Iranian philosophy (Persian? ) or Persian philosophy can be traced back as far as to Old Iranian philosophical traditions and thoughts which originated in ancient Indo-Iranian roots and were considerably influenced by Zarathustra's teachings. According to the Oxford Dictionary of Philosophy, the chronology of the subject and science of philosophy starts with the Indo-Iranians, dating this event to 1500 BC. The Oxford dictionary also states, "Zarathushtra's philosophy entered to influence Western tradition through Judaism, and therefore on Middle Platonism."
Throughout Iranian history and due to remarkable political and social changes such as the Arab and Mongol invasions of Persia, a wide spectrum of schools of thoughts showed a variety of views on philosophical questions extending from Old Iranian and mainly Zoroastrianism-related traditions, to schools appearing in the late pre-Islamic era such as Manicheism and Mazdakism as well as various post-Islamic schools. Iranian philosophy after Arab invasion of Persia, is characterized by different interactions with the Old Iranian philosophy, the Greek philosophy and with the development of Islamic philosophy. The Illumination School and the Transcendent Philosophy are regarded as two of the main philosophical traditions of that era in Persia.
See also Ancient Iranian Philosophy
The teachings of Zarathustra (Zoroaster) appeared in Persia at some point during the period 1700-1800 BCE. His wisdom became the basis of the religion Zoroastrianism, and generally influenced the development of the Iranian branch of Indo-Iranian philosophy. Zarathustra was the first who treated the problem of evil in philosophical terms. He is also believed to be one of the oldest monotheists in the history of religion. He espoused an ethical philosophy based on the primacy of good thoughts (andi?e-e-nik), good words (goftâr-e-nik), and good deeds (kerdâr-e-nik).
The works of Zoroaster and Zoroastrianism had a significant influence on Greek philosophy and Roman philosophy. Several ancient Greek writers such as Eudoxus of Cnidus and Latin writers such as Pliny the Elder praised Zoroastrian philosophy as "the most famous and most useful". Plato learnt of Zoroastrian philosophy through Eudoxus and incorporated much of it into his own Platonic realism. In the 3rd century BC, however, Colotes accused Plato's The Republic of plagiarizing parts of Zoroaster's On Nature, such as the Myth of Er.
Zarathustra was known as a sage, magician and miracle-worker in post-Classical Western culture, though almost nothing was known of his ideas until the late eighteenth century. By this time his name was associated with lost ancient wisdom and was appropriated by Freemasons and other groups who claimed access to such knowledge. He appears in Mozart's opera The Magic Flute ("Die Zauberflöte") under the variant name "Sarastro", who represents moral order in opposition to the "Queen of the Night". Enlightenment writers such as Voltaire promoted research into Zoroastrianism in the belief that it was a form of rational Deism, preferable to Christianity.
In 2005, the Oxford Dictionary of Philosophy ranked Zarathustra as first in the chronology of philosophers. Zarathustra's impact lingers today due in part to the system of rational ethics he founded called Mazda-Yasna. The word Mazda-Yasna is Avestan and is translated as "Worship of Wisdom" in English. The encyclopedia Natural History (Pliny) claims that Zoroastrians later educated the Greeks who, starting with Pythagoras, used a similar term, philosophy, or "love of wisdom" to describe the search for ultimate truth.
Little is known of the situation of philosophy during the time of the ancient Greek philosophers. We know that the Persian culture had influence on the creation of Stoic school of thought, but nothing has been left in Persian writings. The Athenians labelled any Greek speaking philosophers as Greek Philosophers whether or not they were of Greek origin and that is the biggest problem that has been carried down the centuries. Many of the so called Greek philosophers were born in Sicily known as Syracuse and were enemies of Athens. How an enemy of Athens is then considered a Greek philosopher is a falsehood. They were obviously of Persian origin and stolen by the Athenians as their own.
Manichaeism, founded by Mani, was influential from North Africa in the West, to China in the East. Its influence subtly continues in Western Christian thought via Saint Augustine of Hippo, who converted to Christianity from Manichaeism, which he passionately denounced in his writings, and whose writings continue to be influential among Catholic, Protestant, and Orthodox theologians. An important principle of Manichaeism was its dualistic cosmology/theology, which it shared with Mazdakism, a philosophy founded by Mazdak. Under this dualism, there were two original principles of the universe: Light, the good one; and Darkness, the evil one. These two had been mixed by a cosmic accident, and man's role in this life was through good conduct to release the parts of himself that belonged to Light. Mani saw the mixture of good and bad as a cosmic tragedy, while Mazdak viewed this in a more neutral, even optimistic way.
Mazdak (d. 524/528 CE) was a proto-socialist Persian reformer who gained influence under the reign of the Sassanian king Kavadh I. He claimed to be a prophet of God, and instituted communal possessions and social welfare programs.
