- Aristotle lived from 384 BC to 322 BC in Macedonia and was a student of Plato, though he disagreed with some of Plato's teachings.
- Aristotle developed his own theory of universals, believing that universals exist only instantiated in individual objects, rather than as abstract forms.
- In contrast to Plato, who was a rationalist believing knowledge comes from reason, Aristotle was an empiricist who believed all knowledge comes from experience sensed through the world.