Systems theory emerged in the mid 20th century, drawing on parallel developments in the fields of biology, psychology, management, engineering, information science, and ecology, as well as on a trend toward increasing interdisciplinary collaboration in the social and behavioral sciences. The broad range of perspectives that scholars from these various fields brought to their understanding of systems resulted in an enormous variety of interpretations of systems theory, leading to multiple and often contradictory implications for philosophy and the social sciences.

Ludwig von Bertalanffy (1901–1972) is generally recognized as the father of General Systems Theory, which is one of the key strands in the threads that have been woven into the systems field. He introduced the term in a seminar at the University of Chicago in 1939 to describe an approach to studying the nature of organization in all types of systems. Page 980  |  Top of ArticleA system can be defined as any entity that is composed of parts whose interactions form an integrated whole. It is characterized by a particular structure that constrains the relationships between the elements that constitute the system and a boundary that delineates the system in the context of its environment. Systems can be either open or closed; open systems allow for the exchange of matter, energy, and information with the environment. The elaboration of the concept of open systems was one of Bertalanffy's most important contributions to the development of systems theory.

Bertalanffy believed that all phenomena could be understood as systems and that all systems (physical, biological, and social) displayed common patterns, behaviors, and properties. At the same time, as a theoretical biologist, he also believed that there were properties unique to biological systems that could not be explained according to (or reduced to) purely physical and chemical interactions. Similarly, he argued that human systems (psychological, social, and cultural) could not be explained in purely biological terms. The potential contradiction between these two positions—that all systems contain similar properties and that biological and social systems possess unique characteristics—reflects the underlying tensions between various interpretations of the systems field. In order to understand this tension, and the implications for the application of systems ideas in philosophy and the social sciences, it is helpful to explore the properties that all types of systems share in common, the most significant of which is the idea of self-regulation through feedback.

Another limitation of classical science, according to systems theorists, is its emphasis on linear chains of causality. Developments in the fields of biology, neurophysiology, engineering, and information science highlighted the significance of recursion and self-referentiality in the organization and function of living organisms as well as in the newly emerging technologies. There are several different schools of thought that grew out of different ways of understanding this phenomenon, and different branches of systems theory evolved out of these various formulations.

One of the most influential concepts to come out of the study of biological systems was the notion of homeostasis, which is the ability of living organisms to maintain themselves in a steady state, despite constantly changing internal and external conditions. This ability depends upon a system of communication among the various organs in the body that allows it to maintain constant levels of critical factors such as blood sugar, pH balance, and temperature. If any of these factors deviates from the optimal level, the body is able to respond to restore the balance. The existence of such mechanisms implies a kind of goal-directedness or purposefulness that does not exist in closed systems and depends not only upon the exchange of matter and energy in the system but also on the exchange of information. This organismic model of feedback was central in the development of James Grier Miller's (1916–2002) formulation of systems theory in his massive tome Living Systems Theory, as well as in the development of Talcott Parsons's social system theory.

Miller's work grew out of a decade-long collaboration among scholars from biology, psychology, and the social sciences at the University of Chicago, inspired in part by Bertalanffy's proposal of a general theory of systems. In an effort to articulate similar processes at different levels of organization in living systems, Miller identified 20 different subsystems that processed the input, output, and processing of matter, energy, and information at the level of the cell, organ, organism, group, organization, society, and what he called the supranational system. The concept of organizational levels is another important insight—namely, that living systems, as well as complex technological systems, generally consist of nested systems, with smaller systems existing within the context of larger systems, which are themselves part of systems at an even larger scale of organization.

A parallel development that influenced the community of scholars at the University of Chicago who provided the foundation for Miller's work was a series of conferences sponsored by the Macy Foundation. These conferences, held in the late 1940s and early 1950s, brought together scholars from the social sciences, neurophysiology, and systems engineering, including figures such as Gregory Bateson, Margaret Mead, John von Neumann, and Norbert Wiener. The working title of the conferences, “Feedback Mechanisms and Circular Causality in Biological Page 981  |  Top of Articleand Social Systems,” evolved over the course of the conferences. At one point, the group adopted the term teleological mechanisms, underscoring the potential for purposive activity in biological and even technological systems. Later, they proposed the term cybernetics to characterize the phenomena they were exploring.

Specifically, the participants in these conferences were exploring parallels between neural networks in the brain and recursive operations in the newly emerging field of computer science. This led to a growing emphasis on the role of information and communication in complex systems. In 1929, Leo Szilard had suggested that information was distinct from matter and energy; while the latter can be neither created nor destroyed, information has the potential to increase over time, providing an explanation for the phenomena of evolution and learning in living systems. The cybernetics group sought to understand the mechanisms of information processing, exploring the ways in which information is embedded in the dynamic processes that give rise to complex patterns of organization.

