Introduction to Systems Theory (2024)

Assessing an individual’s behavior in relation to the various factors in their life can be a complex process, but social workers can use systems theory to assemble the puzzle pieces. In the context of social work, the application of systems theory allows professionals to look holistically at a client’s conditions and environmental factors to better understand the reasons behind their challenges, hardships, and choices.

Let’s take a deeper look at what systems theory is, how it can be applied to a variety of fields, and how its application to social work is beneficial to both social workers and their clients.

What is systems theory?

Systems theory is an interdisciplinary study of systems as they relate to one another within a larger, more complex system. The key concept of systems theory, regardless of which discipline it’s being applied to, is that the whole is greater than the sum of its parts.

What this means is that when holistically examining how smaller systems come together to affect the greater complex system, certain characteristics of the whole—the complex system—can not be easily explained or rationalized when looking singularly at any one of its systems—its parts.

Systems theory seeks to explain and develop hypotheses around characteristics that arise within complex systems that seemingly could not arise in any single system within the whole. This is referred to as emergent behavior. If a complex system expresses emergent behavior, that means it has characteristics that its properties do not display on their own.

A simple systems theory example is baking. Consider all the ingredients that make up a cake. If you were to lay them out on your counter and weren’t familiar with baked goods, it would be difficult to envision how the eggs, flour, sugar, etc., could be combined and heated to create a cake. That’s because no single ingredient or environmental factor—in this case, heat—would produce a baked good such as cake. From the perspective of systems theory, the whole—our dessert in this example—is greater than the sum of its parts.

Now, imagine you have just baked an item, and you’re unsure of its ingredients. You taste it and it’s sweet, so you can reasonably hypothesize it includes sugar. But what gives it its other qualities? To find out, you’d need to learn the rest of the ingredients and how they were combined to make the final product.

Now, consider the other factors associated with the baked good. Perhaps, it will be served at a celebration, and two people strike up a conversation and further a bond or relationship while enjoying the dessert together. So now, we have a scheduled celebration, flour, sugar, eggs, etc., and ended with two individuals strengthening their relationship—the result of the unique interaction between all these moving parts.

Within any discipline, the application of systems theory involves looking at how all the ingredients (systems) came together to make the cake (complex system/whole) and how this ultimately gave us the end result that none of these properties could produce on their own without a change to their environment (emergent characteristic).

Some fields are extremely diverse in their applications, like social work.

Here are some of the key terms and concepts of systems theory as they apply to psychology, sociology, and social work:

  • System:An entity that’s made up of interrelated/interdependent parts.
  • Complex system:The greater, whole system made up of individual, smaller systems. Generally used in social sciences.
  • Ecological systems:The various systems in an individual’s life that influence their behavior.
  • Homeostasis:The state of steady conditions within a system. A system is always moving toward homeostasis.
  • Adaptation:A system’s tendency to make changes that will protect itself when presented with new environmental factors.
  • Feedback loop:When the outputs of a system ultimately affect its inputs, causing the system to feed back into itself circularly.

History of systems theory

While the idea of the whole being greater than the sum of its parts is not new, the advancement of systems theory lies in the specifics of where and how it is applied. Social work serves as a prime example of the broadened application of this theory.

Beyond social work, systems theory is often applied within various psychological settings and in the physical sciences, such as chemistry and physics.

Modern use of systems theory came about following WWII and the technological advancements of that time. As humans interacted more and more with new technology, researchers needed a more in-depth understanding of human behavior as it relates to the mechanisms around them—machine or otherwise. This is where signal detection theory came from: out of a need to create more effective radar and sonar systems that would ensure military personnel could distinguish between various signals.

The first call for a general systems theory came from Ludwig von Bertalanffy’s research in the 1940s and 1950s. In 1968, he published “General System Theory: Foundations, Development, Applications.” The goal of this book was to outline certain basic laws that can be applied to a wide variety of scientific fields. From his perspective, the cyclical interaction between individual components within a complex system—where each one is both influenced by and causes an effect on the system—can be used to reveal crucial information across various settings. Following this thought process, Bertalanffy reasoned there ought to be universal guidelines or principles that are applied across the sciences and within educational settings to further unify certain fields, specifically the natural and social sciences.

Bertalanffy is considered one of the founders of systems theory as it’s known and applied today. Bertalanffy briefly described systems theory as follows:

“General system theory, therefore, is a general science of wholeness. … The meaning of the somewhat mystical expression, ‘The whole is more than the sum of its parts’ is simply that constitutive characteristics are not explainable from the characteristics of the isolated parts. The characteristics of the complex, therefore, appear as new or emergent.”

— Ludwig von Bertalanffy

Assumptions of systems theory

The main assumption of systems theory is that a complex system is made up of multiple smaller systems, and it is the interactions between these smaller systems that create a complex system.

