Thinking in Systems: A Primer
By Donella H. Meadows
This is the first book I picked up when I was looking to get an introduction to systems thinking. It provides a good overview and taught me some basic mental models that surface a lot in daily work.
View on AmazonSystems happen all at once
Words and sentences must, by necessity, come only one at a time in linear, logical order. Systems happen all at once.
Judge the results, not the rhetoric
Purposes are deduced from behavior, not from rhetoric or stated goals.
If you want to judge the effectiveness of a system, watch how people in the system behave and pay attention to the results that the system actually generates. The stated goals are not the system.
Look for non-obvious ways to influence the system
The bathtub example
Therefore, we sometimes miss seeing that we can fill a bathtub not only by increasing the inflow rate, but also by decreasing the outflow rate.
This is from an example of a basic system where there is a bathtub and you are trying to control the level of water in the tub. If you want to raise the water level it might seem more intuitive to adjust the tap to increase the water flow. But it is easy to miss that an equally effective way to raise the water level would be to adjust the stopper where the water lets out. I think about this all the time and it reminds me to attack problems from angles that don't always seem obvious. We tend to focus on in the inflows more than the outflows.
Stocks and delays
The level of the water in the bathtub is called a "stock" and it is interesting to note that althought you can make changes to both the inflow (the tap) and the outflow (the drain), the change in the water level happens slowly after you make the change. So any time you make a change to a system you need to account for the lag or delay that prevents you from observing the effects right away. Don't give up too soon.
Systems thinkers see the world as a collection of stocks along with the mechanisms for regulating the mechanisms in the stocks by manipulating flows.
How to decide if you're looking at a system or just a bunch of stuff:
- Can you identify the parts?
- Do the parts affect each other?
- Do the parts together produce an effect that is different from the effect of each part on its own?
- Does the effect, the behavior over time, persist in a variety of circumstances?
The self-perpetuating nature of systems
An important function of almost every system is to ensure its own perpetuation.
Systems tend to consist of mechanisms designed to ensure the survival of the system. Many times these mechanisms run contrary to the stated goals of the system.
Reference
Meadows, D. H. (2008). Thinking in Systems: A Primer. United Kingdom: Chelsea Green Pub.