I read a couple of Weinberg's books. He did some on-site consulting in organization development at my employer's of the time.
I preferred his "Psychology of Computer Programming" for accessibility. ( )

This book has lots of good content -- I was highlighting frequently -- but it's not the easiest read.

The high level idea of general systems thinking is that there are large classes of problems that are difficult to analyze. Problems with small number of pieces and lots of structure -- organized simplicity -- can be handled analytically. Problems with many pieces and lots of randomness -- unorganized complexity -- can be handled statistically. Those systems in between -- medium systems -- are too large to be handled analytically but not large enough to be handled statistically.

To illustrate this with an example from the text, one can fully analyze the way that the flu spreads through a very small group of people, e.g., a family. Alternately, one can statistically analyze the way the flu spreads through a population. But figuring out how the flu spreads through a medium sized group -- a school for example -- is difficult, and a system that was analyzable at other scales suddenly has complex and surprising behavior.

As "The Law of Medium Numbers" puts it: "For medium number systems, we can expect that large fluctuations, irregularities, and discrepancy with with any theory will occur more or less regularly."

So where does that leave us? General systems thinking is the field of creating models and understanding the limitations of those models. An important part of this is understanding how different models can seem contradictory yet both be correct. Along the way, Weinberg diverts into discussions of scientific theories and social subcultures. These passages alone make the ideas in the book worthwhile, and I expect that we would have a lot less controversy over models like evolution and climate change if people understood better how models work. ( )

I read this book in the 1980s, probably, and now am writing this review in 2021. This is a book that changed my way of thinking. It's written in an almost jokey style, but is a very serious description of how to think about complex collections of people, ideas, processes, and objects. I learned here to view much of what goes on in the world as systems. ( )

Another gem from Gerald Weinberg. This one is about "systems", in a very general sense. Anybody doing science or engineering (or pretty much anything that involves some type of analysis) will find material of interest here.