Many people would be surprised to be told that there were any great medieval thinkers. If a great thinker is one from whom we can learn today, and if “medieval” serves as an adjective for describing anything which existed from (roughly) the years 600 to 1500 ad, then, so it is often supposed, medieval thinkers cannot be called “great.”
Why not? One answer often given appeals to ways in which medieval authors with a taste for argument and speculation tend to invoke “authorities,” especially religious ones. Such invocation of authority is not the stuff of which great thought is made—so it is commonly said today. It is also sometimes said that greatness is not to be found in the thinking of those who lived before the rise of modern science, not to mention that of modern philosophy and theology. Students of science are nowadays hardly ever referred to literature earlier than the seventeenth century. Contemporary students of philosophy in the twentieth century are often taught nothing about the history of ideas between Aristotle (384–322 bc) and Descartes (1596–1650). Modern students of theology have been frequently encouraged to believe that sound theological thinking is a product of the nineteenth century.
Yet the origins of modern science lie in the conviction that the world is open to rational investigation and is orderly rather than chaotic—a conviction which came fully to birth, and was systematically explored and developed, during the Middle Ages. And it is in medieval thinking that we find some of the most sophisticated and rigorous philosophical and