Systems Thinking Example 3: The Faucet

In the previous two examples I have introduced two basic systems thinking principles. The automobile example from Russell Ackoff demonstrated that a system is not the sum of its part but the product of their interactions. The second example was from Donella Meadows, and the lesson was that the behavior of the system can only be changed by changing the system itself. In this blog post I will briefly touch upon how to think about any situation using systems thinking with an example from Peter Senge’s book The Fifth Discipline.

Let’s begin again with a thought experiment. Imagine that you’re thirsty and decide to have glass of water. You take a glass, go to a water tap and fill the glass in order to have a drink. If we were thinking linearly, we would see a simple cause and effect relationship: you filling a glass of water. However, the situation looks different from a systems point of view. (The below pictures are from Senge’s book The Fifth Discipline.)


When you’re filling the glass with water, there are actually several things happening at the same time. You have a desired water level in mind, so while the water is pouring into the glass, you’re monitoring the ‘gap’ between the current water level and your goal. As the water level rises, you are adjusting the faucet with your hand and finally closing it when the water has reached the desired level. You are, in fact, engaged in a system that has five variables:

  1. the desired water level
  2. the current water level
  3. the gap between the two
  4. the faucet position and
  5. the water flow

Faucet 2

The above picture illustrates how the different elements of the system influence one another. You can begin reading the picture from anywhere. An arrow indicates the direction of influence. Desired water level influences the perceived gap, which influences the faucet position, which again has an influence on the water flow. When the water flow changes, it in turn has an effect on the current water level, which finally influences the perceived gap.

This is how systems thinkers view situations, problems and the world in general. Instead of one time events and simple cause-effect relationships, they see circles of causality. This thinking can be applied to practically every major problem out there.

Think about terrorism for instance: most of the time we only pay attention to the one time incidents and terrorist attacks we see in the news. What we don’t know is what has been influencing the terrorists in a way that causes them to take violent action. With only superficial knowledge about the reasons behind terrorism, we then respond in fear and anger, which often only increases the terrorists’ conviction.

Not all situations work this way though. If you were to kick a ball, the ball would simply bounce away. Here a simple cause-effect analysis would be sufficient and the event could be explained with physics. However, if you were to kick a dog, the poor creature would react in some way. It might run away, but it could also attack you. You are influencing the dog’s behavior by kicking it and in return the dog will influence your behavior by attacking you. If I were to walk in a room where I only see the dog attacking you, I might easily jump into conclusions about the dog too quickly. This is how we humans perceive the world most of the time, which is why our problem definitions are often so badly off the mark.

The Principle: Instead of seeing one time events, look for circles of causality.

Other implications of this principle:

  • Next time when someone is angry at you, try to look for ways you might have influenced his or her behavior.
  • In the news you see only one time events and the end results of some larger phenomenon. Instead of talking about the event itself, try to think about what kind of circles of causality might have caused the event.
  • In an arms race between nations there is no one country or individual to blame. It is the result of all the countries influencing one another.

Ps. Take a look at this short introductory video for systems thinking:

Creative Commons Dripping Tap by Fred Dawson is licensed under CC BY 2.0.

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