John Duns Scotus

John Duns Scotus was a Scottish Franciscan friar and scholastic philosopher known for his subtle and rigorous argumentation, which earned him the medieval title Doctor Subtilis. He developed original positions in metaphysics, epistemology, and ethics that challenged both Aquinas and Ockham. His concept of haecceity — the "thisness" that makes an individual thing the particular thing it is — and his defence of the Immaculate Conception were among his most lasting contributions.