
ByBryan Collins, Former Contributor.
March 10, 2025
Taiichi Ohno had a mission.
As a diligent production engineer at Toyota during the 1940s and 1950s, he wanted to eliminate waste and inefficiency in the company's production processes.
After the war, like many at Toyota, Ohno understood the company had to catch up with American companies...or else.
He also knew firsthand how many components Toyota stockpiled for its production line at great expense.
After earning a promotion, Ohno adopted an innovative approach to Toyota's stockpiling problem and asked senior management why the company adhered to such a costly solution.

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Not satisfied with their answers, Ohno continued asking, “Why?”
He persevered until he got to the root of why the company believed it needed large stockpiles.
Ohno also questioned why Toyota needed to buy specialized, expensive and difficult to customise machines when general purpose, smaller machines were less expensive, could produce a wider variety of parts and were easily reconfigured.
Enter The Five Whys
Ohno developed his method of interrogative questioning into a problem-solving tool known as the Five Whys.
Ohno used the example of a machine that stopped functioning to teach his method of problem-solving to employees:
Why did the machine stop?
There was an overload,and the fuse blew.
Why was there an overload?
The bearing was not sufficiently lubricated.
Why was it not lubricated sufficiently?
The lubrication pump was not pumping sufficiently.
Why was it not pumping sufficiently?
The shaft of the pump was worn and rattling.
Why was the shaft worn out?
There was no strainer attached, and metal scrap got in.
In this case, engineers could see the root issue wasn't mechanical, i.e., a faulty fuse. Instead, they could attribute the cause to human error, i.e., someone should have attached a strainer.
They can use this insight to put a process in place that mitigates human error.
How To Use The Five Whys
Today, Ohno is known as father of Toyota's modern production system and of lean manufacturing. The company says he "built the foundation for the Toyota spirit of "making things."
Whether you make things or otherwise, Ohno's classic problem-solving tool is useful for business people in all kinds of roles.
In The Lean Startup, Eric Reis explained, “By asking and answering ‘why’ five times, we can get to the real reason for the problem, which is often hidden behind more obvious symptoms.” Asking “why” five times can help you uncover problems and address their underlying causes.
For example, let's say you're running a coaching business and your monthly revenue recently dropped. Ask:
Why are my business revenues down?
Because several of my coaching clients ended their contracts.
Why did they end their contracts?
They'd reached the natural end of their coaching programs, and I didn't find new clients in time.
Why didn't you find new clients in time?
I was spending all my free time coaching these clients rather than on business development.
Why were you spending all your time coaching these clients?
Coaching takes up a huge part of my working day, and I normally have administrative tasks to attend to after each call.
Why do you have to spend time on administration?
Because I haven't outsourced this part of my business yet.
In this case, our struggling coach could use a site like Upwork to hire a virtual assistant and then use the freed hours to find new coaching clients.
Solve A Problem Today
If you work for yourself, you could answer the five whys in a journal. Alternatively, if you work as part of a team, ask these questions at the next review or company offsite.
Most people don’t like asking difficult questions because they’re afraid of the answers. They might have to quit a job they hate, abandon a supposedly innovative idea or even start a difficult conversation with a colleague or peer.
Take heart from Ohno. He said, "Having no problems is the biggest problem of all.”
Like with a premortem, asking the five whys can help you find success—just like Toyota.
ByBryan Collins, Former Contributor.
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