Iranian philosophy 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, "Zarathustra's philosophy entered to influence Western tradition through Judaism, and therefore on Middle Platonism."

Ancient Greek philosophy arose in the 6th century BC. Philosophy was used to make sense of the world using reason. It dealt with a wide variety of subjects, including astronomy, epistemology, mathematics, political philosophy, ethics, metaphysics, ontology, logic, biology, rhetoric and aesthetics. Greek philosophy continued throughout the Hellenistic period and later evolved into Roman philosophy.