John Duns Scotus

Theologian

John Duns Scotus was a medieval Christian theologian and philosopher remembered mostly for his defense of the doctrine of Immaculate Conception (that is, that Mary, the mother of Jesus, was free of sin). A member of the Franciscan Order, Scotus taught in Oxford, Paris and Cologne (where he died), embraced Aristotelian philosophy and founded the branch of Scholasticism later called Scotism, a critical response to the teachings of Thomas Aquinas. Called Doctor Subtillis ("The Subtle Doctor"), Scotus upheld the notion of the separate nature of a rational and independent soul, modified the ontological argument put forth by Anselm and defended the primacy of divine will over intellect. Scotus was beatified by Pope John Paul II in 1993.

Extra credit: Scotus followers were called Scotists and "duncemen" (after his middle name). Their strong opposition to the revival of classical studies during the Renaissance led to use of the word "dunce" to mean an uneducated person or a numbskull.