The “systems theory” is a set of interdisciplinary contributions that aim to study the characteristics that define systems, that is, entities formed by interrelated and interdependent components.

One of the first contributions to this field was Ludwig von Bertalanffy’s general systems theory . This model has had a great influence on the scientific perspective and continues to be a fundamental reference in the analysis of systems, such as families and other human groups.

Bertalanffy’s systems theory

The German biologist Karl Ludwig von Bertalanffy (1901-1972) proposed in 1928 his general systems theory as a broad tool that could be shared by many different sciences.

This theory contributed to the emergence of a new scientific paradigm based on the interrelationship between the elements that make up systems. Previously it was considered that systems as a whole were equal to the sum of their parts, and that they could be studied from the individual analysis of their components; Bertalanffy questioned such beliefs.

Since its creation, the general theory of systems has been applied to biology, psychology , mathematics, computer science, economics, sociology, politics and other exact and social sciences, especially in the framework of the analysis of interactions.

Defining the systems

For this author the concept of “system” can be defined as a set of elements that interact with each other . These are not necessarily human, or even animal, but can also be computers, neurons or cells, among many other possibilities.

Systems are defined by their structural characteristics, such as the relationship between components, and functional characteristics; for example, in human systems the elements of the system pursue a common purpose. The key aspect of differentiation between systems is whether they are open or closed to the influence of the environment in which they are located.

System types

Bertalanffy and other later authors have defined different types of system based on structural and functional characteristics . Let us see which are the most important classifications.

1. System, subsystem and sub-systems

Systems can be divided according to their level of complexity. The different levels of a system interact with each other, so they are not independent of each other.

If we understand a system as a set of elements, we speak of “subsystems” to refer to such components; for example, a family is a system and each individual in it is a differentiated subsystem . The suprasystem is the environment external to the system, in which it is immersed; in human systems it is identifiable with society.

2. Actuals, ideals and models

Depending on their entitivity, the systems can be classified into real, ideal and model. Real systems are those that exist physically and can be observed , while ideal systems are symbolic constructions derived from thought and language. Models are intended to represent real and ideal characteristics.

3. Natural, artificial and compound

When a system depends exclusively on nature, such as the human body or the galaxies, we refer to them as “natural system”. In contrast, artificial systems are those that arise as a consequence of human action; within this type of system we can find vehicles and companies, among many others.

Composite systems combine natural and artificial elements . Any physical environment modified by people, such as towns and cities, is considered a composite system; of course, the proportion of natural and artificial elements varies in each specific case.

4. Closed and open

For Bertalanffy the basic criterion that defines a system is the degree of interaction with the suprasystem and other systems . Open systems exchange matter, energy and/or information with the surrounding environment, adapting to it and influencing it.

In contrast, closed systems are theoretically isolated from environmental influences; in practice, we speak of closed systems when they are highly structured and feedback is minimal, since no system is completely independent of its suprasystem.

Properties of open systems

Although the properties of closed systems have also been described, those of open systems are more relevant to the social sciences because human groups form open systems. This is the case, for example, in families, organizations and nations.

1. Totality or synergy

According to the principle of synergy, the functioning of the system cannot be understood only from the sum of the elements that compose it , but the interaction between these generates a qualitatively different result.

2. Circular causation or reciprocal co-determination

The action of the different members of a system influences that of the rest, so that the behaviour of none of them is independent of the system as a whole . In addition, there is a tendency to repetition (or redundancy) of the operating patterns.

3. Equifinality

The term “equifinality” refers to the fact that several systems can reach the same end stage even if initially their conditions are different. It is therefore inappropriate to look for a single cause to explain this development.

4. Equity

Equicausality is opposed to equifinality : systems that start out as equals can develop differently depending on the influences they receive and the behaviour of their members. Thus, Bertalanffy considered that when analyzing a system it is necessary to focus on the present situation and not so much on the initial conditions.

5. Stochastic limitation or process

Systems tend to develop certain sequences of operation and interaction between members. When this happens, the probability of different responses from those already consolidated decreases; this is known as “limitation”.

6. Relationship rule

The relationship rules determine which are the priority interactions between the components of the system and which should be avoided. In human groups the relationship rules are usually implicit.

7. Hierarchical arrangement

The principle of hierarchical arrangement applies to both the members of the system and to specific behaviours. It consists of some elements and operations having more weight than others, following a vertical logic.

8. Teleology

The development and adaptation of the system, or teleological process, occurs from the opposition of homeostatic forces (i.e. focused on the maintenance of the current balance and state) and morphogenetic forces (focused on growth and change).