Most dukes, kings, emperors, and the like employ a Fool who is allowed to question and even mock the lord's words and ideas. The Fool provides a useful filter and counter-balance which may occasionally dissuade the lord from some disastrous mistake.
Philosophers and such seekers of wisdom can rarely afford a Fool at Guild rates and often just find an ordinary fool to hang around with. It is often said that a fool can ask more questions than a wise man can answer. Therefore, if the wise man manages to answer all the fool's stupid questions about some new idea, he may feel that he's really on to something.
Wen the Eternally Surprised, in his youth, employed an ordinary fool named Clodpool and had to explain to him his revelation that the universe is re-created every instant and the world of memory doesn't exist. On this morning, Clodpool asked what the master wanted for breakfast; with a little thought, Wen managed to answer this and a Philosophy was born.