Abu Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī (/ælˈkɪndi/; Arabic: أبو يوسف يعقوب بن إسحاق الصبّاح الكندي; Latin: Alkindus; c. 801–873 AD) was an Arab[3][4][5][6][7] Muslim philosopher, polymath, mathematician, physician and musician. Al-Kindi was the first of the Islamic peripatetic philosophers, and is hailed as the "father of Arab philosophy".[8][9][10]

Portrait of Al-Kindi
Bornc. 801
Diedc. 873 (aged approximately 72)
Baghdad, Abbasid Caliphate (now in Iraq)
EraIslamic Golden Age
RegionIslamic philosophy
Main interests
Philosophy, Islamic theology, logic, ethics, mathematics, physics, chemistry, psychology, pharmacology, medicine, metaphysics, cosmology, astrology, music theory, Islamic theology (kalam)

Al-Kindi was born in Kufa and educated in Baghdad.[11] He became a prominent figure in the House of Wisdom, and a number of Abbasid Caliphs appointed him to oversee the translation of Greek scientific and philosophical texts into the Arabic language. This contact with "the philosophy of the ancients" (as Hellenistic philosophy was often referred to by Muslim scholars) had a profound effect on him, as he synthesized, adapted and promoted Hellenistic and Peripatetic philosophy in the Muslim world.[12] He subsequently wrote hundreds of original treatises of his own on a range of subjects ranging from metaphysics, ethics, logic and psychology, to medicine, pharmacology,[13] mathematics, astronomy, astrology and optics, and further afield to more practical topics like perfumes, swords, jewels, glass, dyes, zoology, tides, mirrors, meteorology and earthquakes.[14][15]

In the field of mathematics, al-Kindi played an important role in introducing Indian numerals to the Islamic world, and subsequently, relabeled as Arabic numerals, to the Christian world, along with Al-Khwarizmi.[16] Al-Kindi was also one of the fathers of cryptography.[17][18] Building on the work of Al-Khalil (717–786),[19] Al-Kindi's book entitled Manuscript on Deciphering Cryptographic Messages gave rise to the birth of cryptanalysis, was the earliest known use of statistical inference,[20] and introduced several new methods of breaking ciphers, notably frequency analysis.[21][22] Using his mathematical and medical expertise, he was able to develop a scale that would allow doctors to quantify the potency of their medication.[23]

The central theme underpinning al-Kindi's philosophical writings is the compatibility between philosophy and other "orthodox" Islamic sciences, particularly theology. And many of his works deal with subjects that theology had an immediate interest in. These include the nature of God, the soul and prophetic knowledge.[24] But despite the important role he played in making philosophy accessible to Muslim intellectuals, his own philosophical output was largely overshadowed by that of al-Farabi and very few of his texts are available for modern scholars to examine.