(1). All bodies, they argue, are one in so far as the phenomenal fact of their existence is concerned. But in spite of this unity, their qualities are different and even opposed to each other. We are, therefore, driven to postulate an ultimate cause in order to account for their empirical divergence.
(2). Every contingent being needs a cause to account for its existence. The Universe is contingent; therefore it must have a cause; and that cause is God. That the Universe is contingent, they proved in the following manner. All that exists in the Universe, is either substance or quality. The contingence of quality is evident, and the contingence of substance follows from the fact that no substance could exist apart from qualities. The contingence of quality necessitates the contingence of substance; otherwise the eternity of substance would necessitate the eternity of quality. In order fully to appreciate the value of this argument, it is necessary to understand the Ash‘arite theory of knowledge. To answer the question, "What is a thing?" they subjected to a searching criticism the Aristotelian categories of thought, and arrived at the conclusion that bodies have no properties in themselves[70:1]. They made no distinction of secondary and primary qualities of a body, and reduced all of them to purely subjective relations. Quality too became with them a mere accident without which the substance could not exist. They used the word substance or atom with a vague implication of externality; but their criticism, actuated by a pious desire to defend the idea of divine creation, reduced the Universe to a mere show of ordered subjectivities which, as they maintained like Berkeley, found their ultimate explanation in the Will of God. In his examination of human knowledge regarded as a product and not merely a process, Kant stopped at the idea of "Ding an sich", but the Ash‘arite endeavoured to penetrate further, and maintained, against the contemporary Agnostic-Realism, that the so called underlying essence existed only in so far as it was brought in relation to the knowing subject. Their atomism, therefore, approaches that of Lotze[71:1] who, in spite of his desire to save external reality, ended in its complete reduction to ideality. But like Lotze they could not believe their atoms to be the inner working of the Infinite Primal Being. The interest of pure monotheism was too strong for them. The necessary consequence of their analysis of matter is a thorough going idealism like that of Berkeley; but perhaps their instinctive realism combined with the force of atomistic tradition, still compels them to use the word "atom" by which they endeavour to give something like a realistic coloring to their idealism. The interest of dogmatic theology drove them to maintain towards pure Philosophy an attitude of criticism which taught her unwilling advocates how to philosophise and build a metaphysics of their own.
But a more important and philosophically more significant aspect of the Ash‘arite Metaphysics, is their attitude towards the Law of Causation[72:1]. Just as they repudiated all the principles of optics[72:2] in order to show, in opposition to the Rationalists, that God could be visible in spite of His being unextended, so with a view to defend the possibility of miracles, they rejected the idea of causation altogether. The orthodox believed in miracles as well as in the Universal Law of Causation; but they maintained that, at the time of manifesting a miracle, God suspended the operation of this law. The Ash‘arite, however, starting with the supposition that cause and effect must be similar, could not share the orthodox view, and taught that the idea of power is meaningless, and that we know nothing but floating impressions, the phenomenal order of which is determined by God.
Any account of the Ash‘arite metaphysics would be incomplete without a notice of the work of Al-Ghazālī (d. 1111 A.D.) who though misunderstood by many orthodox theologians, will always be looked upon as one of the greatest personalities of Islam. This sceptic of powerful ability anticipated Descartes[73:1] in his philosophical method; and, "seven hundred years before Hume cut the bond of causality with the edge of his dialectic"[73:2]. He was the first to write a systematic refutation of philosophy, and completely to annihilate that dread of intellectualism which had characterised the orthodox. It was chiefly his influence that made men study dogma and metaphysics together, and eventually led to a system of education which produced such men as Shahrastānī, Al-Rāzī and Al-Ishrāqī. The following passage indicates his attitude as a thinker:—
"From my childhood I was inclined to think out things for myself. The result of this attitude was that I revolted against authority; and all the beliefs that had fixed themselves in my mind from childhood lost their original importance. I thought that such beliefs based on mere authority were equally entertained by Jews, Christians, and followers of other religions. Real knowledge must eradicate all doubt. For instance, it is self-evident that ten is greater than three. If a person, however, endeavours to prove the contrary by an appeal to his power of turning a stick into a snake, the performance would indeed be wonderful, though it cannot touch the certainty of the proposition in question"[75:1]. He examined afterwards, all the various claimants of "Certain Knowledge" and finally found it in Ṣūfīism.