Systems theory assumes certain underlying concepts and principles can be applied universally in different fields, even if those fields evolved separately. This assumption is a crucial factor in systems theory because it is this reasoning that enables professionals like social workers and psychologists to use systems theory in a way that benefits their clients.

Following that assumption, a general systems theory that provides universal guidelines for scientific research and education will enable further integration and unification of the natural and social sciences. This will yield a better understanding of how these sciences are interrelated and affect our daily lives.

Applications of systems theory

Researchers and other professionals working across various scientific disciplines apply systems theory to extract practical insights. Below are some common examples of careers and fields in which the theory may be used.


Systems psychology is a facet of psychology that examines human behavior and experiences within complex systems. Individuals, communities, populations, and other groups are considered to be systems in homeostasis. For insights into human behavior, systems psychology looks at the greater picture of how these systems and the complex system affect one another.


As an interdisciplinary branch of ecology, systems ecology adopts the holistic approach of systems theory in its examination of ecological systems. It focuses on the interactions between biological and ecological systems.


Similar to other fields that incorporate the principles of systems theory, systems engineering takes on an interdisciplinary approach. Systems engineering, when applied in the real world, often looks like a group effort that encompasses all stages of a product or service, from its creation to its use and disposal.


Taking systems theory all the way down to the molecular level, systems chemistry is one example of the universality of certain scientific principles and assumptions. Scientists in this specialty examine the networks of interacting molecules to create functions from sets of molecules with different emergent properties.

These examples show us that systems theory can offer insights from the molecular level all the way up to examining how one’s environment affects behavior and vice versa.

Now that we’ve looked at some of the common applications of systems theory in different fields, let’s dive deeper into how it can be applied to social work.

How does systems theory apply to social work?

A holistic approach to an individual’s personality, choices, and hardships is crucial for effective social work. Like the other fields mentioned, a social worker must look at all factors that come together in a unique way to shape a client’s identity and experiences.

Social workers may employ systems theory to understand problems like child abuse, family conflict, and community dysfunction as they relate to individuals’ personal issues, such as anxiety, low self-esteem, self-harm, or relationship issues. Drawing on systems theory, experts in the field of social work have developed several practices tailored to their discipline. Below are some common examples.

Family systems theory

Developed by Dr. Murray Bowen in 1946, family systems theory views the family unit as a complex system, containing its own systems and feedback loops. He created eight interlocking concepts of family systems for practitioners to examine and improve family functioning.

The Life Model

The life model of social practice work was developed in 1980 by Carel E. Germain and Alex Gitterman, and was influenced strongly by systems theory. The life model was groundbreaking in that it introduced the idea of bringing the ecological perspective to social work—looking at how singular and complex systems interact with each other as these concepts relate to practicing social work.

The Socio-Ecological Model

The socio-ecological model was developed by Urie Bronfenbrenner in 1979. This model looks at the individual as being conditioned by the five systems that create their environment—individual, micro, meso, exo, and macro. These five systems make up an individual’s current state of affairs from their sex and age at the individual level, to the culture they were raised in at the macro level.

Weaknesses of systems theory

One flaw of social systems theory is that it may not always be sufficient to explain an individual’s current circ*mstances. Examples of this include people who have a severe mental illness that requires unique care or medication. In these cases, a more traditional psychological approach might be used.

Another limitation with social systems theory is that professionals may find it challenging to come up with actionable conclusions based on their findings. Identifying problems is important, but finding solutions to these problems may create difficulty, especially at the cultural and policy levels. Additionally, it may be difficult for social workers to truly understand their clients’ social and cultural upbringing and environment, which may impede progress.

Despite these weaknesses, social systems theory is important to social work and helps practitioners better understand the individuals and populations they serve.

Summary and resources for further learning

Systems theory plays a key role in the advancement of society. Only by looking at all the moving parts can we have a greater understanding of the whole and how it works—a principle that holds true in both physical and social sciences. By applying these broad concepts across disciplines, we can further integrate our understanding of separate phenomena.

As it applies to social science, systems theory is crucial because it looks holistically at the individual to draw insights and use them to take steps forward.

Learn more about Ludwig von Bertalanffy’s research and its significance to systems theory in his work “General System Theory: Foundations, Development, Applications.”

For more information on social ecology and the socio-ecological model, read our article “What is Social Ecology?” (Also explore our guide to important theories in social work.)

To learn more about Bowen’s family systems theory and its eight interlocking components, visit the Bowen Center website.

For more on Alex Gitterman and Carel B. Germain’s work on the life model of social practice work, check out their book titled “The Life Model of Social Work Practice – Advances in Theory and Practice, third edition.”

If you’re interested in a career in social work, explore online social work degrees or discover the journey to becoming a social worker.

Last updated November 2023

Introduction to Systems Theory (2024)
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