What is a system?

By Matt Johnson

What is a system? I posted a similar question on The Systems Scientist Facebook page last week. I asked the following question,

In your own words, explain, or describe, what you think a system is?

In response, I received a lot of good and interesting answers from Facebook followers. One Facebook follower stated,

A limited framework of interrelated processes that work toward a mutual output or outcome.

As the reader will see, this answer hits the third axiom of what a system is, and the answer also touches upon the structure and processes of a system as well.

Another Facebook follower hit the mark on two of the systems’ axioms on the first try: the first axiom and the third axiom. As the follower explained,

A system to me is a set of parts, each with a different function, that work in concert, complimentary way towards a common goal.

All together, there were a lot of really good answers and everyone who commented pointed out that a system has a function, or purpose. And many of the Facebook followers added that systems consist of parts and those parts are what compose the system itself, which is correct. So what is a system?

Photo Credit: Wikimedia Commons. Seattle, Washington

To answer this question, we will utilize Donella Meadow’s three conditions from her book Thinking in Systems: A Primer to propose the systems’ axioms, we will be using going forward. And by axiom we mean a statement that is true and will follow our thinking and logic from thusly. Here are the axioms we will be using:

  1. A system consists of a set of elements.
  2. Elements in the system interact.
  3. A system has a function, or purpose.

At first, these axioms seem so obvious and simple, and that’s good, but these axioms are subtly profound. This is because they can be described through mathematics and tested via the scientific method. But perhaps putting the math and science aside for the moment would be beneficial. Instead, a familiar example will suffice.

Again, in order to have a system, the three axioms must be satisfied. For instance, does the United States House of Representatives satisfy each condition?

For the first axiom, all we have to do is count the total number of members that serve in the House, which is 435. In other words, there are 435 elements in our example. Thus, we see that axiom (1) is satisfied. For the second axiom, we should ask ourselves if the members of the House interact with each other?

Is there another answer to a question that has ever seemed so obvious? From the debates on the House floor to Twitter wars, the members of the House of Representatives do indeed interact with each other. There are a plethora of examples to illustrate this point in the form of C-SPAN, MSNBC, FOX, and CNN. Thus, we see that axiom (2) is satisfied.

And finally for the third axiom, does the House of Representatives have a function? It definitely feels like they don’t have a purpose on most days. But they do and this purpose of course derives from the United States Constitution. Thus, we see, although begrudgingly, that axiom (3) is satisfied.

Photo Credit: Chandra X-Ray Observatory. Milky Way Galaxy

Over time and as these blogs progress, we will see that these three axioms will be extremely useful for us. They will allow us to explore cities and economic systems, and most importantly they will allow us to construct describable phenomena via mathematics, test observable data, and make predictions that might not otherwise be accessible through cluttered language, hyperbolic rhetoric, and undefined terms.

One final thing, these three axioms are not the totality of a system. Systems have inputs and outputs, a structure, environment, behaviors, processes, boundaries, and other properties. Together, all of these characteristics are what make a system. But these axioms are a good start and will allow an interested party into the world of Systems Science.

Until the next blog, do the classical science thing and test these axioms for yourself. In other words, try to disprove them. If you can manage to find an example, please do share it in the comments section below so the other readers and commentors can validate your findings.


Matt Johnson is a blogger/writer for The Systems Scientist and the Urban Dynamics blog. He has also contributed to the Iowa State Daily and Our Black News. And he has a Bachelor of Science in Systems Science, with focuses in applied mathematics and economic systems, from Iowa State University. 

You can connect with him directly in the comments section, and follow him on Facebook

You can also follow The Systems Scientist on Twitter or Facebook.


Photo Credit: Wikimedia Commons





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