This is a book summary of Thinking in Systems: A Primer by Donella Meadows. I loved it and immediately added it to my recommended reading list.I saved so many notes from the book that I had to cut a bunch of them just to make this summary more manageable—there are tons of examples and graphs in the book that I simply couldn’t include due to length. The Limits to Growth (LTG) is a 1972 report on the exponential economic and population growth with a finite supply of resources, studied by computer simulation. Commissioned by the Club of Rome, the findings of the study were first presented at international gatherings in Moscow and Rio de Janeiro in the summer of 1971. About Thinking In Systems A Primer Pdf. In the years following her role as the lead author of the international bestseller, Limits to Growth―the first book to show the consequences of unchecked growth on a finite planet― Donella Meadows remained a pioneer of environmental and social analysis until her untimely death in 2001. Thinking in Systems: A Primer by Donella Meadows Synopsis: In the years following her role as the lead author of the international bestseller, Limits to Growth—the first book to show the consequences of unchecked growth on a finite planet— Donella Meadows remained a pioneer of environmental and social analysis until her untimely death in.

1-Page Summary1-Page Book Summary of Thinking in SystemsFast Summary of Shortform's Guide to Thinking in Systems

Thinking in Systems is an introduction to systems analysis. Many aspects of the world operate as complicated systems, rather than simple cause-effect relationships. Many problems in the world manifest from defects in how the systems work. Understanding how systems work, and how to intervene in them, is key to producing the changes you seek.

What Is a System?

A system is composed of three things:

1. Elements: The individual things in the system
2. Interconnections: The relationships between the elements
3. Purpose or Function: What the system achieves

To define it more cohesively, a system is a set of elements that is interconnected in a way that achieves its function.

Many things in the world operate as systems.

• A football team consists of a group of players on the field, each with a specific role that interacts with the others. The larger team system also consists of coaches, support staff, and fans.
• Within the system of a corporation, people, machines, and information work together to achieve the corporation’s goals. This corporation then takes place within the larger system of the economy.

Stocks and Flows

Stocks and flows are the foundation of every system.

A stock represents the elements in a system that you can see, count or measure. It can be commonly thought of as an inventory, a store, or a backlog.

Flows are the means by which the stocks change over time. Inflows increase the level of stock, while outflows decrease the level of stock.

Let’s take a simple system: a bathtub.

• The stock is the amount of water in the tub.
• The inflow is water coming from the faucet into the tub. This raises the stock.
• The outflow is the drain that removes water from the tub. This decreases the stock.

This can be drawn on a stock-and-flow diagram, as here:

Many systems are analogous to the bathtub:

• In fossil fuels, the stock is the reservoir of fossil fuels. Mining lowers the stock, while natural processes increase the stock.
• The world population is a stock of people. The population grows with births and shrinks with deaths.

Properties of Stocks and Flows

Stocks take time to change. In a bathtub, think about how quick it is to change the inflow or outflow. It takes just a second to turn on the faucet. It takes minutes to fill the tub.

Why do stocks change so gradually? Because it takes time for the flows to flow. As a result, stocks change slowly. They act as buffers, delays, and lags. They are shock absorbers to the system.

From a human point of view, this has both benefits and drawbacks. On one hand, stocks represent stability. They let inflows and outflows go out of balance for a period of time.

• Your bank account stores money and gives your life stability. If you get fired from your job, the inflow of money will stop, but you can take money from your stock to continue living and figure out how to solve the problem.

On the other hand, a slowly-changing stock means things can’t change overnight.

• If a population’s skills become meaningless because of technology, you can’t re-educate the workforce instantaneously. It takes time for the information to work its way through the system and to flow to the population.

Where We Focus

As humans, when we look at systems, we tend to focus more on stocks than on flows. Furthermore, we tend to focus more on inflows than on outflows.

• When thinking about how the world population is growing, we naturally think about how increasing births must be driving the trend. We think less about how preventing death through better medical care also grows the population.
• Likewise, a company that wants to increase its headcount does so instinctively by hiring more people. It doesn’t often think as hard about how to reduce the outflow of people who quit or are fired.

This is just one example of how we, as simplicity-seeking humans, tend to ignore the complexity of systems and thus develop incomplete understandings of how to intervene.

Feedback Loops

Systems often produce behaviors that are persistent over time. In one type of case, the system seems self-correcting—stocks stay around a certain level. In another case, the system seems to spiral out of control—it either rockets up exponentially, or it shrinks very quickly.

When a behavior is persistent like this, it’s likely governed by a feedback loop. Loops form when changes in a stock affect the flows of the stock.

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Balancing Feedback Loops (Stabilizing)

Also known as: negative feedback loops or self-regulation.

In balancing feedback loops, there is an acceptable setpoint of stock. If the stock changes relative to this acceptable level, the flows change to push it back to the acceptable level.

• If the stock dips below this level, the inflows increase and the outflows decrease, to increase the stock level.
• If the stock rises above the acceptable level, the inflows decrease and the outflows increase, to decrease the stock level.

An intuitive example is keeping a bathtub water level steady.

• If the level is too low, plug the drain and turn on the faucet.
• If the level is too high and the water spills out of the tub, open the drain and turn off the faucet.

Reinforcing Feedback Loops (Runaway)

Thinking In Systems Donella Meadows Free Download

Also known as: positive feedback loops, vicious cycles, virtuous cycles, flywheel effects, snowballing, compound growth, or exponential growth.

Reinforcing feedback loops have the opposite effect of balancing feedback loops—they amplify the change in stock and cause it to grow more quickly or shrink more quickly.

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• As a stock level increases, the inflow also increases (or the outflow decreases), causing the stock level to further rise.
• In the other direction, as a stock level decreases, the inflow also decreases (or the outflow increases),...