Zurvanism is characterized by the element of its First Principle which is Time, "Zurvan", as a primordial creator. According to Zaehner, Zurvanism appears to have three schools of thought all of which have classical Zurvanism as their foundation:
Aesthetic Zurvanism which was apparently not as popular as the materialistic kind, viewed Zurvan as undifferentiated Time, which, under the influence of desire, divided into reason (a male principle) and concupiscence (a female principle).
Fatalistic Zurvanism resulted from the doctrine of limited time with the implication that nothing could change this preordained course of the material universe and that the path of the astral bodies of the 'heavenly sphere' was representative of this preordained course. According to the Middle Persian work Menog-i Khrad: "Ohrmazd allotted happiness to man, but if man did not receive it, it was owing to the extortion of these planets."
The intellectual tradition in Persia continued after Islam and was of great influence on the further development of Iranian Philosophy. The main schools for such studies were, and to some extents still are, Shiraz, Khurasan, Maragheh, Isfahan, Tehran.
In the Islamic Golden Age, due to Avicenna's (Ibn Sina's; born near Bukhara) successful reconciliation between Aristotelianism and Neoplatonism along with Kalam, Avicennism eventually became the leading school of Islamic philosophy by the 12th century. Avicenna had become a central authority on philosophy by then, and several scholars in the 12th century commented on his strong influence at the time:
"People nowadays [believe] that truth is whatever [Ibn Sina] says, that it is inconceivable for him to err, and that whoever contradicts him in anything he says cannot be rational."
Avicennism was also influential in medieval Europe, particularly his doctrines on the nature of the soul and his existence-essence distinction, along with the debates and censure that they raised in scholastic Europe. This was particularly the case in Paris, where Avicennism was later proscribed in 1210. Nevertheless, his psychology and theory of knowledge influenced William of Auvergne and Albertus Magnus, and his metaphysics influenced the thought of Thomas Aquinas.
Illuminationist philosophy was a school of Islamic philosophy founded by Shahab al-Din Suhrawardi in the 12th century. This school is a combination of Avicenna's philosophy and ancient Iranian philosophy, along with many new innovative ideas of Suhrawardi. It is often described as having been influenced by Neoplatonism.
Transcendent Theosophy is the school of Islamic philosophy founded by Mulla Sadra in the 17th century. Mulla Sadra bought "a new philosophical insight in dealing with the nature of reality" and created "a major transition from essentialism to existentialism" in Islamic philosophy, several centuries before this occurred in Western philosophy.
Philosophy was and still is a popular subject of study in Iran. Previous to Western style universities, philosophy was a major field of study in religious seminaries. Comparing the number of philosophy books currently published in Iran with that in other countries, Iran possibly ranks first in this field but it is definitely on top in terms of publishing philosophy books. 
On the diversity and expansion of philosophy in Iran, Khosrow Bagheri has stated "One part of philosophical endeavor in Iran today, and perhaps the main one, is concerned with the local philosophy which is dominated by the school of Mulla Sadra. He has provided a philosophy in line with the old metaphysical inclination but in the feature of a combination of mysticism, philosophy, and the Islamic religious views. On the other hand, a relatively strong translation movement has been shaped in which the Iranian readers are provided by some of the important sources of contemporary philosophy in Persian including both the analytic and continental traditions. In the former, Wittgenstein, Searle, and Kripke, and in the latter, Nietzsche, Heidegger, and Foucault can be mentioned. There have also been concentrations on a local polar contrast between Popper and Heidegger, and, due to the religious atmosphere, on philosophy of religion." 
Among journals being published in Iran on philosophy there are FALSAFEH-The Iranian Journal of Philosophy[permanent dead link] published by the department of philosophy of the University of Tehran since 1972 and Hikmat va Falsafeh published by Allamah Tabataba'i University in Tehran, Ma'rifat-e Falsafeh published by the Imam Khomeini Education and Research Institute in Qom, and many others. Also worthy of mention is the journal, Naqd o Nazar published by Daftar Tablighat in Qom, which often includes articles on philosophical topics and other issues of interest to religious thinkers and intellectuals.
It is important to note that Sufism has had a great amount of influence on Iranian/Persian philosophy.
In the history of Islamic philosophy, there were a few Persian philosophers who had their own schools of philosophy: Avicenna, al-Farabi, Shahab al-Din Suhrawardi and Mulla Sadra. Some philosophers did not offer a new philosophy, rather they had some innovations: Mirdamad, Khajeh Nasir and Qutb al-Din Shirazi belong to this group. Some philosophers had new narration of existing philosophies: Agha Ali Modarres is an example of such philosophers.
`Abdu'l-Bahá, son and successor of the founder of the Bahá'í Faith, has explained the Bahá'í philosophy in the work Some Answered Questions. This text has been analyzed by Bahá'í scholars Ian Kluge and Ali Murad Davudi.