One can speak of Arabic philosophy with regard to historical phenomena that occurred in different cultural and religious spheres, which also differed according to the historical period and the geographical area in which they were located, but which are basically united by the use of the same language: Arabic. The term includes both the so-called Islamic or Arabic-Islamic philosophy, which originated in the medieval Near East of the Muslim religion, and the so-called Arabic-Christian philosophy, which adopted Arabic as a language of expression following its close contacts with the Islamic world, together with the traditional language of the Christian Near East: Syriac. These two phenomena were followed by a third, represented by the so-called Judeo-Arabic philosophy; the latter, however, is better included within the sphere of Jewish philosophy.
Also including the philosophy that should be more properly defined as Syriac, the Arab-Christian philosophy comes to be placed in the Mesopotamian area (Syria, Iraq) in the 6th-13th centuries. The authors who were part of it all shared their belonging to two Christian sects, present in that area during the Middle Ages, but on two diametrically opposed theological positions: the Jacobite Church and the Nestorian Church, one of which made the divine nature of Jesus Christ prevail, and the other his human nature. To the formerly belonged philosophers who expressed themselves mainly in the Syriac language, and who dedicated themselves above all to questions of logical and metaphysical-theological nature, that touched on the fundamental themes of their religion: among them, we can remember Sergius of Rēsh ‛ainā (d. 536), the commentators on Aristotelian logic active around 700 (Athanasius of Balad, George Bishop of the Arabs), and the theologians James of Edessa (d. 708), Moses bar Kēfā (d. 903) and John of Dara (9th century); in the 13th century the two monophysite authors Jacob bar Shakkō (d. 1241) and more importantly Gregory Bar Hebraeus (1225-1286), the greatest representative of this philosophy, wrote various philosophical-scientific encyclopedias.
In the 9th-10th centuries some of these philosophers, who worked in Baghdad, continued the work of their predecessors, though expressing themselves in Arabic: this is the case of Yahyā Ibn ‛Adī (d. 974) and Abū ‛Ālī Ibn Zur‛a (943-1008). On the other hand, there were authors belonging to the Nestorian Church who, starting from the 9th century, mainly translated philosophical and scientific texts from Greek to Syriac and from Syriac to Arabic, on behalf of Muslim readers: among them, Hunain Ibn Ishāq and his disciples, active in Baghdad between about 850 and 910, need to be mentioned.
The phenomenon of translations represented an important starting point for the development of Arab-Islamic philosophy: it was precisely on texts of Greek philosophy and science (especially the works of Aristotle and his commentators, but also writings of Hippocrates and Galen, Ptolemy and Euclid, and at least some of Plato’s works and the main authors of the Neoplatonic school: Plotinus, Porphyry and Proclus), translated into Arabic by Christian authors between about 800 and 1000, that the Muslim philosophers of the Middle Ages laid the foundations of their autonomous thought. Arab-Islamic philosophy began in Iraq, and in particular in Baghdad, during the first half of the 9th century, and from there it spread over the following three centuries – which represented the moment of its maximum development – first in Iran, and later in other neighboring countries, going as far as North Africa; to characterize it was mainly the need to harmonize philosophy as a rational study of reality with the contents of the Islamic religious tradition. The first manifestation of an Arab-Islamic philosophy took place with the Iraqi al-Kindī, known as the «philosopher of the Arabs» par excellence. He devoted himself to the organization of a series of paraphrastic-interpretative translations into Arabic and produced, among other things, fundamental sources of medieval Neo-Platonic philosophy such as the Ūtūlūğīyā (Theology) of the pseudo-Aristotle and the Kalām fī mahd al-khā’ir («Discourse on the Pure Good», better known as Liber de causis), as well as Arabic versions of a series of Greek writings by Alexander of Aphrodisiah or to him attributed. He himself, being basically a Neoplatonist, was also interested in aspects of Aristotelian metaphysics: an interest that he revealed in his main philosophical work, al-Falsafa al-ūlā («First philosophy»).
