Paolo Soleri used the term Lean Alternative to describe his version of a sustainable society. While they are very similar in outlook and perspective, the underlying theme of Lean Alternative is embedded in the ideas of Leanness and Frugality. This concept emerged from earlier School of Thought gatherings which emerged from a group discussion on the book Natural Capitalism. In the book, the term Muda was used to describe an effort by the Japanese to become more efficient by designing industrial systems to use less and also reduce waste (Muda = Waste).
The terms "Lean Hypothesis" and "Lean Society" also show Soleri's emphasis on frugality and lean thinking as a way to rethinking existing socioeconomic values and priorities.
To Soleri the term Sustainable Society was not to be trusted, because he felt that term sustainable was a vague term that had little real meaning and had been bastardized. Its often being used as corporate marketing and public relations to justify endeavors or ideas that were not really sustainable but were marketed as such in order to increase brand loyalty and goodwill - some refer to this as "greenwashing". Soleri discussed this in detail in referring to a better kind of wrongness as a approach, product or technology that while being called Green or Sustainable was not really much different than the prevailing or conventional of way of doing things.
Soleri when speaking of the Lean Society, referred to a society driven by his ideal state of leanness. It would be logical to infer that such a society would be defined by Arcology styled developments and would look and feel very different than today's capitalistic and commercial dominated societies. It also would most likely have values and goals that would be very different than the ones the current American is now dominated by such as consumerism and suburbanization, thus the name: Lean Alternative.
Values of Leanness:
Elegant Frugality & Doing More with Less - uphold the value of simple living without the need or desire to accumulate lots of things.
Muda - Developed by the Japanese it was featured in the book Natural Capitalism and discussed in early School of Thought discussions. Its basically the idea of designing systems to minimize waste in the manufacturing process
Negentropy - this includes devising ways and technologies to efficiently use natural capital in regenerative ways that increase the dynamism of ecosystems that we rely on for life . This was a term discussed by Francis Frick in his South China Arcology which seeks to put forward the idea of designing human systems that not only minimize environmental impacts, but seek to design human systems increase mimic the resilience and dynamism of natural systems
Hard Work - the idea of hard not as a end in itself but with a purpose of building more lean societies that better serve humanity desire for wellness and prosperity, but without destroying nature in the process
Densification - by creating more complexity within a given spatial area, we can do more with less.
In discussing the prevailing approach to mainstream approaches to public policy and even in relation to more conventional sustainability models he would explore his Lean Alternative.
The Lean Hypothesis is similar to terms used by Soleri defining Arcosanti as a Urban or experimental Laboratory. The Lean Hypothesis would first be tested in a prototype Arcology such as Arcosanti was originally intended to be (Arcosanti was to be the "World's First Prototype Arcology"). It was this idea of testing his idea of leanness in the development of projects similar to his Arcology prototypes such as Arcosanti 5000 or Lean Linear City.
References:
Muda was featured in Chap 7 of the book Natural Capitalism: http://www.natcap.org/images/other/NCchapter7.pdf
Wikipedia definition of Muda: https://en.wikipedia.org/wiki/Muda_%28Japanese_term%29
Muda 7 Wastes of Lean: http://www.systems2win.com/LK/lean/7wastes.htm