As might be expected, there were significant differences between the orientations of the social scientists and the engineers. Bateson and Mead, in particular, were interested in the unique role of language in the creation of social structure in human communities. In contrast, Weiner emphasized the similarities between organisms and machines. Although his view does not accurately reflect the general orientation of the field as it evolved, his name is perhaps the one most commonly associated with the concept, and the title of his book, Cybernetics: Or Control and Communication in the Animal and the Machine, reflects a mechanistic and reductionist orientation that was not shared by other researchers. Many cybernetics scholars were closely affiliated with the general systems community and tended to focus more on the concept of second-order cybernetics, which emphasized self-referentiality, or the importance of including the observer in the system being observed.

Somewhat distinct from the cybernetics and general systems orientations, system dynamics emerged in the 1950s as another approach to understanding feedback processes. Based on the work of Jay Forrester, system dynamics was rooted in the circuitry models of electrical engineering and emphasized the internal dynamics of organizations rather than the exchange of information in systems. Specifically geared toward applications in management, it tended to focus on the input, processing, and output of material in production processes and to highlight the importance of understanding stocks and flows of materials in such systems. Unlike the models of feedback based on the concept of homeostasis, which only focused on negative feedback (or deviation-minimizing feedback), system dynamics identified both negative and positive (or deviation amplifying) feedback in the dynamics of systems.

While feedback processes can be found in all types of complex systems, some systems thinkers were more concerned with the unique characteristics, or emergent properties, that can be found at higher levels of organization (i.e., biological organisms, human personality structures, and social systems). Bertalanffy's conception of open systems is the foundation for the concept of emergence, which is central to his under-standing of General Systems Theory. According to the second law of thermodynamics, the entropy of any closed system will always increase. Because it takes energy to maintain any kind of organizational structure, the infamous second law implies that all systems will tend toward greater disorder. While this seems to contradict the evidence of evolution, since life has evolved increasingly complex forms over time, Bertalanffy's insight was to suggest that living organisms are open systems and are thus able to import energy from the environment and to export their entropy (or waste), allowing them to maintain complex organizational structures and, more important, to develop increasingly complex structures.

Open systems provide a context in which qualitatively new properties can emerge from the interaction of components within the system, which cannot be predicted or explained based on understanding the components alone. This perspective allows for creative and spontaneous activity in living organisms and suggests that systems at higher levels of organization possess qualities and capacities that do not exist at lower levels. Bertalanffy contrasted his theoretical orientation, which emphasized the self-organizing nature of living systems, with Miller's Page 982  |  Top of Articleorganismic model, which emphasized equilibrium models of feedback and did not allow for the possibility of change. Instead, Bertalanffy argued, living organisms exist in a dynamic steady state, with the potential to adapt to changes in the environment. Ilya Prigogine (1917–2003), the Belgian physical chemist, built on this concept of open systems, suggesting that the further systems are from equilibrium, the greater the potential for more complex forms of organization to emerge. He introduced the concept of bifurcation, which described the tendency, as systems become increasingly unstable, to either reorganize into more complex structures or collapse into less highly ordered structures.

Since its origins in the mid 20th century, systems theory has influenced a broad range of disciplines. Bertalanffy distinguished between three major strands of systems thinking: systems technology, systems science, and systems philosophy. As systems technology, it has been a central framework for the emergence of information technology and systems engineering in general, which has recently launched a new field of study known as “system of systems,” acknowledging the highly interdependent, nested, and networked nature of current technological and organizational systems. As systems science, it articulated a more holistic paradigm for research, influencing recent developments in systems biology, as well as chaos and complexity theories. Although his work originated in the context of theoretical biology, Bertalanffy was particularly concerned with the philosophical and social implications of systems theory and emphasized the holistic and humanistic orientation of General Systems Theory as he conceived it.

The systems perspective offers significant insights into the ontological, epistemological, and ethical dimensions of philosophical inquiry. As ontology, it suggests that phenomena must be understood in terms of whole systems, in contrast to the reductionist and mechanistic orientation of classical science. Echoing insights from the field of quantum mechanics, it emphasizes the interconnected and interdependent nature of reality, proposing a cocreative relationship between the whole and the parts and integrating both upward (from part to whole) and downward (from whole to part) causality. It is process oriented, highlighting the emergence of organization out of the dynamic patterns of relationship between the components of a system.

