Complex systems have the characteristic of being integrated systems which are composed of multiple, diverse parts that are highly interconnected, and capable of adaptation. Examples of this include financial markets with lots of different highly interconnected traders adapting to each other’s behavior as they interact through buying and selling; or an ecosystem with multiple different species that are all interdependent and adapting to each other and their environment; or a supply chain network with many different producers and distributors interacting and adapting to each other in order to deliver a product.
Firstly, complex systems constitute a special type of system. A system is just a set of things that perform some collective function. So the human body is a system in that it consists of many individual organs that work together as a functioning entirety. A business is another example of a system, in which many different individuals and department functioning as an entirety to collectively produce some set of products or services. And of course, there are many other examples of systems such as eco-systems, hydraulic systems, social systems and so on.
Not everything is a system though. If we take a random collection of things, say a hard drive, a light and a watch and put them together, this is not a system. It is rather a simple set of elements as they are not interconnected and interdependent in performing some collective function. It is because of the fact that the elements within a system perform some collective function that systems are said to be greater than the sum of their parts, that is to say that the system as a whole has properties and functionality that none of its constituent elements possess.
A plant cell is an example of this. It is composed of many inanimate molecules, but when we put these together we get a cell that has the properties of a living system. There is no single element that has the properties of life but it is the particular way in which these molecules are arranged that gives rise to the emergent property of a living system as an entirety. A key thing to understand about systems thinking is that it represents an alternative to our modern scientific method, that is primarily focused upon breaking systems down into their constituent parts in order to analyze them, and then tries to understand the whole system as simply the sum of these individual elements.
This approach works well when we are dealing with sets of things that do not have emergent properties. But because some, and in fact quite many systems have these emergent properties as an entirety, this method, which is also called reductionism, does not always work best. In these cases we need to use systems thinking which places a greater focus upon understanding systems in their entirety and within the environment that gives them context.
Complexity is the product of a number of different factors. Firstly, the number of elements within our system. This is quite straightforward. The more parts there are, the more complex it will be. Secondly, complexity is a product of the degree of connectivity between these elements. The more interconnect and interdependent they are, the more complex our system will be. Within simple systems, there are few connections between elements, and it is relatively easy to understand the direct relations of cause and effect, that is to say, we can draw a direct line between a single cause and a single effect. Thus, we call these simple organizations, linear systems. But when we turn up the connectivity within the system and especially when there are a high number of elements, these cause and effect relations become more complex as there may be multiple causes for any given effect or vise versa, as opposed to our simple linear system. We call these more complex organizations nonlinear systems, and non-linearity is a key property of complex systems.
Complexity is also a product of the degree of diversity between elements. When all the elements within our system are very similar or homogeneous, then it is much simpler to model, design or be managed, as opposed to dealing with a heterogeneous organization composed of many diverse parts, each with its own unique set of properties.
Autonomy & Adaptation
Complexity is furthermore a product of the degree of autonomy and adaptation of the elements within the system. When the elements have a very low level of autonomy, then the system can be designed, managed and controlled centrally in a top-down fashion. But as we increase the autonomy of the elements, this becomes no longer possible as control and organization become distributed, which is increasing interactions on the local level that come to define how the system develops.
This gives rise to another important feature of complex systems which is self-organization. When elements have the autonomy to adapt locally, they can self-organize to form global patterns. The process through which this takes place is called emergence. Thus, as opposed to simple linear systems where order typically comes from some form of top-down, centralized coordination, patterns of order within complex systems emerge from the bottom up. Self-organization is another recurring theme across all types of complex systems.
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