Concepts of Systems Thinking

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The Principle of Elements

The concept of an element is fundamental to systems. Elements are the building blocks of systems. Elements may take many forms. They may be hardware, software, humans, processes, conceptual ideas, or any combination of these. According to (Jackson et al., 2010, p. 41), when a system interacts with other sibling systems, the system itself becomes an element in a larger system called a system of systems. Other potential elements are the development system, the training system, the test system, and the support system. Systems Engineering defines the properties of the entire system as well as the individual elements. However, the principle of holism discussed below states that the properties of the entire system cannot be defined from the individual elements.

The Principle of Grouping

The principle of grouping allows the elements of a system to be grouped into subgroups. In Systems Engineering these subgroups are called subsystems. Each subgroup, that is, each subsystem will exhibit its own functions and other properties. Grouping also allows the system to be represented in different ways. In Systems Engineering the grouping can be represented as a hierarchy among other representations discussed more thoroughly in Topic 4. Other representations include the web view and the interface view as discussed below in the principle of interactions. All views are abstract representations of the system.

The Principle of Functions

The principle of functions states that the entire system, its elements and its subgroups will be capable of one or more functions. The Systems Approach calls for the identification of these functions. In Systems Engineering these functions can be analyzed to determine the performance of the entire system and its component parts. Systems Engineering also establishes the functional architecture which is the basis for the incremental development of the physical architecture.

The Principle of Interactions

The principle of interactions states that the elements of a system interact with each other. In addition the subgroups also interact with each other. The entire system interacts with external systems and with the environment. Principle of interactions leads to the Systems Engineering process of Interface Analysis and Management and also to the architectural representations of the interface view. The principle of interactions is also linked to the principle of cohesion discussed below since interaction is a basic property of cohesion.

The Principle of Boundaries

The principle of boundaries states that all systems have boundaries. In Systems Engineering the boundary of a system defines the system of interest (SOI) called the relevant system by (Checkland, 1999, p. 166). The boundary of a system defines the surface at which the system interacts with other systems (see principle of interactions) and with the environment. Subgroups also have boundaries that define the surface where they interact with other subgroups.

The Principle of Cohesion

The principle of cohesion also discussed by (Hitchins, 2009, p. 60) reflects the idea that a system is an interacting set of elements (see principle of interactions) that all act together to perform the functions of the entire system. (Hitchins, 2009, p. 60) describes cohesion this way: “A system’s form is maintained by a balance, static or dynamic, between cohesive and dispersive forces.” In the Systems Approach and in Systems Engineering the principle of cohesion allows the entire system to be synthesized as discussed below in the Systems Approach.

The Principle of Emergence

The principle of emergence states that a system will exhibit properties, called emergent properties that cannot be determined from the elements alone. They can only be determined when the entire system is considered as a whole, called holism, within the Systems Approach. For complex systems these properties may not be predictable. Thus, the Systems Engineering approach to treating them must be dynamic and iterative.

Additional Principles

In addition to the principles discussed above, (Hitchins, 2009) identifies the following for a more comprehensive set of principles; they are defined briefly here. They are included for a more in-depth understanding of systems. Like the principles above, the astute Systems Engineer will incorporate these into the definition of a system of interest (SOI).

  • The Principle of System Reactions. This principle describes the ability of a system to rearrange itself.
  • The Principle of Adaptation. This principle describes the necessity for a system to adapt faster than the rate of change of the environment.
  • The Principle of Connected Variety. This principle describes the ability of connected systems to achieve stability through increased variety.
  • The Principle of Preferred Patterns. This principle describes how the stability of interacting systems is enhanced by increased cohesion.
  • The Principle of Cyclic Progression. This principle describes how systems, primarily political and economic systems, cycle in response to variations in input energy and feedback loops.

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