The 5 Whys: Origins and Modern Applications

Author: Rob De La EspriellaBD3, CEO and Founder, BlueDragon IPS

Origins of The 5 Whys Technique

This blog will explain the origins of the 5 Whys method and explore misconceptions surrounding the 5 Whys technique. Most importantly, that it is a Socratic questioning technique and not a root cause analysis (RCA) methodology.

A Brief History of the 5 Whys

Socrates and the Socratic Method

The Socratic method is a teaching approach that relies on asking questions to stimulate critical thinking, challenge assumptions, and encourage active learning.  Socrates believed that by asking a series of probing questions, one could uncover the truth and challenge assumptions. His approach involved engaging in systematically questioning beliefs and ideas to stimulate critical thinking and arrive at a deeper understanding of the subject matter.

The 5 Whys Questioning Technique Comes from the Socratic Method

The Socratic method laid the foundation for the 5 Whys technique, a line of questioning to uncover the deeper causes of a problem. By repeatedly asking “why” a problem occurs, the 5 Whys help to move beyond superficial explanations and delve into the underlying factors.

Socratic questions go beyond mere information gathering; they challenge individuals to think critically, examine their assumptions, and consider alternative perspectives. Questions that seek clarification, probe evidence and reasoning, explore implications and consequences, and consider different viewpoints all contribute to a more comprehensive understanding of the problem.

By fostering a culture of Socratic questioning, organizations encourage their teams to engage in deeper, more meaningful discussions and analysis. As a result, the Socratic method has been widely adopted in various educational settings, particularly in law schools and other institutions of higher learning.

Here are some of the most prevalent users of the Socratic method:
  1. Law Schools: The Socratic method is indeed the foundation of teaching in many law schools, particularly in the United States. Harvard Law School, along with other prestigious institutions like Yale, Stanford, and Columbia, extensively use the Socratic method in their classrooms. Professors engage students in a dialogue, asking probing questions about legal cases, principles, and hypothetical scenarios to help them develop legal reasoning skills and a deep understanding of the law.
  2. Humanities and Social Sciences: The Socratic method is also employed in teaching philosophy, literature, history, and other humanities and social science subjects. Professors use questioning to encourage students to analyze texts, articulate their ideas, and engage in meaningful discussions.
  3. Medical Education: Some medical schools have adapted the Socratic method to help students develop clinical reasoning skills. By presenting medical cases and asking questions, instructors guide students through the process of diagnosis and treatment planning.
  4. Business Schools: Many business schools use case studies and Socratic questioning to help students develop problem-solving, decision-making, and leadership skills. The method encourages students to analyze real-world business scenarios, consider multiple perspectives, and articulate their thoughts effectively.
  5. Professional Development: The Socratic method is also used in various professional development settings, such as leadership training and executive coaching. By asking thought-provoking questions, trainers and coaches help individuals reflect on their experiences, challenge their assumptions, and develop new insights and strategies.

The Socratic method’s emphasis on critical thinking, active learning, and self-discovery has made it a valuable teaching approach across various disciplines and settings. Its widespread use in law schools and other notable institutions highlights its effectiveness in developing essential skills and fostering a deeper understanding of complex subjects.

The Toyota Production System

The 5 Whys as we know it today, is a fundamental tool in cause and effect analysis.  Its origins can be traced back to the 1930s at the Toyota Motor Corporation. Developed by Sakichi Toyoda, the founder of Toyota Industries, the 5 Whys approach was later refined and popularized by his son, Kiichiro Toyoda, and also Taiichi Ohno, who is considered the father of the Toyota Production System.

Sakichi Toyoda recognized the value of this iterative questioning process in identifying the root causes of manufacturing problems. He believed that by asking “why” five times, one could typically uncover the fundamental cause of an issue. The 5 Whys wasn’t just about fixing the immediate problem (i.e. the “symptom”); it was about preventing future occurrences. By understanding the deeper causes, Toyota could implement systemic changes to address the core issue and prevent similar breakdowns. This not only saved time and resources but also fostered a culture of ownership and responsibility among team members.

This relentless pursuit of “why” also fostered a culture of continuous improvement, a core tenet of the Toyota Production System (TPS) that emerged later, which emphasized the elimination of waste. Over time, the 5 Whys technique gained popularity beyond the manufacturing industry and has been adopted by various sectors, including healthcare, software development, and service industries. Its simplicity and effectiveness in identifying deeper-seated causes have made it a staple in problem-solving methodologies like Lean, Six Sigma, and Kaizen.

The 5 Whys Today

While originally used for identifying root causes in manufacturing, the 5 Whys transcended its origins. It became ingrained in Toyota’s problem-solving DNA and spread across various industries. Today, it’s a widely used technique in fields like quality assurance, engineering, and even customer service.

