Thinking systemically: Limits to Growth
Some of you, especially those of you with whom I've worked, may have heard me talk about the difference between a computer model designed to give predictions about the future and one designed to increase our understanding about the likely effects of policies we choose on the future. If you design the former, you expect its results to come within some percentage of the actual results when the future becomes the present. System dynamics models typically aren't designed with that in mind, although some do an amazingly good job at it. Such models are typically designed to help us understand whether certain information feedback structures are likely to generate a stable system or one that exhibits certain other behaviors, including growth, decline, growth and decline, or even oscillations. That's a hard difference to describe; we all see the graphs produced by a model and think it's predicting the future rather precisely.
I just finished reading Limits to Growth: The 30-Year Update, and I must say that the authors have done a very good job of explaining the difference. Of course, it took them the better part of 300 pages.
I'd encourage everyone to read this book for multiple reasons. First, it provides a good explanation of system dynamics and systems thinking in a rather nontechnical manner. While they offer a way to get the model, if you want to try it yourself, I suspect many will satisfy themselves by reading the book and thinking about the ideas.
Second, it explains the authors' mental models of the world in which we live and their view of the implications of the world's apparent focus on growth as a natural goal. Unlike many books on both sides of this fence, they don't sound as if they're dogmatically pushing a particular position. Rather, they discuss their rather clear if high-level model of the world, and they explore implications of various responses we as people might take to what they see as likely to occur. They highlight areas of their uncertainty, and they make enough information available so you and I can consider their reasoning, not just accept or reject their statements. They do paint a rather grim picture if we as peop1e on this planet don't react well, but they also paint a picture of opportunity for all of us even as we live near the limits of what this planet can support.
To be clear, while I think this book does a very good job of using system dynamics in a nontechnical manner, I think its most important value is its helping us to think about a very important problem that's increasingly in the news.
Third, they list tools they see as important for a successful transition to a sustainable world. In addition to the possibly obvious ones used in the book—"rational analysis, data gathering, systems thinking, computer modeling," and clear writing (p. 271)—they mention five other tools:
Now that I seem to have given away the punch line at the end, I will emphasize that I don't think you'll get as much as you can out of the book if you start with the last chapter, and I know you'll need to read that last chapter to understand what the authors meant by those terms. Get a copy, read the book starting at the front, think, get a copy of the model and wrestle with it, if you wish, and then consider the opportunities we face.
limits to growth