How Toyota influenced Scrum. Lean and other roots of Scrum

"Scrum is founded on empiricism and lean thinking. Empiricism asserts that knowledge comes from experience and making decisions based on what is observed. Lean thinking reduces waste and focuses on the essentials." (p. 3 of the Scrum Guide)

Scrum for software was directly modeled after "The New New Product Development Game" by Hirotaka Takeuchi and Ikujiro Nonaka published in the Harvard Business Review in 1986. Nonaka was hired by the Japanese government after World War II to help analyse why they lost the war.

I was puzzled by the fact that Takeuchi and Nonaka have written many books and papers about Toyota, Honda, and other lean companies, yet they never talk about lean. They talk about Scrum, which means to them cross-functional teams engaging in the dynamic conflict of ideas that generates "ba", the energy flow that surfaces knowledge that forms new products. It's the innovation they are interested in and what westerner's call lean are a bunch of context dependent techniques that are side effects of knowledge generation.

So I dug into this puzzle a little deeper by carefully studying where this "lean" idea came from as it appears to be a western idea and not so much a Japanese idea. It all goes back to an MIT institute founded in the late 1980s to study why the Japanese automotive industry was starting to dominate world production.

Taiichi Ohno, the inventor of the Toyota Production System says everything he knows he first learned at Ford. Then all he did was go back to Japan and remove waste. The story of his work is summarized in “The Machine That Changed the World” where Womack discusses what Ohno did after he returned from studying mass production at Ford.

A cross functional team process and continuous improvement was observed not only at Toyota, but in many of the best companies worldwide by Takeuchi and Nonaka while they taught at the Harvard Business School in the early 1980s.