The 5 Whys is The Most Basic of Socratic Questioning Techniques

The 5 Whys technique, a fundamental tool in cause and effect analysis, is considered the most basic form of Socratic questioning. It should be noted that by itself, it is not a root cause analysis (RCA) methodology. There is a wide range of Socratic questioning techniques that can be employed to delve deeper into problems and uncover underlying issues.

Socratic follow-up questions differ from Lines of Inquiry questions in that they are used to thoroughly explore previous answers and arrive at the deepest-seated causes. Socratic questions aim to seek clarification, probe assumptions, examine various viewpoints and perspectives, and clarify implications and consequences.

The simplest way to formulate a Socratic question is by adding “WHY” to the answer to a line of inquiry question. (Lines of inquiry questions are developed from symptoms and are used to begin the cause and effect analysis).

Here are the most often used versions of the 5 Whys.

  • Add a WHY in front of the previous answer and continue to ask WHY when given the next answer.
  • Ask: and WHY is that? Can you elaborate some more?
  • Ask: WHY would you say this is happening?

However, in root cause analysis there are more sophisticated Socratic questions that may be used during cause and effect analysis to probe further:

1. Questions that seek clarification:

  • “What do you mean by [X]? Can you give us an example?”
  • “Is your basic point [X] or [Y]? Why do you say that?”
  • “How does relate to ? Could you explain that further?”
  • “Could you put that another way? Would you say more about that?”
  • “Is your basic point or ? Why do you say that?”
  • “What do you think is the main issue here?”

2. Questions that probe assumptions:

  • “Would a reasonable person make the same assumptions?”
  • “You seem to be making the assumption that [X], is that correct?”
  • “Why do you think your assumption holds up here? Is that always the case?”
  • “What allows you to assume that? What could we assume instead?”
  • “Why have you based your reasoning on _, rather than _?”
  • “Why do you think your assumption holds up here? Is that always the case?”

3. Questions that probe evidence and reasons:

  • “How do you know that is the case? Do you have evidence or first-hand knowledge of that?”
  • “Could you explain your reasons to us, and provide examples?”
  • “Why do you think that is true and what led you to that belief?”
  • “Why would you say that?”
  • “What other evidence do we need before we can agree on the facts?”
  • “Would a reasonable person doubt that evidence?”
  • “Can someone else provide corroborating evidence to support that answer?”
  • “By what reasoning did you come to that conclusion?”
  • “How could we find out whether that is true?

4. Questions about viewpoints or perspectives:

  • “You seem to be approaching this issue from [X] perspective. Is that correct?”
  • “Are there any other perspectives we should consider?”
  • “Would other groups/people respond the same? Why would they respond differently?”
  • “How would you answer the objections that __________ would make?”
  • “What might someone who believed differently say to that?”
  • “Could someone else see this issue another way? Who would it be and what would they say?”
  • “What would someone who disagrees with this viewpoint say?”
  • “What is an alternative viewpoint? It the other viewpoint well known or understood?

5. Questions that probe implications and consequences:

  • “What are you implying by that?”
  • “If this is the case, then what else must also be true?”
  • “What would the consequences be?”
  • “When you say __, are you implying that __ is the case?”
  • “If the implications are true, what consequences would they have?”
  • “If what you are implying is going on is actually happening, who else can corroborate it?”
  • “Would the consequences be certain or hypothetical?

Socratic questioning is a powerful tool for root cause analysis that extends beyond the basic 5 Whys questioning technique. By employing a variety of Socratic questioning techniques, investigators can gain a more comprehensive understanding of the problem and identify root causes more effectively. While the 5 Whys technique serves as a starting point, it is crucial to recognize the value of using a diverse set of questions to explore the issue at hand thoroughly.

Socratic questioning is an invaluable approach for conducting formal investigations or simply gaining a better understanding of a problem, ultimately leading to the discovery of effective solutions.

Using The 5 Whys in Modern Root Cause Analysis (RCA)

Clarifying the 5 Whys Terminology and Misconceptions:

Shifting From “5 Whys” to “Why Staircases”

The 5 Whys technique, when first introduced in the 1930s, was a groundbreaking approach that helped manufacturers identify and address the root causes of problems in their production processes. However, industries have evolved and become more complex. The “5” in 5 Whys is no longer a rigid rule, and it often takes many more Socratic questions to uncover the underlying issues in today’s intricate systems and processes.

Today, it is more practical to change the terminology to avoid stopping an investigation too soon (i.e. after 5 Whys).  There are other ways to describe the Socratic questioning technique, and here are some of the most common phrases.