In his numerous philosophical writings, he touched on themes of metaphysical, physical, psychological (he was the first to introduce into Arab philosophy the question of the nature of human intellect in his Risāla fī l-‘aql, «Epistle on the intellect») and ethical (inspired by the stoic ideal of apathy); he also wrote a terminological dictionary, which laid the foundations for the thought of his successors. One can also speak of Neoplatonism in the case of two other important authors of the Arab-Islamic medieval philosophy of the first half of the 10th century. Abū Bakr al-Rāzī was mainly a doctor, but he also devoted himself to philosophy, developing themes and doctrines inspired by Platonism and Pythagoreanism, with fundamentally anti-Aristotelian positions (he was among the first, in medieval philosophy, to deny the Aristotelian concepts of finite space and time); he was, on the whole, a rationalism not devoid of elements taken from non-Islamic religions (Mazdeism, Manichaeism, Buddhism, and Hinduism), which brought him into conflict with some aspects of Islam and led to the destruction of many of his works. The Rasā’il Ikhwān al-safā’ («Epistles of the Brethren of Purity»), a philosophical-scientific encyclopedia in 52 treatises, was undoubtedly oriented towards Neo-Platonism, probably assumed through the interpretation given by the Islamic sect of the Ismailis; it is thought that the anonymous author can be identified with the Spanish Muslim Abū l-Qāsim Maslama al-Maǵrīṭī, editor of esoteric writing, Ġāyat al-ḥakīm («The aim of the wise»).
At the same time as Neo-Platonism, an Aristotelianism developed in the Islamic world, based on the commentary on the Stagirite’s writings: a commentary that, among the many exponents of this Aristotelianism, took on the character of an interpretative summary, or a paraphrase adapted to the needs of the reader, or a precise literal commentary of the text (reported entirely in Arabic translation), or even a philosophical encyclopedia. The first commentator, called the «second master» after Aristotle, was al-Fārā’bī. His epitomes of Aristotle’s logic had a considerable influence on medieval Arab-Islamic and Jewish philosophy; his famous epistemological treatise, Ihsā’ al-‘ulūm («The enumeration of the sciences»), followed an original scheme, which connected Aristotle to the Islamic religious sciences; his treatise on the intellect reanalyzed and developed the analogous work of al-Kindī. He was still also known for his ethical-political works, among which al-Madīna al-fādila («The virtuous city») stands out: in this work, he started from a brief exposition of theology, metaphysics, physics, and human psychology, to then explain his own idea of the ideal state, governed by an imā’m with the assistance of a senate of philosophers. A rationalist philosopher even in his approach to the Islamic religion, al-Fārā’bī created a school in Baghdad that continued to deepen and perfect his thinking until the middle of the 11th century.
The so-called «New Aristotle» was the most successful medieval philosopher in the Arab-Islamic world: Avicenna. Originally known as al-Fārā’bī from Central Asia and as a very fertile author (he was famous in the Islamic world as a mystic, and also in the Latin world as a doctor), in his numerous philosophical works he treated the contents of the logical, physical and metaphysical writings of the Stagirite in a systematic way, building encyclopedias in which he adapted the thought of the Greek philosopher to his own needs and his own religion, in an attempt to reconcile the Aristotelian tradition and the doctrines of Islam: an attempt that did not exclude new proposals on issues such as the nature of the human soul, or that of time and space. His two best-known and most popular philosophical encyclopedias in the Middle Ages, al-Šifā’ («The Cure», in 10 volumes) and al-Nağāt («The salvation», in three parts), were part of this purpose, which he followed in other writings; among them, we should remember al-Falsafa al-mašrīqīya («The oriental philosophy»), where philosophy was not based so much on rational and syllogistic concepts (according to the Aristotelian scheme) as it was on intuitive ones. Avicenna didn’t leave behind a simple school, but a true and proper orientation of thought, which found many supporters in the following centuries, but also several opponents.
This ‘Avicennism’ was based on an interpretation of Avicenna as the creator of an innovative Aristotelianism (this category included the Jewish philosopher converted to Islam Abū l-Barakāt al-Baghdādī, d. 1164), and assumed the characters of «Illuminationism», i.e. neo-Platonizing theosophy where Avicenna’s thought was altered and adapted (this is the case of authors such as Sihāb al-dīn al-Suhrawardī, d. 1191). Avicennism, which seemed in many ways in contrast with the theological doctrine of Sunni Islam, provoked within the latter the defense of the official Ashʿari theology, represented in the 11th century by its greatest exponent, the Persian al-Ġāzālī. He, after having studied at length the thought of Avicenna, exposed and refuted it in a sort of trilogy of a philosophical and theological character. In the first of the three works, Mi’yār al-‘ilm («The Criterion of Knowledge»), he expounded Aristotle’s logic, adapting its contents to the needs of Islamic theology; in the second, Maqāsid al-falāsifa («The Aims of the Philosophers»), he summarized the contents of the logic, physics, and metaphysics of Avicenna’s Daneš nameh («The Book of Knowledge»), to criticize them; this criticism, which aimed to find the irrationality of twenty points of Avicenna’s physics and metaphysics, was carried out in the third work, Tahāfut al-falāsifa («The Incoherence of the Philosophers»).
