Some system thinkers and their ideas

Copyright 2017 Graham Berrisford. One of several hundred papers at Last updated 15/11/2018 19:01


System Theory Tutorial in London Saturday March 2nd 2019


The systems of interest here are islands of orderly behavior in the ever-unfolding process of the universe.

The role of system architects is to observe baseline systems, envisage target systems, and describe both.

So, you might assume architects are taught about system theory and systems thinking; but this is far from the case.


Preface. 1

Classical cybernetics - the science of system control 3

General system theory – the cross-science notion of a system.. 4

System Dynamics – animating a system model to predict long-term outcomes. 5

Soft systems thinking – loosening the system concept 6

Second-order cybernetics – undermining the system concept 7

Conclusions – restoring the system concept 8



Read the science and philosophy of systems thinking for a brief history of the universe.

The discussion there is of how humans came to conceptualise the world in terms of systems.


Read thinkers who foreshadowed system theory for ideas attributed to the thinkers below.

·         Adam Smith (1723 to 1790) subdivision within and competition between systems.

·         Charles Darwin (1809 to 1882) system mutation by reproduction with modification.

·         Claude Bernard (1813 to 1878) homeostatic feedback loops.

·         Herbert Spencer (1820 to 1903) social systems as organic systems.

·         Vilfredo Pareto (1848 – 1923) the Pareto principle.

·         Emile Durkheim (1858-1917) collective consciousness and culture.

·         Gabriel Tarde (1843 –1904) social system as emergent from the actions of individual actors.

·         Max Weber (1864-1920) a bureaucratic model.

·         Kurt Lewin (1890–1947) group dynamics.

·         Talcott Parsons (1902-1979) action theory.


These thinkers may not have spent much time analysing what the word “system” means.

The term may have been used some to mean only "a group of interrelated things".

And not all of their ideas stand the test of time; however, they did influence 20th century systems thinkers.


When “system theory” became established as a topic in its own right is debatable.

Some suggest system theory is a branch of sociology.

“Systems theory, also called social systems theory...

Others suggest the reverse, that social systems thinking is branch of general system theory.

“Though it grew out of organismic biology, general system theory soon branched into most of the humanities.” Laszlo and Krippner.


It is certainly true that the general concept of a system became a focus of attention after second world war.

And there was a burst of systems thinking in the period 1945 to 1980.

Before we review ideas that emerged in that period, here four distinctions to be born in mind.


Actors and activities

David Seidl (2001) said the question is what to treat as the basic elements of a social system.

“The sociological tradition suggests two alternatives: either persons or actions.”

Some see a set of actors who perform activities; others see a set of activities performed by actors.

Actors are structures that exist in space and perform activities.

Activities are behaviors that happen over time, and change the state of the system or something in its environment.

We typify real world actors and activities by defining roles and rules.


Cooperation and conflict between actors

When actors interact in a system, they don’t necessarily help each other.

They may cooperate, as within a football team or a business system.

They may compete, as in a game of chess or a market, or hurt each other, as in a boxing match or a war.

Cooperation, conflict and conflict resolution is a focus of bio-mathematics and game theory.


Abstract and concrete systems (descriptions and realisations)

A theme of this paper is that a social group in the real world is distinct from any abstract social system it realises.

We should describe a system in a way that enables us to test whether a social group instantiates it or not.

In a concrete system: actors perform activities, expected of their roles, to maintain or advance the state of the system or something in its environment.

In an abstract system: roles and rules describe the logic or laws that actors follow in performing activities.

The latter hides the infinite complexity of the actors and activities you may observe in the former


Natural and designed (accidental and purposive) systems

A designed system is often described in terms of aims (motivations), activities (behaviors), actors and objects (structures).

It is created by intent, with aims in mind - though its outcomes may diverge from its aims.

By contrast, a natural system (e.g. the solar system) evolves without any intent.

Some refer to its outcomes (e.g. stable orbits) as its aims, but really they are unintended consequences.

Classical cybernetics - the science of system control

Cybernetics is the science of systems in which biological or mechanical actors process information.

It was established after the second world war (and then soon embraced within a broader system theory movement).


A general idea is a control system receives messages that describe the state of a target system.

