1266 – 1308
John Duns Scotus (c. 1266–1308) was a Scottish Franciscan friar and one of the most influential scholastic philosophers and theologians of the High Middle Ages, known as the 'Subtle Doctor' for the precision of his argumentation. He made foundational contributions to metaphysics, epistemology, and natural theology, most notably his doctrines of the univocity of being and haecceity. His work shaped both medieval Scholasticism and early modern philosophy through the Scotist school.
Developed the doctrine of the univocity of being, arguing that 'being' is predicated in the same sense of God and creatures
Introduced haecceity ('thisness') as the principle of individuation distinguishing particular entities
Formulated sophisticated cosmological and modal arguments for the existence of a first efficient cause
Defended the Immaculate Conception of Mary on theological and philosophical grounds, influencing later Catholic doctrine
Advanced a voluntarist account of divine and human freedom that influenced subsequent ethics and theology