Why the 5 whys

Today, I will talk about a simple and powerful tool, the 5 whys. This method can be used to solve all kinds of problems and finally find the source of your problems.

When a problem arises, we often ask ourselves the question, “who made the mistake? “. We should rather ask the question, “why did this happen? “. The purpose of lean thinking is not to find a culprit, but to identify the problem at the source and fix it so that the problem does not reoccur.

The 5 whys go further than answering the question, “why did this happen?” Once the cause has been identified to the first why, the question is asked why, again and again, in order to find the original cause. We call the method the 5 whys, but you can ask why until you get to the source of the problem.

I recommend you use this tool in a participatory way with your work teams. By involving them, you will mobilize them and you will start implementing a culture of continuous improvement.

To understand the problem, do not forget to go to the place where the problem is (the famous Gemba). If you use the 5 whys in your office, it will not be effective.


Here’s an example:

  • Why did the employee fall?
  • Because there was oil on the floor


  • Why was there oil on the ground?
  • The hose behind the equipment was leaking.


  • Why has preventive maintenance not been done?
  • Because we do not do preventive maintenance, we wait until the equipment breaks to repair it.


By not asking enough whys, we can put in place actions that will not solve the problem at the source. Your problems will come back and you will wonder why because you already did a corrective action. I must not have been the right action because you didn’t find the true source of your problem.

So if your problems come back, ask yourself why! It is by going to the source that we can insure performance!

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