In the wake of al-Ġāzālī followed a Persian theologian and philosopher, Fakhr al-dīn al-Rāzī. In the 12th century, the Arab-Islamic philosophy that was founded, like that of al-Fārā’bī and Avicenna, on the interpretation of Aristotle’s thought, had a surprising, though ephemeral, development in Muslim Spain (today’s Andalusia) and in the nearby Maghreb; thanks to this development, that philosophy exerted a considerable influence not so much on Islamic thought in general as on medieval Jewish philosophy and Latin scholasticism. It was represented by three authors. Ibn Bā’ggia (d. 1138-1139) was, first of all, a commentator (his commentaries on Aristotle’s logic, physics and psychology remain, systematic and rationally ordered), but he was also the author of original philosophical writings: the best known was Tadbīr al-mutawahhid («The rule of the solitary»), that developed a theme already present in al-Fārā’bī by describing the ethical and intellectual characteristics of the ideal philosopher. Ibn Ṭufàil (1110 – 1185), perhaps a pupil of Ibn Bā’ggia, substantially deepened the idea of the latter, presenting in his philosophical work Hayy ibn Yaqzān («The living son of the vigilant») a theme partially mentioned in some of Avicenna’s writings, but which he approached differently.
The ideal image that Ibn Ṭufàil presented here was that of a man who, left alone with himself from birth, is able to develop his own philosophy, fundamentally Aristotelian in character, which then when he confronts with others, proves to have reached substantially the same conclusions as revealed religion. Averroes, a philosopher, and doctor as well as a judge, represented the best-known Arab-Islamic thinker in the Jewish and Christian West, thanks to the medieval and Renaissance translations, in Hebrew and Latin, of many of his works, at the origin of the development of ‘Averroism’. He became especially famous as a commentator on almost all of Aristotle’s work, to which he dedicated, between around 1160 and 1195, commentaries that were wither summarizing (the Epitomes), paraphrasing (the Middle Commentary), or literal (the Long Commentary). On many points he was in contrast with the interpretations of these works given by the Arab authors before him: he wanted to return, in logic as in physics and metaphysics, to the true Aristotle, intending to free him from medieval interpretations and instead willingly accept some of the interpretations given by Greek commentators (from Alexander of Aphrodisiah onwards).
Moreover, Averroes did not avoid tackling, particularly in his Fasl al-maqāl («The Decisive Treatise»), the difficult question of the relationship between Aristotelian philosophy and the Islamic religion, formulating a doctrine which, though being often erroneously defined «of double truth», was instead based on the idea that philosophy and religion, if correctly interpreted, will reach substantially the same conclusions. Islamic philosophy did not end with Averroes, even if its developments remained relatively unknown. Between around 1200 and 1800, there were several authors who, in different ways, should be ascribed to it. Among them, we can mention: the Spanish Ibn Sab ̔ī ΄n (1217-1270), who explored themes of Averroes’s thought in a rationalistic key; ‛Abd al-Latīf al-Baghdādī (d. 1231), who returned to the Neoplatonism of al-Kindī; the Persian Nāṣir al-dīn al-Ṭūsī (1201-1274), who was among other things a commentator of Avicenna; the Tunisian Ibn Khaldū΄n (1332-1406), the first historical philosopher of the Arab world; the Persian Mūllā Sadrā Širazī (1571/1572-1640), who was the protagonist of a revival of interest in medieval Arab-Islamic philosophy in Safavid Persia. It seems more difficult to talk about a real Arab-Islamic philosophy in the contemporary age, from the beginning of the 19th century onwards. With the disappearance of the points of reference represented by traditional authors, tendencies of thought have arisen in the Arab world, during the 20th century, which was fundamentally interested in the purely political problems of Islamic nations: Arab nationalism, Arab socialism. Islam has continued to represent an essential fact in Arab countries; but it has tended to be in opposition to the modern idea of philosophy as a secular discipline, freed from relations with religion: an idea that has not established itself much in the Arab world.