Checkland and Soft Systems

Copyright 2017 Graham Berrisford. One of several hundred papers at Last updated 03/11/2018 18:02


What does “soft” mean? And is a soft system any different from a hard system?


The triumvirate who created the soft systems methodology. 1

Checkland’s soft system methodology. 2

Checkland’s system.. 2

Checkland’s conceptual model 3

Checkland’s root definitions and CATWOE.. 3

Checkland’s methodology. 4

Checkland’s design pattern. 5

Soft?. 5

Soft meaning 1: a system that is theoretical, a perspective of a concrete reality. 5

Soft meaning 2: a system with questionable aims. 5

Soft meaning 3: a human situation rather than a system.. 6

Soft meaning 4: a methodology rather than a system.. 6

Soft meaning 5: a meta system.. 6

Soft meaning 6: a socio-technical system.. 6

Conclusions and remarks. 7


The triumvirate who created the soft systems methodology

Bausch (2001) alludes to Churchman, Ackoff and Checkland as the triumvirate who created the “soft systems methodology” in the 1970s.

Churchman initially wrote for people in what was then called the operations research department.

Operational researchers studied regular business operations and proposed how to optimise systems they found therein.


Churchman’s view

Business systems

<define and optimise>                <abstracted from>

Operations research <observe and envisage> Business operations


Ackoff said many things, not all of them made sense.

In “System of System Concepts” (1971), Ackoff’s first, his first four ideas about systems were these:

1.      System: a set of interrelated elements

2.      Abstract system: a system in which the elements are concepts.

3.      Concrete system: a system that has two or more objects that act to realise an abstract system.

4.      System state: the values of a system’s properties at a particular time.


Ackoff’s v iew

Abstract systems

<create and use>                   <idealise>

Observers <observe & envisage> Concrete systems


The property values of a concrete system realise the property types or variables in an abstract system description.

The concrete entity we call IBM can and does realise many different abstract systems, and is therefore many concrete systems at once.

Can the IBM be a system before we describe that system? Yes and no.

It can be infinite systems before we describe any of them.

But it is meaningless to say IBM is a system without reference to which of those infinite system descriptions we have in mind.


Peter Checkland spoke of systems as input-to-output transformations.

He defined a system as a perspective of a reality, a world view or “Weltenshauung”.


Checkland’s view


<define>            <are views of>

Stakeholders  <observe and envisage>  The world

Checkland’s soft system methodology

Ashby said infinite theoretical/abstract systems may be abstracted from any empirical/concrete entity.

Checkland brought this idea into his methodology.

Checkland’s system

Checkland defined a system as a perspective of a reality, a world view or “Weltenshauung”.

“Implicit here is the notion that an observer engaged in systems research will give an account of the world, or part of it, in systems terms;

·         his purpose in so doing;

·         his definition of his system or systems;

·         the principle which makes them coherent entities;

·         the means and mechanisms by which they tend to maintain their integrity;

·         their boundaries, inputs, outputs, and components;

·         their structure.” Checkland (1981, p. 102.)


To paraphrase, Checkland’s system (aka transformation) might be defined thus.

·         A structure of components

·         that interact in mechanisms that

·         maintain the integrity/coherence of the entity and

·         consume/deliver inputs/outputs

·         from/to each other and external entities.


The table below shows Checklans system concept is much the same as in hard system thinking approaches.


Generic system description

Ashby’s design for a brain

Boulding’s social system

Checkland’s Soft System (Transformation)

An object-oriented software system

A collection of active structures

that interact in regular behaviors

that maintain system state and/or

consume/deliver inputs/outputs

from/to the wider environment.

A collection of brain cells that

interact in processes to

maintain body state variables by

receiving/sending information

from/to bodily sensors/motors.

A population of individuals that interact by

processing information in the light of

mental images they remember, and

exchange messages to communicate meanings

to others and related populations.

A coherent entity, a structure of components

that interact in mechanisms that

maintain the integrity of the entity and

consume/deliver inputs/outputs

from/to each other and external entities.

A population of objects that interact by

processing information in the light of

state data they remember, and

exchange messages to communicate

with other objects and system users.


All four specific cases fit the generic system description reasonably well.

In every case, the real world entity is regarded as a system only in so far as it realises a system description.

Checkland’s conceptual model

Checkland proposed modelling the transformation (the system) in an abstract and informal “conceptual model” or “business activity diagram”.

This model shows transformation activities connected by dependency arrows.

Checkland’s root definitions and CATWOE

Checkland proposed drawing up root definitions of a business entity – to uncover different viewpoints

E.g. Who is the customer of the system that distributes money from various European Union agricultural schemes to French farmers?

The farmers? The French government? The French taxpayer? The European agency whose existence depends on the scheme?


This source offers this example root definition.

“A company owned system to market the products and services of the company to existing and future clients by the most appropriate cost effective means.”

Then analyses that root definition using Checkland’s CATWOE acronym as below.

The “system” is primarily the Transformation, and the roles of Actors in that.


Root definition analysis



Entities that receive outputs from the transformation

“existing and future clients”



Entities that do or could perform activities in the transformation

“the company”



Activities that transform input to outputs

“Market the products and services of the company”


World view

The belief that makes sense of the root definition

Providing appropriate marketing to a particular client will promote company products and services



The decision maker concerned with system performance

“the company”



Constraints outside the system significant to the system

“appropriate cost effective means”


A truly general system theory (think, the solar system) does not feature Customers or Owners.

