Recently I met with some Lean practitioners and we spent some time discussing the use of the Five Whys questioning technique for discovering to a root cause or underlying reason. It is a form of laddering interview technique.

The idea is derived from six types of Socratic questions [Paul and Elder] that: (i) clarify thinking, (ii) challenge assumptions, (ii) probe reasons and evidence, (iv) examine alternative viewpoints and perspectives, (v) examine implications and consequences and, also, (vi) ask questions about the question.