Book Review: Thinking in Systems by Donella H. Meadows
Book Summary
Ever since the summer of 2010, I was interested in Systems Thinking. I got the first whiff of the subject in an eye-opener of a course by Prof. L. S. Ganesh. It has been so long that I do not remember the details of that course, but it instilled a curiosity that made me study more, read more, and experiment more. Here is the professor talking about Why Learn Systems Thinking.
So far, after taking the course and reading this book, I have realized that the definition of systems thinking is difficult to put into words and yet easier to observe and understand. I will try to do my best in defining it. Formally defining, a “system” is an interconnected set of elements that is coherently organized in a way that achieves something. From a recursive viewpoint, Systems Thinking is, literally, a system of thinking about systems. It is thinking about different entities, processes, and problems as part of a larger interconnected whole rather than in isolation.
A simple example of a system, as mentioned in the book, is a Thermostat/Air Conditioning System in a house. The purpose of this system is to maintain a constant temperature in the room relative to the outside environment. Let’s break it down using basic systems thinking concepts.
- The Goal (or Purpose)
The system’s entire purpose is to maintain a desired temperature (e.g., 22°C). This goal is what drives all its actions.
- The Stock
In any system, the stock is the central quantity or level that you can measure. For the thermostat system, the stock is the actual, current temperature of the air in the room. This is the thing the system is constantly trying to manage.
- The Flows
Flows are the actions that increase or decrease the stock. In this case:
Heat flowing in from the hot outside environment (this is an inflow of heat that raises the stock/temperature).
Cool air flowing in from the AC unit (this is an outflow of heat that lowers the stock/temperature).
- The Feedback Loop (The “Brain” of the System)
This is the most important part. The system doesn’t just turn on the AC and leave it running. It uses information about the stock to control the flow. This is a feedback loop. Specifically, it’s a balancing feedback loop because it tries to keep the system stable and at its goal.
Here’s how the loop works, step-by-step:
Measure: The thermostat’s sensor constantly measures the stock (the current room temperature).
Compare: It compares this measurement to the goal (the temperature you set). The difference between these two is the “gap.”
Act: If a gap exists (i.e., the room is too hot), the thermostat sends a signal. This signal activates a flow—it turns the AC on.
Correct: The AC pumps cool air, causing the stock (room temperature) to decrease.
Stop: Once the sensor detects that the temperature has reached the goal, the gap is closed. The thermostat sends a new signal to stop the flow—it turns the AC off.
The cycle then repeats as soon as the room heats up again. This continuous loop of measuring, comparing, and acting is what keeps the room’s temperature stable.
- Delay
Systems rarely respond instantly. When the AC turns on, there’s a delay before the room actually cools down to the desired temperature. Understanding delays is crucial in more complex systems, as they can cause unexpected behavior (like over-cooling or over-heating).
In short, the thermostat isn’t just a switch. It’s a self-regulating system that uses a balancing feedback loop to manage a stock (temperature) by controlling flows (cool air) to achieve its goal. This simple model is the foundation for understanding much more complex systems in our world.
The book gives a basic introduction to Systems Thinking. The first part deals with the basic terms used in systems thinking like purpose, interconnectedness, stock, flow, feedback (balancing feedback and reinforcing feedback), and delays (capital delays and informational delays). The second part deals with the relationship of a system with a systems thinker, detailing why systems work well, how systems surprise us, and what could be system traps and opportunities. The third and final part deals with finding and exploring systems in the world and how we, as systems thinking practitioners, can change the system based on specific system properties.
The book is a collection of so many new concepts, alternate modes of thinking, and new mental models that every chapter could be a book in itself.
My Views about the Book
The world is profoundly complex, and to make sense of it, we create abstractions or mental models. An economist sees the world through the lens of markets and incentives. A physicist views it through the fundamental laws of matter and energy. A biologist understands it via the framework of evolution. Each of these perspectives is powerful, yet incomplete.
Systems Thinking is another such abstraction, but its focus is unique. While other disciplines often zoom in on the individual parts, Systems Thinking zooms out to see the interconnections and relationships that bind them together. It doesn’t seek to replace these other viewpoints but to integrate them, revealing the hidden patterns, feedback loops, and emergent behaviors that arise from the whole. It helps us see the world less like a collection of objects and more like a dynamic, interconnected network. This perspective not only suggests powerful ways to intervene but also teaches the humility that problems are rarely “solved”—they are simply transformed.
I personally enjoyed this book. The number of notes and alternate viewpoints that this text has brought me were immense. The initial chapters, where the book introduced the basics of systems thinking, were a bit of a drag since they introduced the vocabulary used throughout the remaining chapters. The last few chapters were a pure delight; I could see different systems near me and observe their behavior, problems, and solutions from the POV of the text.
Overall Rating
I would like to give the book 5 Stars. This is a book that has to be read, re-read, and lived.