Philosophy
The Problem of Universals in Medieval Philosophy and Nominalism
Quick fact
The debate over universals was so intense that it led to the nominalist William of Ockham being accused of heresy, and his views were condemned by the Pope in 1324.
Why this is interesting
You've seen many red apples, red cars, and red roses—but have you ever seen 'redness' itself? Medieval philosophers argued for centuries about whether such shared qualities are real things or just names we invent.