In the West, it probably traces back to Socrates; in the East, to Toyota: asking why five times will supposedly reveal the root cause of almost any problem.
Fresh out of design school, I enthusiastically tried this at a client meeting. Big mistake. By the third why, the room was so uncomfortable my account manager had to step in and save the day. My relationship with that client never recovered.
That meeting stuck with me. For years I puzzled over what went wrong, until it finally clicked: first, a 21-year-old repeatedly asking why is probably just weird; second, most people in business genuinely don’t know why they do what they do.
Since then, I’ve learned you should almost never directly ask anyone why. Definitely not five times in a row. It’s more effective to ask questions like “What do you do when X happens?” or “How do you feel when Y occurs?”. The real why usually emerges if you read between the lines.
There’s an asymmetry between the answers you seek and the questions you should ask.