When Islam took over the Middle East it came into contact with a flourishing local culture heavily influenced by Greek thought. As far as philosophy was concerned, neoplatonism was the leading approach. For example, many of the most important neoplatonists such as Plotinus, Porphyry, and Proclus had studied in Alexandria, a city conquered by the Muslims in 642. A number of key texts became important when translated into Arabic. These were the Theology of Aristotle, in fact mainly parts of Plotinus's Enneads and the Liber de causis, based on Proclus's Elements of Theology. Also popular among philosophers were the extensive commentaries on Aristotle by Alexander of Aphrodisias, Themistius, and others—commentators imbued with the values of neoplatonism to some extent. One significant aspect of neoplatonism was the idea that Plato and Aristotle did not differ much on important issues, together with the doctrine of emanation and a cosmology that has the world being produced out of one being or principle. The translation project that transmitted Greek manuscripts into Arabic introduced a good many of these ideas and doctrines into the Islamic world, and so philosophy in the sense of falsafa or Peripatetic philosophy became identified in the first few centuries with neoplatonic philosophy.
The Main Doctrines
The emphasis on the unity of the creator may well have found a welcoming reception by Muslim thinkers, and it is certainly there strongly in Islamic neoplatonism. One of the central issues is how there came to be many things in existence when really there exists only one absolute being or principle. An explanation is that the One thinks and through thinking brings other things into existence, because once it thinks it realises that it is a thinking thing, and this brings about a mental bifurcation in its unity, a bifurcation that leads to the production of a range of beings that exist either closer or more distantly from it. The more perfect and abstract they are, the closer they are, the less perfect and the more material are more distant.
Another issue was how God related to the world. If God is identified with the One, then the usual account is that he creates the world by emanation, not production. God thinks about himself and through a variety of stages other things are brought into existence, but it would be an interference with God's perfection were he to know about any of these lesser things. The only thing he should think about is himself, and so the world comes about as an indirect effect of this form of thought. An implication of this is that the world is eternal, because God has always existed, and so has always thought about himself. He did not suddenly start thinking, since it is part of his essence to think. Because God is eternal, his thinking must be eternal, and whatever stems from it eternal also. As can be seen, these are all doctrines that do not fit neatly within the framework of a religion such as Islam. The Qurʾan suggests, although does not explicitly state, that God created the world at a particular time, when he wanted to, and it states that he knows everything that goes on in the world. The indirect account of creation as emanation in neoplatonism seems different from the understanding of creation in the Qurʾan.
The Main Philosophers
The first Islamic philosopher to construct a thoroughly neoplatonic philosophy was al-Fārābī, and he led the way to Ibn Sīnā (Avicenna), who produced the most developed such theory. They both described emanation as consisting of ten intellects that link the Necessary Being or One with our world, where the active intellect (often identified with the moon) is the highest level of thought that we can attain. The political implications of the theory are important too. Those who can attain the active intellect are the appropriate rulers, and prophets are those who are able to think at the level of the active intellect, or come into contact with it at least occasionally. This enables them to understand the organization of the world because the active intellect is the most abstract form of thought that human beings can attain, and once it is combined with the facts we observe in the world the prophet can easily predict what is going to happen. For one thing, the organization of the world, according to Ibn Sīnā, is in terms of necessity, so the pattern of existence is something that may be understood rationally by an advanced thinker.
Attacks on Neoplatonism
Neoplatonism came under attack by Muḥammad al-Ghazālī, who criticized it in his "Refutation of Philosophy" both for being heretical and also for being invalid philosophically. He picked out in particular the theses that God cannot know individual things, that the world is eternal and that bodily resurrection is inconceivable. The latter follows from neoplatonism due to its prioritization of the soul over the body, and the principle that the material aspects of human beings are not important enough to survive death. The account of immortality in the Qurʾan is clearly material, and the idea that only souls survive death does not seem to fit it. God would not know individual things because he has no sense machinery and he is separated from the everyday activities of this world. Yet as al-Ghazālī argues, how can he punish and reward us on the day of judgement if he has no idea what we do in this world? He rightly points to a range of ideas that really give God little to do, whereas the God of the Qurʾan is directly involved in our everyday affairs.
But these are theological points, and al-Ghazālī also uses the arguments of his opponents to refute them. He tries to disprove the whole neoplatonic apparatus, importing God's will to keep nature in operation as a unified system instead of necessity. He argues in particular that causal necessity is only an idea we have and we could easily think of different connections, or no connections at all, between familiar causes and effects. This really does threaten the whole neoplatonic system, because this involves necessary connections between events, so that when one thing occurs, something else has to occur also. Al-Ghazālī makes a lot of use of imagination here, using thought experiments to try to show that the putative necessary connections are not necessary at all. When Ibn Rushd (Averroes) responded to his attack in his "Refutation of the Refutation" he was fighting with one hand tied behind his back, because Ibn Rushd disapproved of many of the neoplatonic principles as incompatible with the thought of Aristotle, where his main allegiance lay. Ibn Rushd was able to discern many of the divergences between Aristotle and neoplatonism, but in order to defend philosophy as such he was obliged to defend neoplatonism, because this was the main form of philosophy in the Islamic world at that time. Islamic neoplatonism also had a considerable effect on Ismaʿili thought, and on ishrāqī (illuminationist) thought. The esoteric Brethren of Purity (Ikhwān al-Safaʾ) were thoroughly imbued with neoplatonic ideas, although often not very orthodox ones.
Decline of Islamic Neoplatonism
Neoplatonism also came under attack by the mystics in Islam who saw its limited access to God as a significant problem. The highest we can come to God is to come into contact with the active intellect, a range of abstract thinking that is really a long way from God. Mystics tend to advocate a much closer connection to God and criticized neoplatonists for their view on this. However, they could use aspects of the theory to explain different levels of reality and their interconnections, although these had to be suitably reinterpreted of course along Sufi lines. Similarly some ishrāqī thinkers replaced the language of the levels of intelligences and worlds with levels of illumination, while at the same time arguing against neoplatonism itself. Neoplatonic philosophy went into a serious decline in the Arab world after the twelfth century, but interest in it continued up to now in the Persian cultural sphere, because its contribution to ishrāqī and Sufi thought was acknowledged and respected.
