We are filters. Our eyes only pick up a small part of the spectrum of light. We ignore, or we fail to be aware of, something like 98% of the sensory input that we receive. This is apparently to keep us from going mad. Our digestive systems are essentially filters that incorporate the nutrients but not the roughage. For the most part, we are pretty good filters. When it comes to determining truth, it is another matter. For more on that, read Schein, Kahnemann and others.
Today "Lean" makes the front page of major business & technology media under it's increasingly popular definition as "a modern way of designing, launching, marketing" a new product or service. This is because people with the "startup" filter ingested traditional Lean and did a fantastic job of explaining what they saw to the startup community, less the operations management and sustainability roughage.
For the past decade or so, thanks to thinkers, writers and practitioners whose filters were for anthropology, organizational behavior, socio-technical systems, and learning theory, Lean has been dragging itself out of the operations-and-supply-chain world. It was not until value stream mapping was popularized that the production engineering process fixing tool filter of Lean started to be replaced with one that looked at material and information flow across the supply chain.
There has been a false dichotomy of “IE vs. HR” in the Lean world going back decades. The US market filtered what they saw of TPS via the lens of JIT / kaizen / TPS / Lean in the 1980s, thanks to books from Productivity Press, with a heavy tool focus. There were books on the importance of people development but these lesson were mostly ignored as their prescriptions did not fit within a 5-day kaizen event. What the kaizen event filter allowed in was mostly a watered-down version of the scientific method and practical applications of system theory (flow, pull, stop and fix, takt, WIP controls, etc.), often missing the fact that the latter emerged from efforts with the former. We filtered for solutions, not problem solving processes.
The recent pivot from a total enterprise improvement system to a startup approach notwithstanding, why has Lean stumbled around in the dark so long, missing vast parts of the system? Filters.
What filters are we using? Most of us are unaware. We filter out our filters. This is why it is so important to study cognitive biases, the impact emotion has on our decisions, and how fear makes people act in stupid ways, and how clever marketing trumps complicated truth 8 times out of 10 (and the fact that humans are terrible at grasping what statistics mean) and so forth.
They key is to be more deliberate about this (mindfulness, personal transformation, culture change) rather than just being satisfied with getting these as a side benefit of bottom-line-focused kaizen, as are most organizations today.