Kalam

Taqi al-Din Ahmad ibn Taymiyyah (1263–1328 CE) was a Hanbali jurist and theologian in Mamluk Damascus and Cairo. He critiqued speculative theology and practices such as tomb visitation, issued influential fatwas, and was imprisoned repeatedly. His writings shaped later Islamic reform movements.

The Mu'tazilite school of Islamic theology gives priority to reason in interpreting matters of belief. It emerged in Basra in the early eighth century, was the official doctrine of the Abbasid state under al-Ma'mun and his two successors, and set out its theology under five principles.

Nasir al-Din al-Tusi (1201-1274) was a mathematician, astronomer, philosopher and theologian who directed the Maragha observatory under the Ilkhanids, made trigonometry a discipline in its own right, and devised the geometrical device known as the Tusi couple.