During my short time at Toyota, I learned this lesson well: we were always encouraged to “try and see” — which meant that we should try new ways of doing things to see if they “worked.” At bottom, Lean is quite pragmatic — not axiomatic.
Practice, not theory. This theme has come up a number of times in my study of the Toyota Production System. It’s worth reflecting on this idea. In 1973 Taiichi Ohno titled the foreword to the first textbook on the Toyota Production System “Practice, Not Theory” （論より実践）. He concludes the foreword by saying:
“If you are going to do TPS you must do it all the way. You also need to change the way you think. You also need to change how you look at things.
Just as magicians have their tricks, the gemba technique has its tricks. The magician’s trick in this case is “the relentless elimination of waste”. In order to eliminate waste, you must develop eyes to see waste, and think of how you can eliminate the wastes you see. And we must repeat this process.
Forever and ever, neither tiring nor ceasing.”
A decade later, in the foreword to Yasuhiro Monden’s book Toyota Production System published in 1983 by the Institute of Industrial Engineers, Taiichi Ohno states:
“…since the Toyota production system has been created from actual practices in the factories of Toyota, it has a strong feature of emphasizing practical effects, and actual practice and implementation over theoretical analysis. As a result, it was our observation that even in Japan it was difficult for the people of outside companies to understand our system; still less was it possible fo the foreign people to understand it.
This time, however, Professor Monden wrote this book by making good use of his research and teaching experience in the United States. Therefore, we are very interested in how Professor Monden has “theorized” our practice from his academic standpoint and how he has explained it to the foreign people. At the same time, we wish to read and study this book for our own future progress.”
Ohno also wrote in this foreword “Although we have a slight doubt whether our Just-in-time system could be applied to the foreign countries…” due to differences in social and cultural factors, he stated “…we hope and expect that another effective American production system will be created utilizing this book for reference.”
To Ohno TPS was not a theory that could be applied readily in other countries, but rather a collection of practices developed through trial and error at Toyota. Ohno passed away before ever visiting Toyota Motor Manufacturing Kentucky (TMMK) or any of Toyota’s factories in the United States. One wonders whether his hope that we create “another effective American production system” has yet been realized?
Here in the United States, former Toyota Chairman Fujio Cho, one of Taiichi Ohno’s brightest students and the executive responsible for successfully launching TMMK, said:
“We place the highest value on actual implementation and taking action. There are many things one doesn’t understand and therefore, we ask them why don’t you just go ahead and take action; try to do something? You realize how little you know and you face your own failures and you simply can correct those failures and redo it again and at the second trial you realize another mistake or another thing you didn’t like so you can redo it once again. So by constant improvement, or, should I say, the improvement based on action, one can rise to the higher level of practice and knowledge.”
Cho learned Ohno’s lesson well. But why did Ohno feel so strongly the need to state “practice, not theory”? This may have been due in part to what Professor Satoshi Hino refers to as “An Emphasis on Theory” at Toyota, in chapter 2 of his book Inside the Mind of Toyota: Management Principles for Enduring Growth. Hino writes that Toyota’s leaders including Eiji Toyoda, Shoichiro Toyoda, Hiroshi Okuda and Fujio Cho,
“…all advocated the theory of an annual production of 200,000 to 300,000 of their basic models, which constitutes the economic production unit, the minimum needed to rep the benefits of the mass production effect.”
Toyota used this “automotive production cost curve” or the Maxcy-Silberston curve, named after the originators, to limit production volumes and instead increase sales and profit through variety. While this is in overall agreement with Taiichi Ohno’s philosophy of the Toyota Production System as “going beyond scale-based production”, this emphasis on theory may have represented a threat to Ohno’s vision of the Toyota Production System, born from practice and implementation, not theory.
Another reason for Ohno’s insistence on practice, not theory may have been because of a cultural shift at Toyota in the 1970s and 1980s caused by an influx of university educated young managers such as Fujio Cho joining the Toyota. They may have brought with them their theories learned in universities. If so, Ohno was tough on his subordinates and students such as Fujio Cho for a good purpose, emphasizing learning through practical kaizen rather than theory.
There is the famous story of Taiichi Ohno’s subordinate doing kaizen according to his instruction and being scolded:
“You are a fool if you do just as I say. You are a greater fool if you don’t do as I say. You should think for yourself and come up with better ideas than mine.”