Early Islamic philosophy or classical Islamic philosophy is a period of intense philosophical development beginning in the 2nd century AH of the Islamic calendar (early 9th century CE) and lasting until the 6th century AH (late 12th century CE). The period is known as the Islamic Golden Age, and the achievements of this period had a crucial influence in the development of modern philosophy and science; for Renaissance Europe, the influence represented “one of the largest technology transfers in world history.”. This period starts with al-Kindi in the 9th century and ends with Averroes (Ibn Rushd) at the end of 12th century. The death of Averroes effectively marks the end of a particular discipline of Islamic philosophy usually called the Peripatetic Arabic School, and philosophical activity declined significantly in Western Islamic countries, namely in Islamic Spain and North Africa, though it persisted for much longer in the Eastern countries, in particular Persia and India where several schools of philosophy continued to flourish: Avicennism, Illuminationist philosophy, Mystical philosophy, and Transcendent theosophy.
Some of the significant achievements of early Muslim philosophers included the development of a strict science of citation, the isnad or "backing"; the development of a method of open inquiry to disprove claims, the ijtihad, which could be generally applied to many types of questions (although which to apply it to is an ethical question); the willingness to both accept and challenge authority within the same process; recognition that science and philosophy are both subordinate to morality, and that moral choices are prior to any investigation or concern with either; the separation of theology (kalam) and law (shariah) during the early Abbasid period, a precursor to secularism; the distinction between religion and philosophy, marking the beginning of secular thought; the beginning of a peer review process; early ideas on evolution; the beginnings of the scientific method, an important contribution to the philosophy of science; the introduction of temporal modal logic and inductive logic; the beginning of social philosophy, including the formulation of theories on social cohesion and social conflict; the beginning of the philosophy of history; the development of the philosophical novel and the concepts of empiricism and tabula rasa; and distinguishing between essence and existence.