Lately I’ve been involved in several conversations of “Is lean about tools or is it about principles?” Hardly anybody argues for the tools. The popular consensus is that Lean is about principles, but it is a vague and loose consensus at best.
What do we mean by principles?
One definition of principle is a fundamental truth or proposition that serves as the basis for a system of belief, behavior or a chain of reasoning. The principles of a religion, of good parenting, or being a successful supervisor, are examples. Principles are also assumptions, theories, or ideas we accept as being true and act accordingly. We also say that someone who is “principled” or is a man or woman “of principle” when they behave in according to a set of beliefs, ethical code, or standards. Yet another definition of principle is that of scientific theories and explanations of natural phenomena.
When we say “Lean is about principles” are we speaking about a set of fundamental truths that we believe to be true, a personal code of moral and ethical conduct, scientific explanations for phenomena in our universe, or all of the above? Lean is built on principles that govern how we think. Lean principles are meant to guide our behavior. And yes, Lean systems are built up from scientific principles that explain how things work, and have worked long before Toyota, Deming or Ford put those principles to use.
Liker’s 14 Toyota Way Principles
The so-called Lean principles handed down to us are often an unruly mix of the above. Often they are not stated as true principles, but as guidelines, precepts or directives to use tools or practice Lean methods. Taking an account of Jeffrey Liker’s 14 principles from his book The Toyota Way, we can see that 13 of them are precepts and one of them (#6) is a belief presented a principle. Unlike scientific principles, none of these provide a causal chain to explain phenomena in the world.
- Base your management decisions on a long-term philosophy, even at the expense of short-term financial goals.
- Create a continuous process flow to bring problems to the surface.
- Use ‘pull’ systems to avoid overproduction.
- Level out the workload (work like the tortoise, not the hare).
- Build a culture of stopping to fix problems, to get quality right the first time.
- Standardized tasks and processes are the foundation for continuous improvement and employee empowerment.
- Use visual controls so no problems are hidden.
- Use only reliable, thoroughly tested technology that serves your people and process.
- Grow leaders who thoroughly understand the work, live the philosophy, and teach it to others.
- Develop exceptional people and teams who follow your company’s philosophy.
- Respect your extended network of partners and suppliers by challenging them and helping them improve.
- Go and see for yourself to thoroughly understand the situation.
- Make decisions slowly by consensus, thoroughly considering all options; implement decisions rapidly.
- Become a learning organization through relentless reflection and continuous improvement.
Precept #1 is based on a belief in a fundamental truth that working towards long-term prosperity has a better chance of delivering it long-term, while working for only short-term financial gain is unlikely to secure the long-term. We could restate #3 as a scientific principle to explain that pull systems reduce inventory, lead-times and cost by allowing consumption signals to trigger production, reducing the gap in time between demand and supply. Wordy, but now we have something closer to a scientific principle. Number 5 could be a principle of conduct, stated that it is better to expose problems and not hide them so that we can address them before they grow worse and more costly.
Restated as a principle, #7 “Use visual controls so no problems are hidden” would be “In order to solve problems it is necessary to expose them” or “The sooner we find a problem the sooner we can begin solving it”. A Lean principle would not specify “visual controls” but merely that it is desirable to expose problems. Vision happens to be a human’s most effective sense for sensing differences. As a fundamental principle not bound to vision, the method to expose problems could be visual, audial, tactile, olfactory, or in another way that we haven’t yet invented. This may seem ridiculous. But today there are dogs trained to detect the smell of cancer in people. Someday soon we may have non-visual controls to exposing our medical problems, following the spirit of #7.
It takes some work but can identify the principles behind the 14 points above and restate them as such.
The 5 Lean Principles, the 4 Rules of Toyota DNA
Similarly, the five Lean principles of the Lean Enterprise Institute are presented not as fundamental truths, moral codes or scientific theories with explanatory power but as directives. To be Lean, we are advised to reach into our tool bag and identify value, map value streams, create flow, establish pull and seek perfection.
The paper Decoding the DNA of the Toyota Production System by Bowen & Spear offers a set of design principles for a Lean management system in the form of the four rules, part of the tacit knowledge of how work is done at Toyota.
- All work must be specified according to content, sequence, timing and outcome
- Every connection in the process must be direct with a binary yes/no responses
- Every service process must flow along a simple, specified path
- Improvement must be done based on the scientific method, under the guidance of a coach, and by those who do the work closest to the problem
The rules explain the beliefs that underly the visible competencies at Toyota, but do not explain how these are underpinned by practical, moral or scientific truths. Presumably explanation is not necessary since they are taught to people tacitly, not explicitly. They were taught not as rules or principles, but learned through rote repetition and the practice of tools. It is only possible to infer these rules because of the plethora of visible artifacts and tools (#1 standard work, #2 various visual OK / NOK signals, #3 one piece flow, #4 QC circles, suggestion systems, etc.). It seems unlikely that the authors intended the reader to build their Lean management system based on these four rules.
Can we really say Lean is about principles when our best-published authorities present principles to us that are essentially directives to use tools?
Lean Transformation Model worded as principles
The LEI’s Lean Transformation Model steers clear of Lean tools and comes closest to being a set of Lean principles. The five elements of the model can be worded as principles, such as
1) leadership is responsible for building the management system,
2) Lean transformation is driven by basic thinking, mindset and assumptions,
3) Lean follows a situational approach of solving problems,
4) Problems are solved through practical changes to how things are done, and
5) sustainable improvement requires developing everyone’s capabilities.
The importance of solving problems towards a True North or value-driven purpose can either be packed into principle 3, or stated as a separate principle. In contrast to other attempts at Lean principles, this model feels like a set of gentle suggestions.
Where Toyota puts their principles
Taiichi Ohno did not embark upon his journey of discovery and development of the Toyota Production System with a set of Lean principles. For him, the “Lean journey” was a highly pragmatic affair. The fundamental truth that drove Ohno was, “Making things at lower cost will lead to prosperity” and “Higher productivity leads to lower cost” and “Removing waste from work leads to higher productivity” and “When improving, money is limited but creativity is not.” These were in contrast to the prevailing beliefs or principles such as “We’ll make it up in volume” or “We can add a profit margin onto our cost to set selling price” or “Newer, faster machines will reduce cost.” Taiichi Ohno flipped these notions on their heads, proving that we can make cheaper by making less, that older and simpler machines could be employed profitably, everyday people also have great ideas, and that profit comes when the market sets the price and we reduce our costs. We could call these Lean principles.
The Toyota Management Vision is presented as a tree, using the metaphor natural phenomena to explain how sustainable growth is achieved. At the root are Toyota’s values, precepts, principles, and the Toyota Way which houses what we call the Lean tools. There is a lot packed into this diagram, much of it tacit knowledge that is reinforced through teaching and practice daily. Perhaps the best thing about this image is that it places principles, precepts and tools at the root the trunk, with the fruits of the tree providing the reasons guided by the roots. Not enough diagrams of Lean roadmaps or lists of principles do this.
Is Lean about tools or is it about principles?
If Lean is all about principles, where is the consensus list of Lean principles? Why are we satisfied with precepts to practice Lean methods and tools? The tools derive from fundamental truths, morals and scientific principles, while the principles are put into practice by employing tools. Perhaps we need to ask better questions.