The Beginning of Systematic Philosophical Writings
Also during al-Mamun's reign, in addition to these translations (which formed the groundwork of Arabic-Islamic philosophy), the first genuine philosopher of Islam,Yaqub ibn Ishaq al-Sabah al-Kindi (795–866), started his literary activity. A prolific encyclopedic author to whom some three hundred works are attributed, al-Kindi was the first champion of Greek philosophy, which was approached with some suspicion in traditional and popular circles as a foreign and pagan import. Al-Kindi believed that the study of philosophy, regardless of its foreign extraction, should not be feared by the true believer, because philosophy's chief subject of inquiry is the True One, source of all being and unity. Rather than conflicting with religious or Islamic truth, al-Kindi held, philosophy actually reinforces that truth. More explicitly than any other Muslim philosopher before or since, Al-Kindi proclaimed his adherence to the principal Muslim articles of faith, including the existence of God, the creation of the world out of nothing and in time, the resurrection of the body, and the truth of prophetic revelation. According to al-Kindi, these articles, embodied in the Quran, could be demonstrated philosophically and their truth dialectically reinforced. They belong to that body of divine wisdom, which surpasses human wisdom but is perfectly compatible with it. As a pioneering writer on philosophical subjects—which covered the entire range of classical learning, from logic to astronomy, ethics and metaphysics—al-Kindi was responsible for developing an adequate philosophical and scientific vocabulary that influenced his successors although it was later replaced by a more precise vocabulary.
The next outstanding writer on philosophical subjects was the great Persian physician-philosopher Abu Bakr al-Razi (ca. 865–between 923 and 935), who took a diametrically opposite stand to al-Kindi on the relationship between philosophy and revelation, generally referred to in Arabic sources as “prophethood.” Like al-Kindi, al-Razi was a great admirer of Greek philosophy. In Platonic-Socratic fashion, al-Razi saw in the study of philosophy the only means of liberating the soul from the bondage of the body and its ultimate release from the wheel of birth and rebirth. Accordingly, his chief ethical treatise is entitled Spiritual Physic (therapy), to serve as a counterpart of the bodily physic (conventional medicine). The greatest nonconformist in Muslim religious history, al-Razi repudiated the entire concept of revelation or prophethood as superfluous, because for him reason was perfectly competent on its own to lead to the discovery of truth and the cultivation of morals. More radical, perhaps, was his concept of the five eternal principles from which the world was originally fashioned: the Creator, the soul, matter, space, and time. Because most of these principles can be shown to have a basis in Plato's Timaeus, al-Razi should be regarded as Islam's greatest Platonist. He refers to Plato in his Spiritual Physic as the “master and leader of the philosophers,” whose theories of the soul, creation in time, and the ultimate liberation of the soul from the bondage of the body he incorporated into his own system through the study of philosophy. Al-Razi even defended in the strongest terms the Platonic theory of the transmigration of the soul, which was never in vogue in philosophical or theological circles. The only part of Plato's philosophy that al-Razi overlooked is politics. Later philosophers, such as Abu Nasr al-Farabi in the tenth century and Ibn Rushd in the twelfth century, inspired by Plato's Republic, either commented on or used it as a model in their political writings. For reasons unknown, al-Razi also seems to have overlooked in his some two hundred works another favorite Platonic discipline: mathematics.