an interpreter of revelation and inspiration – so it was imperative to use the intellect for understanding the Sharia. He shared this approach with the Mutazilites, but he valued intellect more moderately than they, although he insisted on applying logic. Algazel regarded logic as an essential tool for explaining the facts of faith because an intellect armed with logic would be able to avoid falling into error. However, he warned against digging too deeply in pursuit of pure facts, on the grounds that the intellect without revelation was not always able to grasp the truth, especially in religious and divine issues.

According to Algazel, in theological issues, Plato, Aristotle and Plotinus, and those Muslims who followed them, particularly Alfarabi and Avicenna, were all confused and contradicted each other. He asserted that this demonstrated the insufficiency of the intellect (in this field alone). His aim was to achieve a balance and a moderation that would protect religious thinking against any unwarranted innovation or extremism.

Algazel was particularly opposed to founding dogma upon rational thought alone, or confining religion within the principles of logic. According to him the intellect was capable of dealing with mathematics, geometry, logic, physics and astronomy, but not with religion or metaphysical issues, since religion and the facts of faith must flood forth from the heart. The intellect and the heart were designed to deal with knowledge from different sources, the intellect being designed for the theoretical and practical sciences, while the heart deals with religious intuition, spiritual taste and inner revelation. Having limited the capacities of the intellect and the heart in this way, Algazel inevitably ended up with some sharp distinctions in his philosophy.


Averroes (1126- 1198) was a jurist; both his father and grandfather were jurists too; so he was well set up to refute Algazel’s view of religion. In The Incoherence of the Incoherence Averroes charged Algazel with:

1. Relying on unconvincing ‘proofs’.

2. Warping other philosophers’ opinions so they would appear to support what he was saying, and omitting anything inconvenient to his arguments.

3. Writing malicious nonsense.

4. Not being a real philosopher.

To Averroes, learned wisdom and the Sharia are expressing a single truth in different ways, and therefore are not in conflict. Nor need there be dispute or dissension between their supporters, despite the apparent contradictions between them on the questions that had caused scholars such as Algazel to believe there was an irreconcilable difference between religious wisdom and philosophy. To Averroes, philosophy was no more than a means of investigating the world and the universe as proof of the Maker. The aim of philosophy was thus no different from the Sharia, despite their different approaches. Hence Averroes believed the Sharia did not prohibit rational thinking, but on the contrary supported it, as certain verses in the Qur’an made clear: “Then take admonition, O you with eyes” (59:2), for example, urged the use of rational analogy. “Do they not look in the dominion of the heavens and the earth and all things that God has created?” (7:185) recommended the thoughtful examination of all natural and cosmic things, as did, “Do they not look at the camels, how they are created? And at the heaven, how it is raised?” (88:17-18). The words, “And think deeply about the creation of the heavens and the earth” (2:191) express a special concern for people who remember God in thinking of His creation. There are many verses on this subject.

The Sharia, then, endorses rational consideration of everything in existence, deducing what was unknown from what is known. In other words, our consideration of reality should proceed by means of what the logicians call rational syllogisms. Of the various types of syllogism, the Sharia would clearly advocate the evidential syllogism. This should be considered the most productive type because it starts from a premise certain in itself (evidence) and thus leads to conclusions that cannot be untrue. The argumentative syllogism begins from a premise of supposition and is thus less effective, because its conclusions cannot be regarded as certain. The oratorical syllogism relies upon generally accepted premises to sway people’s feelings. The fallacy syllogism relies on premises appearing to be true but which lead only to unacceptable conclusions. It was important the Sharia should not be approached by the wrong method. The Qur’an says:

“Invite to the way of your Lord with wisdom and fair preaching, and argue with them in a way that is better. Truly, your Lord knows best who has gone astray from His Path, and He is the best aware of those who are guided.” (16:125)