The control system responds by sending messages to direct activities in the target system.

Thus, the control and target systems are connected by an information feedback loop.

The information (encoded in messages and memories) describes and/or directs something in the world.


E.g. In a missile guidance system, a control system senses spatial information and sends messages to direct the missile.

A brain holds a model of things in its external environment, which an organism uses to manipulate those things.

A business database holds a model of business entities and events, which people use to monitor and direct those entities and events.

And (as Michael A Jackson taught me in the 1970s) a software system holds a model of entities and events that it monitors and directs in its environment.


The Ratio Club, which met from 1949 to 1958, was founded by neurologist John Bates to discuss cybernetics.

Many of its 21 members went on to become prominent scientists - neurobiologists, engineers, mathematicians and physicists

It members included Ross Ashby and Alan Turing.

In the 1950s, Turing envisaged that computers would give us insights into how the brain works.

In this work. the brain’s abilities are more interesting than its workings.

Systems thinking involves typifying actors using roles, activities using rules, and qualities/values using variables.

The types in systems descriptions range all the way from loosely-defined human roles to rigid software classes and data types.



Roles, Rules & Variables

<create and use>                   <idealise>

Systems thinkers <observe & envisage> Actors, Activities & Values


Let us use the term “entity” for some portion of the universe we are interested in.

If every given entity is a system, then the concept of a system has no value.

In his introduction to cybernetics (1956) Ashby pointed out that every system is an abstraction from the infinite complexity of a given entity.

And moreover, infinite systems can be abstracted from one entity


In cybernetics (and system dynamics below), a system may be characterised as a set of repeatable roles and rules.

When those abstract roles and rules are realised by a concrete entity that repeats behaviors, we have a concrete system.

One abstract system (e.g. the roles and rules of a tennis match) may be realised several times and by several entities in the world.

One entity in the world (the pairing of Federer and Nadal) may realise several systems (several tennis matches and several games of chess).


Ashby not only insisted we distinguish abstract systems from the concrete entities that realise them

He also insisted we distinguish two kinds of system change:

·         System state change by regulation: regulating the values of defined state variables to stay within a desired range.

·         System mutation by re-organization: changing the state variables, or the rules that update variable values.

We’ll return to system mutation later.


Read Introduction to Cybernetics for more on the cybnernetic ideas discussed by these three well-known thinkers.

·         Norbert Wiener (1894-1964) the science of system control.

·         W. Ross Ashby (1903-1972) the law of requisite variety.

·         Alan Turing (1912 –1954) artificial intelligence.

General system theory – the cross-science notion of a system

Bear in mind, system theorists distinguish abstract system descriptions from concrete entities that instantiate (realise) them.

A system description is a complex type; it symbolises both the structures and the behaviors of each entity that realises the system.


General system theory

Abstract / theoretical systems

<create and use>                    <idealise>

System theorists <observe & envisage>  Concrete / empirical systems


The 1954 meeting of the American Association for the Advancement of Science in California was notable.

Four people at that meeting conceived a society for the development of General System Theory.


Ludwig von Bertalanffy (1901-1972) was a biologist who promoted the idea of a general system theory.

His aim was to discover patterns and elucidate principles common to systems in every scientific discipline, at every level of nesting.

He looked for concepts and principles applicable to several disciplines or domains of knowledge rather than to one.

“There exist models, principles, and laws that apply to generalized systems or their subclasses, irrespective of their particular kind.”


Bertalanffy related system theory to communication of information between the parts of a system and across its boundary.

“Another development which is closely connected with system theory is that of… communication.

The general notion in communication theory is that of information.

A second central concept of the theory of communication and control is that of feedback.”

“Every living organism is essentially an open system. It maintains itself in a continuous inflow and outflow…”


So, general system theory incorporates cybernetic concepts such as:

·         System environment: the world outside the system of interest.

·         System boundary: a line (physical or logical) that separates a system from is environment.

·         System interface: a description of inputs and outputs that cross the system boundary.

·         System state: the current structure or variables of a system, which changes over time.


Read Introducing general system theory for more on the ideas of three well-known thinkers who met at that meeting in1954.

