Such a system involves ethical difficulties; it appears that there can be no responsibility if there is no connection between action and the act done. Al-Ash`ari replied that there is a unity in the will of God, so that cause and effect are not isolated as though independent atoms, but all is disposed according to a Divine plan. This answer, however, can hardly be regarded as adequate.
This system is an attempt to deal with the difficulties raised by philosophy, but al-Ash`ari considers it preferable that the difficulties should never be raised, and so strongly urges that the mysteries of philosophy should never be discussed with the multitude. We shall see the same conclusion set forth by the later philosopher of the West, but on a somewhat different ground; they regarded the mysteries of philosophy as containing the supreme truth, for which the multitude was not ripe, and so they should not be discussed publicly, as the people were not able to understand; but al-Ash`ari seems rather to regard these mysteries as likely to be not edifying, as introducing questions which are of small importance compared with the great truths of revelation.
The Ash`arite system thus described was completed by al-Baqilani (d. 403), but it did not become general until it was popularised by al-Ghazali in the East and by Ibn Tumart in the West.
Al-Mataridi, of Samarqand was a contemporary of al-Ash`ari, and reached very similar results. Amongst the points peculiar to al-Mataridi we may note (a) the attribute of creating has been an attribute of God from all eternity, but this attribute is distinct from the thing created; (b) Creatures have certain choice of action, and for the things done by this choice they are rewarded or punished; good actions are only done by the pleasure (rida) of God, but bad actions are not always by His pleasure; (c) Ability to do the action goes with the will and the act, so that the creature cannot have an action imposed on him as a task which is not in his power.
He agrees with al-Ash`ari in holding that the world and all it contains have been created by God from nothing: it consists of substances and attributes. The substances exist in themselves, either as compounds, such as bodies, or as non-compounds, as essences which are indivisible. Attributes have no separate existence, but depend for their existence on bodies or essences. God is not essence, nor attribute, nor body, nor anything formed, bounded, numbered, limited, nor compounded. He cannot be described by mahiya (quiddity), nor kayfiya (modality); He does not exist in time or place, and nothing resembles Him or is outside His knowledge or power. He has qualities from all eternity existing in His essence; they are not He nor is He other than they.
For some time the Ash`arites had to meet keen opposition and even persecution, and it was not until the middle of the 5th cent. that they came to be admitted generally as orthodox Muslims. Their triumph was assured in 459 A.H., when Nizam al-Mulk, the wazir of Alp Arslan, founded at Baghdad the Nizamite academy as a theological college of Ash`arite teaching. Still the Hanbalites raised occasional riots, and demonstrated against those whom they regarded as free thinkers; but these were put down by authority, and in 516 the Khalif himself attended the Ash`arite lectures. The Mu`tazilites were now merely a survival; as broad church theologians they had fallen into general disrepute in the eyes of the orthodox, and they were equally disliked by the philosophers as defective in their adherence to the Aristotelian system. The educated fell now into three broad groups: on the one hand were the orthodox, who came under the influence of al-Ash`ari or al-Mataridi; on the other were those who accepted the doctrines of the philosophers, and in the third place were those who rejected all philosophy, and confined their attention solely to Qur´an tradition and the canon law, and who should not be excluded from the ranks of the educated, although their studies ran in somewhat narrow lines.
The final triumph of the Ash`arite theology was the work of al-Ghazali (d. 505). He was born at Tus in 450 (= 1058 A.D.); early left an orphan he was educated by a Sufi friend, and then attended the school at Naisabur. As his education progressed he cut loose from Sufi influence and became an Ash`arite, and in 484 he was appointed president of the Nazimite Academy at Baghdad. Gradually, however, he became a prey to spiritual unrest, and in 488 resigned his post and retired to Syria, where he spent some years in study and the practices of devotion. In 499 he returned to active work as a teacher in the Nazimite Academy at Naisabur, where he became the leader of a modified Ash`arite system strongly leavened by mysticism, which we may regard as the final evolution of orthodox Muslim theology.
Al-Ghazali, following al-Ash`ari, taught that philosophical theory cannot form the basis of religious thought, thus opposing the position of the philosophers. By revelation only can the primary essentials of truth be attained. Philosophy itself is no equal or rival of revelation: it is no more than common sense and regulated thinking, which may be employed by men about religion or any other subject; at best it acts as a preservative against error in deduction and argument, the primary material for which, so far as religion is concerned, can be furnished only by revelation. But against this he appears also as the transmitter of the teaching already given, by al-Qushayri, which introduced the mysticism of the Sufis into orthodox Islam. Revelation indeed is given by means of the Qur´an and tradition, and it is sufficient to accept what is thus revealed, but the ultimate truth of revelation can be tested and proved only by the experience of the individual. So far as men are concerned this is possible by means of ecstasy whereby one becomes a knower (`arif), and receives assurance and enlightenment by direct communication from God. The soul of man differs from all other created things; it is essentially spiritual, and so outside the categories which are applicable only to material things. The soul has been breathed into man by God (Qur. 15, 29; 38, 72), and this is comparable to the way in which the sun sends out its rays and gives warmth to those things on which its rays rest. The soul, which has no dimension, shape, or locus, rules the body in the same way as God rules the world, so that the body is a microcosm reproducing the conditions of the world. The essential element of this soul is not the intelligence which is concerned with the bodily frame, but the will: just as God is primarily known not as thought or intelligence, but as the volition which is the cause of creation. Thus God cannot be considered as the spirit animating the world, which is the pantheistic position, but as volition outside the world which has willed it to be.
The aim of scholastic theology is to preserve the purity of orthodox belief from heretical innovation: “God raised up a school of theologians and inspired them with the desire to defend orthodoxy by means of a system of proofs adapted to unveil the devices of the heretics and to foil the attacks which they made on the doctrines established by tradition” (Al-Ghazali: Confessions). Aristotle himself was an unbeliever using arguments he should not, but, in spite of his errors, his teaching as expounded by al-Farabi and Ibn Sina is the system of thought which comes nearest to Islam (id.). Because of its unavoidable difficulties and the grave errors contained in Aristotle and his Arabic commentators men are not to be encouraged to read philosophy (id.).