Updated 28-Jun-2024
Sakichi Toyoda and the Five Whys
Sakichi Toyoda, the founder of Toyota Motor Company, is considered one of the greatest if not the greatest inventor of Japan and the father of Japanese Industrialization. His impact on the world should not be underestimated. As with most historical figures, our tasks are different because we live in a different world. However we can learn from the thinking of this great man.
Toyoda invented the Five Whys question asking method for discovering the root cause of events, particularly failure. The idea is to get at root causes rather than symptoms so that improvements rather than merely temporary fixes can be made to a system.
Root Cause Discovery is Difficult
Getting at root causes is not easy, and the method is not foolproof, but it is a profound and useful tool. Root cause analysis is a fundamental feature of innovative systems otherwise the changes to the system will be cosmetic, or worse will cause the system to further degrade.
Example of Root Cause 5 Whys Analysis
My car will not start. (the problem)
- Why? - The battery is dead. (first why)
- Why? - The alternator is not functioning. (second why)
- Why? - The alternator belt has broken. (third why)
- Why? - The alternator belt was well beyond its useful service life and has never been replaced. (fourth why)
- Why? - I have not been maintaining my car according to the recommended service schedule. (fifth why, a root cause)
Understanding and the Five Whys
It is important to also ask the five whys, not only in events of failure in terms of production, but failure in terms of a clash of understandings and in disagreements. Why do we disagree? What is the failure of perception or the failure of conception taking place? Understanding root causes is key to communication and product development processes as well as engineering quality control.