And for business systems, CATWOE may underplay the importance of Objectives, Outputs, Inputs and Suppliers.

Checkland’s methodology

Checkland Soft Systems Methodology (SSM) has seven main steps

This can be presented as a variation of the approaches used in hard systems engineering.

The table below compares the seven steps of SSM with the steps in a typical system engineering methodology.

The difference are mostly cosmetic, a matter of emphasis or of particular technique.


A system engineering methodology

Checkland’s Soft Systems Methodology

Study the context: goals, constraints, stakeholders, their concerns, problems and requirements

1.       Enter the problem situation.

Outline optional solution visions, along with value propositions for stakeholders

2.       Express the problem situation (a rich picture)

Analyse trade offs between solution options with respect to the context

3.       Formulate root definitions of relevant systems (validated using the CATWOE analysis below)

Describe a target system that compromises between conflicting goals and constraints

4.       Represent human activity systems as conceptual models (business activity models)

Plan the work to move from the current to the target system

5.       Compare the models with the real world.

Follow the plan to build and test the target system

6.       Define changes that are desirable and feasible

Roll out the target system.

7.       Take action to improve the real world situation.


This table shows both soft systems analysts and mechanical engineers are taught much the same process.

Even mechanical engineers have to trade off between different goals, some of which conflict.

The fact that stakeholders approve a target system description doesn’t mean they share the same perspective of, or purpose for, the system.

Each stakeholder may have their own perspective of and value proposition for a motor car.

Checkland’s design pattern

Checkland proposed a generic design pattern for structuring a business.

First, regular operations management: a control system to set aims for, monitor and direct the transformation activities.

·         Defining targets for operations

·         Operations (the transformation or business system)

·         Monitoring and Controlling Operations (the regulatory system).

Second, overarching executive/governance: a meta system to set aims for, monitor and control the regular operations management.


What does “soft” mean? And is a soft system any different from a hard system?

Soft meaning 1: a system that is theoretical, a perspective of a concrete reality

Peter Checkland (like Ashby) spoke of systems as input-to-output transformations.

He defined a soft system as a perspective of a reality, a world view or “Weltenshauung”.

The difficulty here is that “hard systems” thinkers make the same point.

W Ross Ashby wrote that infinite theoretical systems may be abstracted from a concrete entity or “real machine”.

If all systems are abstractions, how else to distinguish soft systems from hard systems?

Soft meaning 2: a system with questionable aims

“Churchman, Ackoff and Checkland consider hard systems methodology to be a special application of systems theory in situations where the objectives are not in question” Bausch (2001)

By implication, the distinguishing feature of a soft system is a debate about its aims.

However, the objectives of human beings, businesses, and even man-made things like motor cars, are questionable.

Which is why even mechanical engineers are taught to manage stakeholders and trade off between conflicting goals.

Soft meaning 3: a human situation rather than a system

Checkland proposed his Soft Systems Methodology starts not with spotting a system to be reengineered but with spotting a confusing or complex situation.

OK, but these are not mutually exclusive starting points – and the end product is indeed a re-engineered human activity system.

His concern is to model regular business systems (he called transformations), and change them from a baseline (problematic) state to a target (improved) state.

Soft meaning 4: a methodology rather than a system

After several decades, Checkland wrote "Soft Systems Methodology: A Thirty Year Retrospective" (2000)

In his review, he said the hard-soft distinction had proved slippery; people grasp it one week and lose it the next.

He said the term "soft" was intended to describe not systems, but an approach to solving problems in human activity systems.

OK, but defining a systems thinking approach as soft is very different from defining a system as soft.

Soft meaning 5: a meta system

Checkland said he designed the Soft Systems Methodology as a “learning system”.

OK, but all traditional system design methodologies include activities intended to help designers learn about the context.

And it is important not to confuse the meta system with the system.


Classical system theory can be applied to a human system (some call this “structuralism”).

Consider a tennis match as a system.

The human actors play defined roles, follow defined rules, and communicate using agreed terms (“fault”, “second serve”, etc).

If the players stop to debate and change the rules of the tennis match they are playing in, they are acting outside that system.

They are now playing roles in a meta system that observes and changes the system.

Soft meaning 6: a socio-technical system

In practice, it may be clearer to think of soft systems thinking as subtype of hard systems thinking, which is specific to:

·         Open (rather than closed) systems, which have external customers and suppliers.

·         Designed and purposive (rather than naturally evolved) systems, which have owners and stakeholders.

·         Social and socio-technical (rather than purely technical) systems, which employ human actors.


A socio-technical system is typically defined as “a group of people organised to use technologies to realise the functions of a system.”

But this is to flip between a discussing a concrete social group and an abstract system it realises.

·         An abstract business system comprises logical functions that produce and consume data flows, and roles that people can play.

·         A concrete business comprises real organisation units that realise the functions, and actors who realise the roles.


A business employee is only a member of the abstract system where/when they realise one or more roles in it.

And every person does many things outside of the abstract system.

There is rarely much that is sociological (political, cultural or personal) in models of a socio-technical system.

Except, perhaps, the risk that a data flow is inadequate or not understood, which might be addressed by adding a data flow to request clarification.

Conclusions and remarks

The biggest single issue in soft systems thinking is the confusion between:

·         A social group or network in which people communicate

·         A social system in which people realise role and rules.


It is social network (not the social system) that has self-organizing dynamics.

It is strongly recommend that you now read Social networks versus social systems.



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