In Reply to Parent Post by Jim Wynne
I always wondered about the 5-why thing. If a person isn't smart enough to know when he's found the answer (and must be prompted to keep asking "why?"), how can he be smart enough to know when to stop at all? It doesn't make sense on any level.
I agree with you Jim.
Taiichi Ohno (architect of TPS), described the 5-whys method as "the basis of Toyota's scientific approach . . . by repeating why five times, the nature of the problem as well as its solution becomes clear." This method of root-cause-analysis went beyond Toyota and spread over the world. Taichi Ohno felt that five iterations of 'why' would suffice to surface any problem, and it became a rule of thumb. But in TPS (Toyota Production System) too, asking 'whys' was not restricted to five times. Despite going beyond 'five times' at times, this method continued to carry the original title '5-why'.
Later, someone (perhaps Peter Scholtes) started using the '5-why' analysis under the name of 'why-why' analysis, and today both the nomenclatures are concurrently in use.