According to Averroes, anyone who wished to deduce the existence of the Maker and achieve knowledge of Him by considering His creation must therefore first understand the various kinds of proof and be able to distinguish between them. He also said that theoretical research in religious matters could reach no correct deduction except by the use of logic. Thus the rational syllogism should not be rejected as heresy just because it had not been accepted during the early period of Islam. Juristic reasoning in all its various types had developed within Islam, and no-one had called that heresy. No prohibition should be considered to exist on seeking the help of the ancients, even if they were not Islamic, because ignoring an entire period of valuable research would be counterproductive. Logic was simply a useful tool to protect the mind from making mistakes; it had nothing specifically to do with who discovered it, or with the nature of their beliefs. There was no reason whatsoever to shun the ancients’ books (Greek philosophy) or the deductions therein: “If it was right we accepted it with pleasure and thanked them for that; if it was not right we had to point it out, warn of it and excuse ourselves from it.” The Sharia’s injunction to us to consider the creation in order to know the Maker shows that the Hashawites and other scholars were wrong in believing Muslims were prohibited from studying the books of the ancients. According to Averroes, there was no contradiction between religion and philosophy, since “the right does not contradict the right, but agrees with it and confirms it.”

Averroes believed that any apparent differences between the Qur’an and the conclusions reached using philosophical proofs could be resolved by means of proper research. A very similar process had already happened within Islam itself. Long before the problem of religion vs philosophy appeared, scholars had puzzled over apparent contradictions between Qur’anic verses. They had reconciled these apparent contradictions by making a distinction in certain texts between literal readings and real (‘inner’) meanings. This sort of reconciliation, called ‘interpretation,’ subsequently became the appropriate means of resolving the apparent contradictions between philosophy and religion. In short, the Sharia scholar used the principles of rational syllogism ‘inwardly,’ while the philosopher used it intellectually.

Ibn Khaldun

In spite of his experimental and scientific tendencies, ibn Khaldun (1332-1406) rejected Averroes’ attitude and championed Algazel’s treatment. In The Introduction, ibn Khaldun has philosophy lean on the intellect and on logical syllogisms, paying little direct attention to the material world. He believed the intellect to be incapable of fully understanding theology: theological subjects exist beyond the senses, so we cannot reach or prove them. Plato himself said that philosophy does not lead to certainty, but to supposition. What then was the benefit of philosophy if there could be no certainty in it?

Ibn Khaldun followed in Algazel’s footsteps in criticizing philosophers and rejecting their ideas, particularly in metaphysics. He considered to be false the philosophical idea that happiness consisted of a rational perception of the creation, on the grounds that happiness in the soul which does not require any agent such as sense-perception must be a far greater pleasure. Such a state of soul results not from meditation or science, but from ignoring the senses and forgetting all bodily perceptions. The Sufis frequently used just such means to attain a happiness they could not express. The philosophers claimed that anyone who succeeded in perceiving and connecting with the ‘active intellect’ would be happy. According to Aristotle and men such as Alfarabi, Avicenna and Averroes, such perception and connection must take place within the soul, without agency. This could not happen except by screening out the senses.

To ibn Khaldun the philosophers’ approach was thus inadequate to its real aim, and also contrary to the Sharia. All the philosophers had done was to arrange their arguments to achieve the appearance of philosophical excellence, rather than create anything properly called proof. Their syllogisms and syntheses were constructed according to the conditions they had derived in their logical works. But although the philosophers’ modes of proof were inadequate for every context, they were the best theoretical laws that could be derived.

This last statement shows that Averroes had as much effect as Algazel upon ibn Khaldun, who never dismissed the rights of the intellect, whatever its connection to religion. Like Algazel, ibn Khaldun regarded the intellect as incapable of understanding metaphysics unless the way of revelation and mysticism were followed first. Ibn Khaldun wrote, “The intellect is a balanced scale; its judgements are certitude, without falsehood – but you cannot attempt to weigh by it the issues of monotheism, the hereafter, the reality of prophecy, the reality of the divine, His attributes or any metaphysical issue. All of that is grabbing at the impossible.” There is of course a strange contradiction in ibn Khaldun’s attitude here in that, while criticizing philosophers and rejecting their ideas, he plunges deeply into philosophy himself.

Nevertheless, ibn Khaldun was well ahead of his time. His work and his principles of ‘experimenting’ and ‘seeing’ (comparison) as the only true measures of knowledge had a far greater effect in Europe than in the Islamic world. He was the last fitful true philosophic glow in Islamic civilization.

© I.M.N. Al-Jubouri 2006

Dr Imadaldin Al-Jubouri has written several books in Arabic and English, including his History of Islamic Philosophy.

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