Systems thinking is concerned with understanding or intervening in problem situations, based on the principles and concepts of the systems paradigm. This KA offers some basic definitions of systems thinking. The following diagram summarizes how the knowledge is presented.
Systems thinking considers the similarities between systems from different domains in terms of a set of common systems concepts, principles and patterns:
• A principle is a rule of conduct or behavior. To take this further, a principle is a “basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct” (WordWeb.com).
• A concept is an abstraction, or a general idea inferred or derived from specific instances.
Principles depend on concepts in order to state a “truth.” Hence, principles and concepts go hand in hand; principles cannot exist without concepts and concepts are not very useful without principles to help guide the proper way to act (Lawson and Martin 2008).
Many sources combine both concepts and the principles based on them. The Concepts of Systems Thinking topic presents concepts extracted from a variety of theory and practice sources. The Principles of Systems Thinking topic, in turn, presents a summary of important principles referring back to the concepts upon which they are based is also provided.
A pattern is an expression of observable similarities found in systems from different domains. Patterns exist in both natural and man-made systems and are used in systems science and systems engineering. A summary of the different classes of patterns and the use of patterns to support a systems approach is discussed in the final Patterns of Systems Thinking topic.
The practical application of systems thinking often employs the use of abstract system representations or models.
What is Systems Thinking?
This topic is part of the Systems Thinking Knowledge Area (KA). The scope of systems thinking is a starting point for dealing with real world situations using a set of related systems concept discussed in Concepts of Systems Thinking topic, systems principles discussed in Principles of Systems Thinking topic, and system patterns discussed in Patterns of Systems Thinking topic.
Introduction
The concepts, principles, and patterns of systems thinking have arisen both from the work of systems scientists and from the work of practitioners applying the insights of systems science to real-world problems.
Holism (glossary) has been a dominant theme in systems thinking for nearly a century, in recognition of the need to consider a system as a whole because of observed phenomena such as emergence. Proponents have included Wertheimer, Smuts, Bertalanffy, Weiss, (Ackoff, 1979), (Klir, 2001), and (Koestler, 1967) among many others.
A more detailed discussion of the most important movements in systems theory can be found in History of Systems Science.
Identifying Systems of Interest
When humans observe or interact with a system, they allocate boundaries and names to parts of the system. This naming may follow the natural hierarchy of the system, but will also reflect the needs and experience of the observer to associate elements with common attributes of purposes relevant to their own. Thus, a number of system-of-interests (SoIs) (Flood and Carson 1993) must be identified and they must be both relevant and include a set of elements which represent a system whole. This way of observing systems wherein the complex system relationships are focused around a particular system boundary is called systemic resolution.
Systems thinking requires an ongoing process of attention and adaptation to ensure that one has appropriately identified boundaries, dependencies, and relationships. Churchman (1968) and others have also considered broader ethical, political and social questions related to management science with regards to the relative power and responsibility of the participants in system interventions. These are seen by critical systems thinkers as key factors to be considered in defining problem system boundaries.
A system context can be used to define a SoI and to capture and agree on the important relationships between it, such as the systems it works directly with and the systems which influence it in some way. When this approach is used to focus on part of a larger system, a balance of reductionism and holism is applied. This balance sits at the heart of a systems approach. A systems context provides the tool for applying this balance, and is thus an essential part of any systems approach and hence, of SE as well. Approaches for describing the context of the different types of engineered systems are discussed in Engineered System Context topic within the Systems Approach Applied to Engineered Systems knowledge area.
Systems Thinking and the Guide to the Systems Engineering Body of Knowledge
From these discussions one can see systems thinking as both a set of founding ideas for the development of systems theories and practices and also as a pervasive way of thinking need by those developing and applying them. The Guide to the Systems Engineering Body of Knowledge (SEBoK) is particularly interested in how Systems Thinking can support a Systems Approach Applied to Engineered Systems.
In order to examine a SoI in more detail, to understand, use, or change them in some way, practitioners are faced with an apparent “systems thinking paradox”. One can only truly understand a system by considering all of its possible relationships and interactions, inside and outside of its boundary and in all possible future situations (of both system creation and life), but this makes it apparently impossible for people to understand a system or to predict all of the consequences of changes to it.
If this means that all possible system relationships and environmental conditions must be considered to fully understand the consequences of creating or changing a system, what useful work can be done?
In many ways this is the essence of all human endeavors, whether they are technical, managerial, social or political, the so called known knowns and unknown unknowns. The systems approach is a way of tackling real world problems and making use of the concepts, principle and patterns of systems thinking to enable systems to be engineered and used.
The systems principles of encapsulation and separation of concerns in Principles of Systems Thinking relate to this issue. Some of the detail of complex situations must be hidden to allow focus on changes to a system element. The impact must be considered of any changes that might be made across sufficient related system components to fit within the acceptable commercial and social risks that must be considered. Engineering and management disciplines deal with this by gathering as much knowledge as necessary to proceed at a risk level acceptable to the required need. The assessment of what is enough and how much risk to take can, to some extent, be codified with rules and regulations, and managed through processes and procedures; however, it is ultimately a combination of the skill and judgment of the individuals performing the work.