This question was posted on Quora.com: “What are some examples of open and closed systems?” Here is are the top three responses:
An open system is a system that freely exchanges energy and matter with its surroundings. For instance, when you are boiling soup in an open saucepan on a stove, energy and matter are being transferred to the surroundings through steam.
Putting a lid on the saucepan makes the saucepan a closed system. A closed system is a system that exchanges only energy with its surroundings, not matter. By putting a lid on the saucepan, matter can no longer transfer because the lid prevents matter from entering the saucepan and leaving the saucepan.
There are no truly closed systems, except for purely conceptual systems, e.g. the physicist’s imaginary box that is isolated from all outside influences.
Even a rock is subject to e.g. changes in temperature which cause it to expand and contract, the influence of water which slowly dissolves it, and the slow growth of lichen which slowly crumbles its surface.
All real systems are open systems which we often pretend are closed because we 1) want to understand the internal dynamics of the system or 2) want to understand the major external influences on those systems while ignoring the minor influences.
Let us take simple examples.
A closed system allows only energy transfer but no transfer of mass. Example: a cup of coffee with a lid on it, or a simple water bottle.
An open system is one which can allow mass as well as energy to flow through its boundaries, example: an open cup of coffee.
Isolated systems allow neither mass nor energy to flow through their boundaries. Example: a thermos flask.
In reality, a perfectly isolated system does not exist, for instance hot water in a thermos flask cannot remain hot forever.
The only problem with all of the above is that they fail to distinguish between structural closure and operational closure. All three discuss structural closure only. They say nothing about system operations. Actually, I don’t even know why we need to call a cup of coffee with a lid on it a system at all. What operation does it carry out? It’s just a cup of coffee with a lid on it, and the lid simply slows down entropy. It’s just an unplugged machine, which means it’s a useless machine.
Structurally closed “systems” (like a closed pan of soup or hot water in a thermos) exist only conceptually or analytically; however, operationally closed systems exist in reality—or more precisely, they are observable. Social systems theory does not concern realities that exist independent of some observing system. This is what radical constructivism means.
Social systems (and other autopoietic systems) are structurally open and operationally closed. To be structurally open means expectations (social structures are expectations) may be perturbed by the environment. Operational closure means that a social system only communicates with itself; there is no communication between system and environment.
Social systems must have a communication medium. For instance, the communication medium of the modern economy (or commerce) is money. Without some form of money (even if accessed negatively through debt) we cannot participate in the modern economy. Anyone without access to money is excluded from the money-based economy (as distinguished from a barter economy).
Or if a group of people are sitting together speaking Russian and I walk by, I (as a non-Russian speaker) am excluded from that social system. I exist in that system’s environment. As a social system, the system’s sole operation is communication. Only communication can produce new communication.
However, from the above example, you might think that the structure of a social system consists of language, words, or communicative events. But communication is an operation, not a structure. The structures of a social system are expectations, or the sense of “what’s next.”
Expectational structures are open in the sense that they are influenced by other expectational structures. One social system has expectations, and these may be influenced (perturbed, irritated) by the expectations of another social system.
For example, public health researchers or sociologists might expect to see an increase in opiate abuse, which might lead Emergency Room doctors to expect to see an increase in opiate-overdose patients. Or climatologists might expect to see global warming along with sea-level and more violent hurricanes, which might lead real estate investors to expect a decline in value for ocean front properties.
For social systems, what systems expect to see is more important than what they actually see now, because they are always projecting into the future. Consider the stock market; it measures expectations. The economy or a particular company might be doing badly now, but investors are always looking at the future. This is why a pandemic can be keep raging, with unemployment still high and companies going bankrupt, but the stock market can go up because investors expect a profitable future.
This is where systems thinking is most valuable; it’s all about decreasing the randomness of life, or getting better at seeing how things interact in complex ways and preparing for what might come. In an economic context, this kind of thinking goes back to the invention of marine insurance in Greek and Roman antiquity. Marine insurance “covers the loss or damage of ships, cargo, terminals, and any transport by which the property is transferred, acquired, or held between the points of origin and the final destination” (Wikipedia). At some point in history, people decided to not just stoically endure random misfortunes. They decided to actually prepare for what might happen in the future.