·         Ludwig von Bertalanffy (1901-1972) the cross-science notion of a system

·         Kenneth Boulding (1910-1993) applying general system theory to “management science”.

·         Anatol Rapoport (1911 to 2007) game theory and social network analysis.

System Dynamics – animating a system model to predict long-term outcomes

The state of a system is dynamic - it changes over time.

In mathematics, dynamical systems theory and chaos theory deal with the long-term behavior of systems.

The interest is not to predict the next state of the system in response to a single event.

It is rather to answer long-term questions like:

·         "Will the system settle down to a steady state?

·         “What steady states are possible?"

·         “Will the system crash or halt?

·         "Does the long-term behavior of the system depend on its initial condition?"


System dynamics is an approach that reveals the trajectory of quantitative state changes over time.

What makes it different from other approaches is the modelling of feedback loops in flows that increase and decrease the quantities of stocks.

The stocks can be resources of any kind – materials, energy, organisms, happiness, whatever.

System dynamics reveals how feedback loops and time delays affect the stock levels over the long term.


System dynamics is a kind of group dynamics that considers interactions between groups (rather than within a group).

Animating the model reveals the trajectory of changes over time to the size of a group, stock, population or resource quantity.


System Dynamics

Stock and flow models

<create and use>                 <idealise>

System modellers <observe & envisage>  Interdependent quantities


System dynamics may reveal a system behaves in a way that

·         is non-linear - its stocks increase and/or decrease in irregular or chaotic way.

·         settles in a steady state – its variable value(s) settle on fixed value(s).

·         has periodic points – it states repeat over time.


Today, akin to system dynamics, there are agent-based approaches to the analysis of systems.


Read System Dynamics for more on the topic and on the ideas of two well-known system dynamics gurus.

·         Jay Forrester (1918 to 2016) every system is a set of quantities that are related to each other.

·         Donella H. Meadows (1941 to 2001) resource use, environmental conservation and sustainability.

Soft systems thinking – loosening the system concept

Bertalanffy didn’t like some directions in “the System Movement”, especially those specific to one science.

But he saw the movement as “a fertile chaos” that generated many insights and inspirations.

General system theory doesn’t start from or depend on sociology, or analysis of human behavior.

However, it stimulated people to look afresh at social systems in general and business systems in particular.


The term “soft system” emerged in the 1970s; but what does it mean?

And is it really any different from a hard system?

Read Soft Systems for more on ideas of these three well-known soft system thinkers:

·         Peter Checkland (born 1930) the Soft Systems Methodology.

·         Stafford Beer (1926- 2002) management cybernetics and the Viable System Model.

·         Russell L Ackoff (1919-2009) human organisations as purposeful systems.


The main problem with soft systems is the confusion of social entity, group or network with social system.

This confusion is explained and resolved in later papers.

Second-order cybernetics – undermining the system concept

Checkland observed the distinction between hard and soft system approaches is slippery.

The distinction between hard and soft systems is also questionable.

By contrast, the distinction between classical and second-order cybernetics is fundamental.


Remember the distinction made by W Ross Ashby in 1956 between system state change and system mutation?

Second-order cybernetics relates to system mutation by re-organization.

It was developed around 1970 by Margaret Mead, Heinz von Foerster and others.

It is about self-organising systems; it is the recursive application of cybernetics to itself.

It allows systems actors to be system thinkers, who re-organise themselves.

It allows actors in a system to study the system and change it.

Actors not only play roles in a system, but also observe and change the roles, rules and state variables of that system.


Many social system thinkers speak of social groups and businesses as complex adaptive systems.

This undermines the concept of a system, as is shown in the following papers.


There is probably little dispute about these basic ideas about systems.

·         There are forms and functions – actors and activities - in a system.

·         There are accidental and purposive - natural and designed - systems.

·         There are descriptions and realisations - abstract and concrete - systems.


However, much systems thinking discussion has conflated two or more of the following four ideas.

·         People doing their own thing.

·         People communicating with other people.

·         People playing roles in systems.

·         People playing roles in meta systems that administer and manage those systems.


The following papers unscramble ways that these ideas have been confused.


Click here for references and list of systems thinkers.


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