  • Why Staircases
  • Why Sequences
  • Cause and Effect Sequences

Common Misconceptions About The 5 Whys

Many organizations across all industries consider the 5 Whys as a stand-alone root cause analysis methodology.  In reality, it is a technique for asking Socratic questions that help form the basis of a cause and effect analysis.  This misconception has led to organizations that use the 5 Whys as an approved RCA methodology.  Let’s clarify:

  • Asking Why 5 times constitutes a single line of inquiry.  This approach was originally useful in the 1930s in automobile manufacturing, but not useful in modern root cause analysis.
  • There is not enough rigor in a single 5 Why sequence (i.e., a single line of inquiry) to identify the root cause(s) with confidence.
  • The causes of complex or significant issues are not limited to a single root cause.  Using a single or a few 5 Why sequences can identify the deepest-seated causes of those lines of inquiry, but we cannot say with confidence that the deep-seated causes that are identified are in fact, root causes.
  • To identify the deepest-seated root causes of complex or significant issues takes a significant amount of rigor.  From experience, it takes 20 to 30 lines of inquiry (separate 5 Why sequences) to establish sufficient rigor so that we have confidence we have identified the root causes.
  • Another common misconception is that the questioning should stop at five iterations.  In practice, there is no set limit to the number of questions needed to uncover the root causes.  Investigators should continue asking “why” (or other Socratic questions) until they have thoroughly explored all relevant aspects of the problem.

RCA Tools That Use the Why Staircases Technique

As stated in the previous section, the 5 Whys it is not a stand-alone root cause analysis methodology but a basic questioning technique used for conducting cause and effect analysis.

Here is a list of RCA tools that use the “Why” questioning technique for conducting cause and effect analysis.

  1. Events and Causal Factors (ECF) Charts: ECF charts are a graphical representation of the sequence of events leading up to an incident or failure, along with the causal factors that contributed to each event. This tool helps investigators visualize the progression of the incident and identify the causal relationships between events and factors.
  2. Fishbone Diagrams (Ishikawa Diagram): The Fishbone Diagram, also known as the Ishikawa Diagram or Cause-and-Effect Diagram, is a visual tool that organizes potential causes of a problem into main categories, such as the 6 M’s (Machine, Method, Material, Man, Measurement, and Mother Nature) or the 4 P’s (Policies, Procedures, People, and Plant). This tool facilitates brainstorming and helps identify causes in a structured manner.
  3. Fault Tree Analysis (FTA): FTA is a deductive, top-down approach used primarily for equipment failures. It begins with a specific failure or incident and works backward to identify the contributing causes. The tool uses Boolean logic gates (e.g., AND, OR) to show the relationships between events and causes, helping investigators determine the most critical paths and root causes.
  4. Causal Loop Diagrams (CLD): CLDs are a systems thinking tool that illustrates the cause-and-effect relationships between variables in a system. They help identify reinforcing and balancing feedback loops, which can provide insights into the underlying dynamics of a problem and assist in identifying root causes.
  5. Cause and Effect Analysis: The process of conducting cause and effect can be called a tool. It simply requires a set of lines of inquiry questions to begin the analysis.

The Use of Why Staircases in Modern RCA

The Importance of Lines of Inquiry Questions To Kick Things Off

Developing great lines of inquiry questions is crucial in cause-and-effect analysis. They are the starting point for Why staircases (5 Whys).  The quality of our lines of inquiry questions directly impacts the depth and accuracy of the insights gained during the investigation. However, many RCA methodologies lack a disciplined approach to generating these questions that can lead us to the root causes.

As Albert Einstein once said, “If I had an hour to solve a problem and my life depended on the solution, I would spend the first 55 minutes determining the proper question to ask, for once I know the proper question, I could solve the problem in less than five minutes.” This emphasizes the importance of investing time and effort in crafting well-thought-out, focused questions that guide the analysis towards uncovering the true root causes of a problem.

What makes great lines of inquiry questions? Developing great lines of inquiry questions is a rigorous process that requires specific skills, a key element of the BlueDragon Integrated Problem-solving System (IPS).  Here are some of the basics.

  • Ask questions that are factual, based on evidence, and not based on hearsay or your own curiosity.
  • The questions should be focused on symptoms (i.e., deviations from requirements, non-conformance with specifications, etc.).
  • Ask neutral questions that avoid inserting any of your own biases (e.g., confirmatory bias; leading the witness).
  • Do not ask questions that are accusatory or seem to seek someone to blame.

The Importance of Rigor: How Many Why Staircases Are Needed?

