1266 – 1308
John Duns Scotus (c. 1266–1308) was a Scottish Franciscan friar, philosopher, and theologian whose subtle and rigorous thought earned him the title 'Doctor Subtilis.' He made groundbreaking contributions to metaphysics, theology, and the theory of free will, developing influential accounts of univocity of being, haecceity (individual essence), and the primacy of the will.
Developed the doctrine of the univocity of being, arguing 'being' is predicated in the same sense of God and creatures
Introduced haecceity (thisness) as the principle of individuation
Formulated influential arguments for the existence of God based on the concept of an infinite being
Advanced a voluntarist ethics emphasizing the primacy of the will over the intellect
Provided a sophisticated defense of the Immaculate Conception that influenced later Catholic doctrine