What is the "5 Why" technique, and how does it work?
Ask "why?" about a problem roughly five times in a row — each answer becomes the next question — to drill past the symptom down to the real root cause.
5 Why is a root-cause technique: you start from the visible problem and keep asking why it happens, feeding each answer into the next "why", until you reach a cause you can actually act on (usually after about five steps — "five" is a rule of thumb, not a magic number).
A worked example — a machine stopped working:
- Why did the machine stop? A fuse blew from an overload.
- Why the overload? The bearing wasn't lubricated enough.
- Why insufficient lubrication? The oil pump wasn't pumping enough.
- Why? The pump's intake was clogged with metal shavings.
- Why? There was no filter on the intake.
The surface fix is "replace the fuse"; the root fix the five whys reveal is "fit an intake filter". Stopping at the first answer treats symptoms forever; pushing through to the root fixes the problem for good.
Tip: It works socially too — have someone else ask you the whys. Being forced to justify each answer exposes the assumptions you'd skip past on your own.