Ali Al-Qushji was an Islamic scientist during the 15th century, most interested in the fields of mathematics and astronomy. He wrote his findings in several books, many of which outlined his novel work in a variety of different scientific contexts. In perhaps his most important astronomical work Concerning the Supposed Dependence of Astronomy upon Philosophy, Qushji proposed a system of astronomy that rejected Aristotelian physics. Qushji proposed that an astronomer did not need a philosopher's ideas in order to establish physical principles of the natural world This assertion separated philosophy and astronomy, allowing astronomy to become a much more empirically based science. His work marked an important step away from Aristotelian physics and towards independent physics, considered to be a significant ideological shift in science.
In so doing, Qushji questioned concepts that had very little or incomplete empirical backing. Many scientific ideas were based off of Aristotelian physics, which he rejected for a more scientific approach to observations. For example, Qushji contended that there was no reason to believe that heavenly bodies moved in uniform circular motions simply because it fell in line with Aristotle’s conception of physics. Furthermore, Qushji explored new claims based off of observations and evidence, perhaps the most significant regarding the theory of Earth’s movement. Whereas Ptolemy “proved” that the Earth was immobile, Qushji suggested that this statement was false. He explored the idea of a moving Earth and found mathematical evidence for the Earth’s rotation through the observation of comets, concluding that the Ptolemy’s ideas may not have been true. Beyond this, Qushji’s books detailed the multitude of observations he made about climate, orbits, stars, arithmetic and more.
As a member of the Ottoman State, Qushji understood the importance of science in society, particular mathematics, medicine, and astronomy. He began as a student of Ulugh Beg, who founded The Samarqand Observatory. Having access to this institution, Qushji was able to utilize one of the most important observatories from the 15th century to inform his discoveries, eventually becoming the director of the observatory. During this period, Qushji produced an enormous catalogue of the stars and discussed the distances between the celestial bodies. In addition, the 15th century was a period of great growth in the cultivation of learning throughout Islamic states. Qushji was hired by the Ottoman ruler, establishing his own school and educating other scholars, continuing a system of encouraging learning that had paved the way for him to succeed in academia.