The various traditions of systems thinking offer a variety of interpretations of the epistemological implications. Reflecting further parallels with emerging understandings from quantum mechanics, some schools of systems thought highlight the active role of the observer in the system being observed, leading them to embrace a constructivist epistemology. Other schools of thought, such as Miller's living system orientation and the system dynamics tradition, embody a more objectivist epistemology. Nevertheless, most systems thinkers emphasize the importance of integrating multiple perspectives in understanding any system, arguing that no single lens can provide a comprehensive and accurate representation. In addition to the implications of this orientation for education, there are significant ethical consequences that inform contemporary applications of systems thinking in social organizations. Proponents of this view consider an ethic of inclusiveness and collaboration to be essential in the application of systems thinking in the social context.

The concept of emergence is central in understanding the implications of systems thinking in the social sciences. It informed Bertalanffy's views on psychology, which had a significant impact on the evolution of the fields of humanistic psychology and family systems theory. He was particularly opposed to the behaviorist model of stimulus and response as the primary motive forces in human behavior, which he saw as a reductionist approach rooted in a homeostatic model. Instead, he saw human consciousness as an emergent property characterized by self-reflective awareness, highlighting the importance of considering the role of subjectivity and autonomy in understanding humans as active agents. At the same time, he rejected the individualistic conception of identity and motivation, which conceived individuals as separate from the entire web of relations in which they are embedded.

In contrast to Bertalanffy's view, some systems models, paralleling structural and functionalist schools of thought, tend to minimize the autonomy Page 983  |  Top of Articleof the individual, emphasizing instead the structure of the social system as a whole. This orientation can be traced back to Herbert Spencer's organismic understanding of the social order and is reflected to some extent in Miller's living systems model and Talcott Parsons's social systems theory, both of which were rooted in organismic models that tended to emphasize homeostasis. Parsons's theory of social action described the interrelationships between organism, personality, culture, and society, portraying society as an autonomous system with the goal of maintaining stability, order, cooperation, and consensus through the communication of values and cultural norms. As a result, it tended to downplay the autonomy of the individual, and critics argued that the model ignored the role of conflict, did not adequately account for change, and tended to rein-force the status quo.

Building on Parsons's model, Niklas Luhmann is the most well-known contemporary social systems theorist, whose work is further informed by the conceptual framework developed by Humberto Maturana and Francisco Varela. They coined the term autopoiesis to refer to the process of self-creation or self-production in living systems. Although echoing earlier work on the concept of self-organizing systems, they argued that the organization of a system could not be changed without destroying the integrity of the system. In their view, living systems were closed in terms of their internal organization but open in terms of their structural composition and metabolism, reproducing themselves through a process of structural coupling with their environment. Based on this understanding, Luhmann conceived of society as an autopoietic system of communication. Like Parsons's model, this conception tended to privilege the social system as a whole over the autonomy of its individual members.

In his work on the role of communication in society, Jürgen Habermas voiced concerns that many scholars shared about the eclipse of subjectivity—or what he called the lifeworld—in systems models, and he engaged Luhmann in an ongoing debate about the relative significance of life-world and system concerns. While both addressed the source of meaning and motivation in human behavior, Habermas argued that Luhmann placed too much emphasis on the structure-maintaining role of the autopoietic social structure, emphasizing instead the generation of the social world through the evolving process of discourse. Habermas's critique was particularly influential in the application of systems thinking in social organizations.

While systems thinking has informed the evolution of disciplines across the spectrum, it has perhaps had the most influence in the applied social sciences. Beginning in the 1940s and 1950s as systems engineering, systems analysis, or operations research, it embodied a positivistic orientation, using systems principles to maximize performance in socio-technical systems. These approaches, which were characterized by top-down decision making and control, later became known as hard systems methodologies, in contrast to the soft systems approaches that emerged in the 1970s and 1980s, which sought to integrate the experiential, subjective (or life-world) dimension of organizational systems.

Soft systems approaches emphasized the active inclusion of all parts of the system in the decision-making process, recognizing not only the goal-seeking but also the relationship-maintaining function of organizations and embodying a shift in emphasis from structure to process. A critical insight to emerge from the soft systems orientation, reflecting the interpretive orientations in the social sciences, is the importance of surfacing the various beliefs, assumptions, and frames of reference—or mental models—that members of organizations bring to their participation. This has resulted in the understanding of organizations as learning systems, highlighting the potential for the emergence of new forms of social organization. More recent developments in applied systems thinking, described as critical or emancipatory systems approaches, suggest that soft systems approaches have failed to address underlying issues of power, privilege, and domination, with the ultimate goal of facilitating the design of human systems that effectively serve the whole system, while acknowledging the integrity and autonomy of the individual.