Any philosophy student should be familiar with Aristotle’s “Organon,” but the ancient Greek philosopher didn’t call it that himself. The “Organon” is a collection of six of Aristotle’s fundamental writings on logic, compiled and named as such by his 15th-century followers. The word “organon” comes from Greek, and literally means “instrument, organ.” Even when not referring directly to Aristotle’s logic, an organon can be any framework of reasoning or a tool used to guide thought.