Abu'l-Barakāt al-Baghdādī

Abu'l-Barakāt Hibat Allah ibn Malkā al-Baghdādī (; c. 1080 – 1164 or 1165 CE) was an Islamic philosopher, physician and physicist of Jewish descent from Baghdad, Iraq. Abu'l-Barakāt, an older contemporary of Maimonides, was originally known by his Hebrew birth name Baruch ben Malka and was given the name of Nathanel by his pupil Isaac ben Ezra before his conversion from Judaism to Islam later in his life.

His writings include the anti-Aristotelian philosophical work Kitāb al-Muʿtabar ("The Book of What Has Been Established by Personal Reflection"); a philosophical commentary on the Kohelet; and the treatise "On the Reason Why the Stars Are Visible at Night and Hidden in Daytime". Abu'l-Barakāt was an Aristotelian philosopher who in many respects followed Ibn Sina, but also developed his own ideas. He proposed an explanation of the acceleration of falling bodies by the accumulation of successive increments of power with successive increments of velocity.

His thought influenced the Illuminationist school of classical Islamic philosophy, the medieval Jewish philosopher Ibn Kammuna, and the medieval Christian philosophers Jean Buridan and Albert of Saxony.

Isaac, the son of the Abraham Ibn Ezra and the son-in-law of Judah Halevi,

Motion Al-Baghdadi was a follower of the scientific and philosophical teachings of Ibn Sina. According to Alistair Cameron Crombie, al-Baghdadi

proposed an explanation of the acceleration of falling bodies by the accumulation of successive increments of power with successive increments of velocity.

According to Shlomo Pines, al-Baghdadi's theory of motion was thus

the oldest negation of Aristotle's fundamental dynamic law [namely, that a constant force produces a uniform motion], [and is thus an] anticipation in a vague fashion of the fundamental law of classical mechanics [namely, that a force applied continuously produces acceleration].

Al-Baghdadi's theory of motion distinguished between velocity and acceleration and showed that force is proportional to acceleration rather than velocity. Abu'l-Barakat also developed Philoponus' theory of impetus, stating that the mover imparts a violent inclination (mayl qasri) on the moved and that this diminishes as the moving object distances itself from the mover.

Al-Baghdadi also suggested that motion is relative, writing that "there is motion only if the relative positions of the bodies in question change." He also stated that "each type of body has a characteristic velocity that reaches its maximum when its motion encounters no resistance." He also developed concepts which resemble several modern theories in physics.

All that we possess in the way of medical writing by Abu'l-Barakāt are a few prescriptions for remedies. These remain in manuscript and are as yet unstudied.

Legacy Abu'l-Barakāt's thought had an influence on some Islamic philosophers but little on Jewish thought. His works were not translated into Hebrew, and he is seldom cited in Jewish philosophy, probably because of his conversion to Islam. Ibn Taymiyyah heavily borrowed from the arguments of Ibn Malka and augmented them by propositions later made by Maimonides.

The famous theologian and philosopher Fakhr al-Din al-Razi was one of Abu'l-Barakāt's eminent disciples. The influence of Al-Baghdadi's views appears especially in Al-Razi's chief work Al-Mabāḥith al-Mashriqiyyah (Oriental Discourses). Abu'l-Barakāt influenced certain conceptions of Suhrawardi.