Open Thinkering


TB871: System, variety, recursion in the VSM model

Note: this is a post reflecting on one of the modules of my MSc in Systems Thinking in Practice. You can see all of the related posts in this category

Diagram explaining a Viable System Model for Open University modules, showing connections between learners, the teaching environment, and the recursive levels of educational systems.
Screenshot from an animation show a system, variety, and recursion (The Open University, 2020)

The Viable System Model (VSM) is a powerful conceptual tool for understanding and managing organisations in dynamic environments. It consists of three core concepts: system, variety, and recursion.


In the context of VSM, a system is understood as a purposeful, dynamic structure that processes inputs to produce outputs. Each system is designed to achieve specific goals, which can vary depending on the perspective of the observer. For example, a university can be seen as a system designed to provide higher education, or as a system to train professionals for the workforce. This multiplicity of purposes highlights that different stakeholders can attribute different functions to the same system.

A system is composed of various subsystems, each with its own specific purpose that supports the overall goal of the main system. These subsystems are themselves systems, functioning within the broader context of the primary system’s objectives.


Variety in VSM refers to the range of different states that a system and its environment can adopt. It is a measure of complexity, indicating how many different scenarios the system might need to respond to in order to remain viable. For a system to be viable, it must possess the ability to manage or absorb the variety presented by its environment. This concept is encapsulated in Ashby’s Law of Requisite Variety, which states that only variety can absorb variety.

In practical terms, this means a university must adapt to various demands, such as student needs, regulatory requirements, and market conditions. It must balance the internal processes to meet these diverse external demands effectively.


Recursion in the VSM context refers to the nested nature of systems within systems. This concept, also known as the ‘Russian doll principle,’ implies that the processes and principles governing a system also apply to its subsystems and the larger system it is part of. Each level of the system hierarchy—from the smallest subsystem to the overall metasystem—follows similar organisational principles.

For instance, within a university (the main system), the teaching faculty (a subsystem) is itself composed of various departments (sub-subsystems). Each department operates under the same principles that govern the larger faculty and the university as a whole. This recursive structure ensures that management and operational functions are distributed throughout the system, maintaining coherence and adaptability at all levels.


Leave a Reply

Your email address will not be published. Required fields are marked *