Who was he? A high (late) middle ages philosopher and theologian, who was referred to as “the subtle doctor.” He may have been born in Scotland (in Duns) and certainly studied in France and likely lectured at both Oxford and Cambridge. Little is known about him personally, though he was born around 1266 and died in 1308. He is also the apparent founder of scholasticism as a school of thought (something Martin Luther liked to mock).
Why was he important? John Duns Scotus pioneered rigorous philosophical thought in the West before it was a thing. He followed largely the thought of Aristotle (as became common among Scholastics) and developed Aristotle’s ideas further. In particular, Scotus reinvigorated the idea of formal distinctions and univocity of being. While these are very complex terms, for the sake of ease, they are ways in which we can talk about and discuss God as being in himself and as Trinity, as well as other metaphysical things. Further he emphasized both human freedom and divine will through developing the Aristotelian concept of contingency to its current usage. In this way, Scotus may have indirectly influenced the way science is done and the language used to describe scientific methodology. For Roman Catholics, he also developed the idea of the immaculate conception of Mary. While I don’t personally believe in such an event, if one has a very strong view of both Original Sin (and Guilt) coupled with baptismal regeneration of infants, as the Roman Catholic Church does, it seems all but required that some account of the sinlessness of Mary be made because of the sinlessness of Christ (however, it seems this might lead to a infinite regress). Despite my personal dislike of this, it is part of Duns Scotus’s heritage.
Fun Fact: John Duns Scotus’s name is the source of the word “dunce,” which was a title given to someone in school in the US who had either not completed assignments, or had made some other major failure. The “dunce cap” that the child was made to wear is modeled after the hat Duns Scotus is seen wearing in the above picture.
Where might I have heard of him? The reason for this negative association is because of the Protestant Reformation, but Martin Luther in particular. Luther sought to deride the predominant Roman Catholic Theology of the day and so targeted he Scholastics, whom he referred often as “some learnèd men”. He sought to ridicule their focus on speculative philosophy that went beyond biblical interpretation (not realizing that he himself often did the same) and so suggested that they argued about “how many angels can dance upon the head of a pin” which is not something the Scholastics were ever seriously concerned with. It was more rhetorical than factual, unfortunately next to Aquinas, Duns Scotus’s reputation seems to have been hit the worst. The reason “dunce” was so popular in the US is likely due to our Puritan heritage.