Upon what principles is clean language based?
Clean Language attempts to enable our thinking (or more particularly the other person's thinking if viewed from the questioner's viewpoint) to be as pure and clear as possible so that clarity of awareness, understanding, decision-making and human relations is optimised.
The fundamental principles of Clean Language are quite simple:
Keep your opinions and advice to yourself as far as possible.
Ask Clean Language questions to explore a person's metaphors (or everyday statements).
Listen to the answers and then ask more Clean Language questions about what the other person has said.