# Basic Structures of Systems

Chapter
Part of the Studies in Systems, Decision and Control book series (SSDC, volume 275)

## Abstract

The essence of system science resides in the philosophy of holism. When talking about the state that system reaches optimal, it generally refers to global optimum of the whole system with respect to the objective features that are included in the intrinsic features of a system. The attainment of global optimum of a system must rely on the normal deployment of functions (features) of its subsystems. The word ‘system’ originates from Latin word syst$$\overline{e}$$ma meaning that a whole is made of several parts or members. Many different definitions had been made by scholars for system from different perspectives based on their particular research objectives. Let’s give some examples of them. “System is a pre-given set composed of elements and their normal behaviors”; “System is a well-organized wholeness”; “System is an entity made of connected materials and processes;” “System is a body composed of ordered elements/factors working towards a common goal” are some popular examples for the definition of system. The development of system theory and their applications in different field were mainly attributed to the contributions of scholars such as biologist Ludwig von Bertalanffy (1901–1972), Norbert Wiener (1894–1964), Ross Ashby (1903–1972), John Henry Holland (1929–2015), and Murray Gell-Mann (1929–2019). Bertalanffy pioneered the general system theory by introducing models, principles, and laws that apply to it. Wiener and Ashby used mathematics to study systems. Holland, Gell-Mann, and others proposed the term “complex adaptive system”. General system theory attempts to provide a definition that can capture common properties of various systems. The definition for general system is: a body composed of well-organized elements working toward attaining particular goals or features. This definition apparently includes 4 concepts and their relationships, namely system, element, structure, feature, relationships between elements, relationships between elements and structure, and relationships between system and external environment. The purpose of system theory is to investigate form, structure, and laws of general systems, to examine the common properties of those systems, to capture and illustrate their features using mathematical methods, and consequently to identify the mechanisms, rules, laws, principles, and mathematical models that can be applied to general systems. And the ultimate objective of learning system theory is to use the understanding on the system to better manage, control, renovate, or change the current system structures (natural or man-made systems) to align them with the needs of our civilized world. With better understanding on the system structures, we can introduce all kinds of interventions or policies to enable the systems of interest attain their optimal performance or outcomes. Moreover, by gaining better understanding on the dynamics of a system over time, decision/policy makers and practitioners can prevent policy-resistance (counter-intuitive behaviors). System theory is recognized a discipline that possesses both mathematical and logic characteristics. System theory proclaims that holism, connectedness, hierarchical structure, and dynamic equilibrium, time-dependence are common properties of all systems, which are both philosophy of system thinking and principles of using system approach. As a branch of scientific approaches, system theory helps identify the objective laws on how world is running and also offers human being a way of thinking the world. Therefore, system theory is also called system approach since it can represent concept, view, model, and mathematical methods as well. In Bertalanffy’s masterpiece titled “General System Theory; Foundations, Development, Applications”, he emphasized the concept of holism. System, as a organic body, is not mechanical combination or simple addition of its constituents but an organic combination of its elements working together towards a common goal. The system’s features are emerging behaviors, which can not be found in its individual elements or subsystems. By quoting Aristotle’s “A whole is greater than the sum of its part,” Bertalanffy opposed those mechanical philosophy that the wholeness (system behaviors) can be observed or inferred from the behavior of a particular element of the system. He also stated that each element of a system is in a particular location in the system hierarchy, which is also tightly coupled with other elements. The connectedness among system’s elements renders system integral and holistic. The “should-be” function of a system’s element will disappear once it is separated from the system structure. For example, having done the hand amputation due to traumatic injury, the removed ‘limb’ would never function as it should when it was an integral part of a person. The fundamental thoughts of system theory is to treat the object being investigated as a system and to analyze the structure, function, dynamic relationships between elements, system, and their environment. With better understanding on the dynamics, complexities, and uncertainties associated with the system, the ultimate goal is to find how it attain its optimal target and, consequently provide counterfactual analysis when interventions are needed to be implemented in the system. Systems are ubiquitous in the universe. From cosmos to the microscopic world, systems exist everywhere such as Milky Way, solar system, earth system, social system, transportation system, production system, human body system, bacterial system, cell system, and atom. The emergence of system theory brought profound changes on the way how people think about the world. In conventional research practices, Descartes’ philosophy of ‘reductionism’ had been dominating the academic fields. Under such influence, the general practice in research is to divide a complicated issue or object into multiple parts and investigate each part individually. Thereafter, the characteristics of those individual parts are then used to infer the behaviors of the original issue or object. The reductionisim approach focuses on local substructures or elements and abides by the unidirectional causal-effect determinism. Although this approach had proved valid for centuries within certain confined ranges and had served as the most popular way of thinking in mainstream research communities, it can only handle simple issues or objects without being able to capture the wholeness, dynamic interactions, and circular causalities of complicated objects (i.e., systems in the language of system theory). With accelerated development in economy, technology, and society, human beings with traditional analytical thinking became incompetent in dealing with issues/objects with thousands or even millions of variables connected/networked in various ways. However, the emergence of system theory, cybernetics, and informatics paved the way for human beings to drive the rapid advancement of modern science and technologies. The widespread applications of system theory have made it become the basis for developing new theories in handling complicated system in the fields of politics, economy, military, culture, science, and society, etc. Regarding the trend of system theory, the authors think it is moving towards the formation of unified framework that summarizes the achievements obtained from the empirical and theoretical research in different fields. System thinking ensued by system theory has become a very powerful force to overturn the ingrained singular causation thinking. For ease of studying system, many ways are used to categorize system: (1) natural systems and artificial systems (whether designed by human being or not); (2) natural systems, social systems, and thinking systems (according to research subject); (3) macro systems, mesa system, micro systems, and microscopic systems(scale of the systems); (4) simple systems, complex systems (in term of structure); (5) simple small systems, simple large systems, simple giant systems, and complex giant systems, etc.(scale and structure); (6) open systems, closed systems (whether there exists interaction with environment); (7) balanced systems (systems having equilibrium), non-equilibrium systems, near-equilibrium systems, and far-from-equilibrium systems (whether there exists equilibrium).