What is ijtihad?
Much of the study in the madrasah college centred on examining whether certain opinions of law were orthodox. This scholarly process of "determining orthodoxy began with a question which the Muslim layman, called in that capacity mustaftī, presented to a jurisconsult, called mufti, soliciting from him a response, called fatwa, a legal opinion (the religious law of Islam covers civil as well as religious matters). The mufti (professor of legal opinions) took this question, studied it, researched it intensively in the sacred scriptures, in order to find a solution to it. This process of scholarly research was called ijtihād, literally, the exertion of one's efforts to the utmost limit."
This new approach liberated scientific speculation from the dogmatic restraints of Aristotelian science, and paved the way for new approaches. Particularly within the field of theories of motion great advances were made, when such scholars as Jean Buridan, Nicole Oresme and the Oxford Calculators challenged the work of Aristotle. Buridan developed the theory of impetus as the cause of the motion of projectiles, which was an important step towards the modern concept of inertia. The works of these scholars anticipated the heliocentric worldview of Nicolaus Copernicus.