System Classifications

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In his paper on applying system theory to management science, Boulding (1956) outlined two approaches to system theory:

1.      Definition of common system properties - identification of features common to systems in different disciplines.

2.      Classification of system types – e.g. arrangement of system types into a hierarchy of complexity.


Boulding’s view of system properties was discussed earlier; he also arranged system types in a 9-level complexity hierarchy.

This paper challenges his classification of system, and then challenges whole idea of classifying systems.


A system classification based on system properties. 1

Boulding’s classification of systems. 2

Ackoff’s classification. 3

A classification you might find interesting. 4

Aside on static systems (passive structures) 4

Conclusions and remarks. 4


A system classification based on system properties

An earlier paper concluded with a table that maps system properties (as defined in several sources) to a classification of system types.

A system classification

Discrete entity

Entity that cannot be described as a system

Entity that is disorganised

Entity that (organised or not) cannot be described because it is continually changing

Entity that can be described as a system

System boundary


Cooperating components 

Static system: a passive structure with no behaviour

Dynamic activity system

Orderly or rule-bound behaviour

Naturally-evolved system

does not depend on description by actors

Inorganic natural machine (solar system)

Organic entity (tree or cat)

Natural social organisation

Designed system

depends on description by actors

(symphony, business or software system)

Closed system (as in System Dynamics)

Open system

Input/output exchange across boundary


The table presents socials system as a subtype of dynamic activity systems.

This work makes no assertion about the usefulness of this classification; it is only a vehicle for helping people to appreciate the breadth of system varieties.

Boulding’s classification of systems

Boulding’s view of system properties was discussed earlier.

In the same paper he arranged system types in a 9-level complexity hierarchy, summarised in the table below.

Complexity level

Boulding says (p202 to 205)

Some questions

1 - static structure

The examples given are static descriptions

Does he mean to include also static concrete structures – say buildings?  If not why not?

2 - dynamic system

e.g. clocks and other machines

His dynamics seem limited to motions of matter. What about flows of energy and information? 

3 - control system

e.g. thermostats and other information processing systems

Ashby insists a level 3 control system is much simpler than a level 2 “real machine”

4 - open system

simple life, self-sustaining, self-reproducing, like a cell

Why are other system types not also classified as open?

Surely a cell is a component of classes 5 and 6, rather than a simpler form?

5 - genetic-societal

a plant composed of cells - little or no information processing

What about non-self-aware animals - fleas, ants, fish, worms, bees, oysters?

6 - self-aware animals

image-dependent processing

Is the constructed image different from the constructed state at level 3? Or simply a more complex kind of state?

7 - self-aware humans

whose internal state/memory is complex beyond our reckoning

Surely other apes, all mammals and perhaps other animals belong in this category?

8 - social systems

a system of human roles

Surely a social system of roles is far less complex than a single human? or plant?

9 - transcendental



This so-called complexity hierarchy begs many questions.


Boulding made several interesting points; some clearly have some truth to them; some might be challenged; and some fall into both those categories

He considered the processing of information (including images) to be a significant feature of self-aware systems.

Yet a number plate recognition system is an image-processing information system.

And modern biology regards all life (including plant life) to be a kind of information processing.


Social systems may contain biological actors, does that mean they are more complex?

Boulding confused different kinds of abstraction; he confused complexity level with composition level.

He suggested "in a sense, each level incorporates the levels below it".

But elsewhere he suggested a social system does not contain human beings; it contains only assignments of humans to social roles.


Remember, systems complexity is entirely in the hands of the system describer.

You cannot measure the complexity of an operational system directly - you can only measure the complexity of what appears in your description of that system.

Your description of a tree as a system might be much simpler than a biologist’s description of a single cell a tree leaf.

System theory relies our ability to form abstract system descriptions that hide the internal complexity of component parts.

A higher-level system may be seen as coarse-grained and simple, whereas its lower level components may be seen as complex.

Any higher-level system can contain many lower-level systems whose complexity is completely ignored in the higher level system description.


Surely a social system (at level 8) is far simpler than a human being (at level 7)?

And a control system such as thermostat (at level 3) is simpler than any dynamic system such as a heating system (at level 2) that it controls?


Boulding questioned the adequacy of theoretical models above level 2, and questioned whether there is even rudimentary theory above level 4.

Ackoff’s classification

Ackoff proposed a 4 way classification in which he uses “choice” as the key differentiator between system classes.

Ackoff’s type of System Model




Deterministic (sometimes mechanistic)

No choice

No choice



No choice









No Choice



This classification is also highly questionable, and will be challenged in other paper

A classification you might find interesting

Five overlapping kinds of activity system are tabled below.


A cooperation of

Biological entity

biological organs and cells.

Bio-social organisation

biological entities

Human cognition

brain cells involved in thinking

Human organisation

humans capable of human cognition

Deterministic system

components that execute deterministic processes.


This is not a formal classification; it is only a way to get you thinking about the application of system theory concepts.

Does the term “system” mean the same thing in each domain?

What is the difference between self-sustaining and self-replicating, between organised and self-organising, and between adapting to variety and adapting to novelty?

Aside on static systems (passive structures)

The loosest definition of a system as "a set of interrelated parts" allows that a system may lack any behaviour.

It could be passive hierarchical, lattice or network structure.


·         A description: a map, the Dewey Decimal System.

·         A fence, a bird table, a necklace, stained glass window, a church building, a mountain.

·         A musical score, a computer program listing, a model of a DNA molecule

·         An activity system at rest, a stationary bicycle, or any idle machine.

·         A dead activity system: a log, a corpse, a closed power station.


Bear in mind, you can choose to regard any of these as an activity system if you wish.

A system is what you describe it to be, provided your description is consistent with a recognised theory of what properties a system has in general.


Again, our interest is in activity systems that feature both actors and activities.

Enterprise architects are specifically interested human and computer activity systems (rather than machines such as photocopiers, cars or guns).

Conclusions and remarks

There are many system classifications, and most of them questionable.

Ackoff’s system classification is challenged in another paper.

Boulding’s system classification is challenged above; it is not the scale or continuum he thought it was.

It doesn’t distinguish between operational system (concrete) and system description (abstract).

It doesn’t acknowledge that the complexity of a system at any level depends utterly on abstraction choices made by system describers.

Some of the "levels" might better be considered as "views" of a system.

Each view can be detailed to at any level of abstraction or complexity you choose.


More generally: it is easy to invent classifications of system types, problem types, society types and personality types.

The classification schema may take the form of a simple scale, a hierarchy, a grid, a matrix or other.

People are drawn to schemas that promise to simplify the choices they have to make.

You may be tempted to use a schema to:

·         rewrite world history to match it, build a world view around it

·         help you choose one path or solution option over another

·         decide how people will be organised and/or what roles they play.

·         pigeon-hole somebody and start treating them as a type rather than an individual.


The trouble is – it is difficult to test the validity of schemas as a decision-making tool.

The danger is that a classification scheme can be used to:

·         avoid dealing with problems as individuals

·         avoid taking responsibility for a decision

·         hide personal prejudices behind a superficial rationale.


And since alternative choices are never explored, any or every use may be presented as evidence of the scheme’s validity.



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