Determining whether our investigation has the sufficient level of rigor to allow us to conclude that we have identified the root causes of a problem is a subjective call.  Here are some industry guidelines from the Nuclear Power/Energy sector:

  • Simple issues of low consequence and complexity: Rapid investigations can be conducted using less than 10 lines of inquiry / cause and effect sequences (Why staircases).  The deepest-seated causes identified using this low number of Why sequences are not root causes, simply the deepest-seated causes.
  • Issues of moderate consequence and complexity: These are the types of issues where management has decided they can tolerate a repeat event, and a full RCA is not required.  Apparent Cause Evaluations (ACE) can be conducted using 10 to 30 llines of inquiry / cause and effect sequences (Why staircases).  The deepest-seated causes identified using this relatively low number of Why sequences are called “Apparent Causes.”
  • Issues of high consequence and complexity: These are the types of issues that management has decided it cannot tolerate a repeat event, and a full RCA is required.   RCA investigations require the highest level of rigor and should be conducted using more than 30 lines of inquiry / cause and effect sequences (Why staircases).  The deepest-seated causes identified using this rigorous approach can be “Root Causes.”

Socratic Questions Remain the Foundation for RCA and Continuous Improvement

Socratic questioning lies at the heart of effective root cause analysis (RCA) and continuous improvement efforts. By employing a systematic approach to questioning, organizations can delve deeper into problems, uncover hidden assumptions, and reveal the underlying causes of failures or inefficiencies. The 5 Whys technique, the most basic form of Socratic questioning, serves as a starting point for cause and effect analysis, but it is essential to recognize that the “5” is not a rigid limit. In today’s complex systems and processes, it often takes a diverse set of Socratic questions to thoroughly explore the problem at hand and arrive at the root causes.

Moreover, Socratic questioning is not limited to reactive problem-solving; it is also a powerful tool for proactive continuous improvement. By regularly questioning processes, procedures, and practices, organizations can identify potential weaknesses, inefficiencies, or areas for enhancement before they lead to significant issues. This proactive approach to questioning enables organizations to stay ahead of problems and continuously refine their operations.

Integrating Socratic questioning into various root cause analysis tools, such as Events and Causal Factors (ECF) Charts, Fishbone Diagrams, and Fault Tree Analysis, further enhances their effectiveness. By combining structured cause-and-effect analysis with the power of Socratic questioning, organizations can develop a robust, multi-faceted approach to problem-solving and continuous improvement.


It’s time to modernize the 5-Whys technique and recognize its true role in root cause analysis (RCA). Developed in the 1930s for manufacturing, the 5-Whys has been widely adopted but often misunderstood. As industries have evolved and become more complex, the limitations of relying solely on the 5-Whys have become apparent.

BlueDragon IPS emphasizes that the 5-Whys is not a complete RCA methodology but rather a Socratic questioning technique used to support cause-and-effect analysis. The “5” is not a magic number; it often takes many more targeted questions to uncover the root causes in today’s intricate systems and processes. Unfortunately, misconceptions about the 5-Whys have led some organizations to use a few simplistic 5-Why sequences as the basis for their RCA efforts. This approach may suffice for the simplest issues but fails to provide credible results for more complex and significant problems. Relying solely on the 5-Whys can lead to superficial analysis, overlooking critical factors and relationships.

By understanding the true role of the 5-Whys and integrating Socratic questioning into a robust RCA methodology, organizations can enhance their problem-solving capabilities. BlueDragon IPS equips participants with the skills and knowledge needed to conduct credible, evidence-based RCA that uncovers the true root causes of complex issues.

In conclusion, modernizing the 5-Whys involves recognizing its limitations and embracing a more comprehensive approach to RCA. BlueDragon IPS training helps clarify misconceptions and demonstrates how Socratic questioning, combined with structured cause-and-effect analysis tools, enables organizations to solve problems effectively in today’s complex world. By adopting these best practices, organizations can drive continuous improvement, prevent recurring issues, and achieve lasting success.


About the Author:

Rob De La EspriellaBD3, CEO and Founder, BlueDragon IPS

Deming Prize winning team member and pioneering Nuclear Quality Assurance expert Rob De La Espriella draws from four decades of experience in the commercial nuclear power sector and the nuclear weapons complex to offer deep insights into Root Cause Analysis and Total Quality Management. Rob is a leading expert in solving complex human-centric problems in our modern work environments, and has re-defined how organizations solve complex problems with the BlueDragon Integrated Problem-solving System (IPS), the first universal problem-solving system that can be applied to all regulated industries.  Rob is a former Navy nuclear submarine officer, a decorated Resident Inspector with the US Nuclear Regulatory Commission, and a senior manager at nuclear plants.  In 2023, he was accepted into the Forbes Business Council as a Forbes contributor.

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