Farabi

Abū Naṣr al-Fārābī, known in the West as Alpharabius (c. 872– between 14 December 950 and 12 January 951), was a polymath and one of the greatest scientists and philosophers of the Islamic world in his time. He was also a cosmologist, logician, musician, psychologist and sociologist.

Logic
Though he was mainly an Aristotelian logician, he included a number of non-Aristotelian elements in his works. He discussed the topics of future contingents, the number ####and relation of the categories, the relation between logic and grammar, and non-Aristotelian forms of inference. He is also credited for categorizing logic into two separate groups, the first being "idea" and the second being "proof". Al-Farabi also considered the theories of conditional syllogisms and analogical inference, which were part of the Stoic tradition of logic rather than the Aristotelian. Another addition Al-Farabi made to the Aristotelian tradition was his introduction of the concept of poetic syllogism in a commentary on Aristotle's Poetics.

Music and sociology
Farabi wrote books on early Muslim sociology and a notable book on music titled Kitab al-Musiqa (The Book of Music). According to Seyyed Hossein Nasr and Mehdi Aminrazavi: the book of Kitab al-Musiqa is in reality a study of the theory of Persian music of his day although in the West it has been introduced as a book on Arab music. He presents philosophical principles about music, its cosmic qualities and its influences. Al-Farabi's treatise Meanings of the Intellect dealt with music therapy, where he discussed the therapeutic effects of music on the soul.

Philosophy
As a philosopher, Al-Farabi was a founder of his own school of early Islamic philosophy known as "Farabism" or "Alfarabism", though it was later overshadowed by Avicennism. Al-Farabi's school of philosophy "breaks with the philosophy of Plato and Aristotle [... and ...] moves from metaphysics to methodology, a move that anticipates modernity", and "at the level of philosophy, Alfarabi unites theory and practice [... and] in the sphere of the political he liberates practice from theory". His Neoplatonic theology is also more than just metaphysics as rhetoric. In his attempt to think through the nature of a First Cause, Alfarabi discovers the limits of human knowledge". Al-Farabi had great influence on science and philosophy for several centuries, and was widely regarded to be second only to Aristotle in knowledge (alluded to by his title of "the Second Teacher") in his time. His work, aimed at synthesis of philosophy and Sufism, paved the way for the work of Ibn Sina (Avicenna). Al-Farabi also wrote a commentary on Aristotle's work, and one of his most notable works is Al-Madina al-Fadila where he theorized an ideal state as in Plato's The Republic. Al-Farabi represented religion as a symbolic rendering of truth, and, like Plato, saw it as the duty of the philosopher to provide guidance to the state. Al-Farabi departed from the Platonic view in that he regarded the ideal state to be ruled by the prophet-imam, instead of the philosopher-king envisaged by Plato. Al-Farabi argued that the ideal state was the city-state of Medina when it was governed by the prophet Muhammad as its head of state, as he was in direct communion with Allah whose law was revealed to him. Influenced by the writings of Aristotle, in The Ideas of the Citizens of the Virtuous City and other books, Al-Farabi advanced the view that philosophy and revelation are two different modes of approaching the same truth.

Physics
Al-Farabi is also known for his early investigations into the nature of the existence of void in Islamic physics. In thermodynamics, he appears to have carried out the first experiments concerning the existence of vacuum, in which he investigated handheld plungers in water. He concluded that air's volume can expand to fill available space, and he suggested that the concept of perfect vacuum was incoherent.

Philosophical thought
The main influence on al-Farabi's philosophy was the neo-Aristotelian tradition of Alexandria. A prolific writer, he is credited with over one hundred works. Amongst these are a number of prolegomena to philosophy, commentaries on important Aristotelian works (such as the Nicomachean Ethics) as well as his own works. His ideas are marked by their coherency, despite drawing together of many different philosophical disciplines and traditions. Some other significant influences on his work were the planetary model of Ptolemy and elements of Neo-Platonism, particularly metaphysics and practical (or political) philosophy (which bears more resemblance to Plato's Republic than Aristotle's Politics). Al-Farabi as well as Ibn Sina and Averroes have been recognized as Peripatetics(al-Mashsha’iyun) or rationalists(Estedlaliun) among Muslims. However he tried to gather the ideas of Plato and Aristotle in his book "The gathering of the ideas of the two philosophers". According to Adamson, his work was singularly directed towards the goal of simultaneously reviving and reinventing the Alexandrian philosophical tradition, to which his Christian teacher, Yuhanna bin Haylan belonged. His success should be measured by the honorific title of "the second master" of philosophy (Aristotle being the first), by which he was known. Interestingly, Adamson also says that he does not make any reference to the ideas of either al-Kindi or his contemporary, Abu Bakr al-Razi, which clearly indicates that he did not consider their approach to Philosophy as a correct or viable one.

Farabi's cosmology is essentially based upon three pillars: Aristotelian metaphysics of causation, highly developed Plotinian emanational cosmology and the Ptolemaic astronomy. In his model, the universe is viewed as a number of concentric circles; the outermost sphere or "first heaven", the sphere of fixed stars, Saturn, Jupiter, Mars, the Sun, Venus, Mercury and finally, the Moon. At the centre of these concentric circles is the sub-lunar realm which contains the material world. Each of these circles represent the domain of the secondary intelligences (symbolized by the celestial bodies themselves), which act as causal intermediaries between the First Cause (in this case, God) and the material world. Furthermore these are said to have emanated from God, who is both their formal and efficient cause. This departs radically from the view of Aristotle, who considered God to be solely a formal cause for the movement of the spheres, but by doing so it renders the model more compatible with the ideas of the theologians.