John Duns, commonly called Duns Scotus (/ˈdʌnz ˈskoʊtəs, ˈskɒtəs/; c. 1266 – 8 November 1308), is generally considered to be one of the three most important philosopher-theologians of the High Middle Ages. Scotus has had considerable influence on both Catholic and secular thought. The doctrines for which he is best known are the "univocity of being," that existence is the most abstract concept we have, applicable to everything that exists; the formal distinction, a way of distinguishing between different aspects of the same thing; and the idea of haecceity, the property supposed to be in each individual thing that makes it an individual. Scotus also developed a complex argument for the existence of God, and argued for the Immaculate Conception of Mary. Duns Scotus was given the scholastic accolade Doctor Subtilis (Subtle Doctor) for his penetrating and subtle manner of thought. He was beatified by Pope John Paul II in 1993.
Little is known of Duns Scotus apart from his work. His date of birth is thought to have been between 23 December 1265 and 17 March 1266, born into a leading family of the region. The site of his birth, in front of the Pavilion Lodge, near the North Lodge of Duns Castle, is now marked by a cairn which was erected in 1966 by the Franciscan friars of the United Kingdom to mark the 700th anniversary of his birth. Duns Scotus received the religious habit of the Friars Minor at Dumfries, where his uncle, Elias Duns, was guardian.