With their view of the nature of substance, the Ash‘arite, rigid monotheists as they were, could not safely discuss the nature of the human soul. Al-Ghazālī alone seriously took up the problem, and to this day it is difficult to define, with accuracy, his view of the nature of God. In him, like Borger and Solger in Germany, Ṣūfī pantheism and the Ash‘arite dogma of personality appear to harmonise together, a reconciliation which makes it difficult to say whether he was a Pantheist, or a Personal Pantheist of the type of Lotze. The soul, according to Al-Ghazālī, perceives things. But perception as an attribute can exist only in a substance or essence which is absolutely free from all the attributes of body. In his Al-Madnūn[75:2], he explains why the prophet declined to reveal the nature of the soul. There are, he says, two kinds of men; ordinary men and thinkers. The former who look upon materiality as a condition of existence, cannot conceive an immaterial substance. The latter are led, by their logic, to a conception of the soul which sweeps away all difference between God and the individual soul. Al-Ghazālī, therefore, realised the Pantheistic drift of his own inquiry, and preferred silence as to the ultimate nature of the soul.
He is generally included among the Ash‘arite. But strictly speaking he is not an Ash‘arite; though he admitted that the Ash‘arite mode of thought was excellent for the masses. "He held", says Shiblī (‘Ilmal-Kalām, p. 66.), "that the secret of faith could not be revealed; for this reason he encouraged exposition of the Ash‘arite theology, and took good care in persuading his immediate disciples not to publish the results of his private reflection". Such an attitude towards the Ash‘arite theology, combined with his constant use of philosophical language, could not but lead to suspicion. Ibn Jauzī, Qāḍī ‘Iyāḍ, and other famous theologians of the orthodox school, publicly denounced him as one of the "misguided"; and ‘Iyāḍ went even so far as to order the destruction of all his philosophical and theological writings that existed in Spain.
It is, therefore, clear that while the dialectic of Rationalism destroyed the personality of God, and reduced divinity to a bare indefinable universality, the antirationalist movement, though it preserved the dogma of personality, destroyed the external reality of nature. In spite of Nazzām's theory of "Atomic objectification"[77:1], the atom of the Rationalist possesses an independent objective reality; that of the Ash‘arite is a fleeting moment of Divine Will. The one saves nature, and tends to do away with the God of Theology; the other sacrifices nature to save God as conceived by the orthodox. The God-intoxicated Ṣūfī who stands aloof from the Theological controversies of the age, saves and spiritualises both the aspects of existence, and looks upon the whole Universe as the self-revelation of God—a higher notion which synthesises the opposite extremes of his predecessors. "Wooden-legged" Rationalism, as the Ṣūfī called it, speaks its last word in the sceptic Al-Ghazālī, whose restless soul, after long and hopeless wanderings in the desolate sands of dry intellectualism, found its final halting place in the still deep of human emotion. His scepticism is directed more to substantiate the necessity of a higher source of knowledge than merely to defend the dogma of Islamic Theology, and, therefore, marks the quiet victory of Ṣūfīism over all the rival speculative tendencies of the time.
Al-Ghazālī's positive contribution to the Philosophy of his country, however, is found in his little book—Mishkātal-Anwār—where he starts with the Quranic verse, "God is the light of heavens and earth", and instinctively returns to the Iranian idea, which was soon to find a vigorous expounder in Al-Ishrāqī. Light, he teaches in this book, is the only real existence; and there is no darkness greater than non-existence. But the essence of Light is manifestation: "it is attributed to manifestation which is a relation"[78:1]. The Universe was created out of darkness on which God sprinkled[79:1] his own light, and made its different parts more or less visible according as they received more or less light. As bodies differ from one another in being dark, obscure, illuminated or illuminating, so men are differentiated from one another. There are some who illuminate other human beings; and, for this reason, the Prophet is named "The Burning Lamp" in the Qur’ān.
The physical eye sees only the external manifestation of the Absolute or Real Light. There is an internal eye in the heart of man which, unlike the physical eye, sees itself as other things, an eye which goes beyond the finite, and pierces the veil of manifestation. These thoughts are merely germs, which developed and fructified in Al-Ishrāqī's "Philosophy of Illumination"—Ḥikmatal-Ishrāq.