Soft systems methodology (SSM) is an approach to organizational process modelling (business process modelling) and it can be used both for general problem solving and in the management of change. It was developed in England by academics at the Lancaster University Systems Department through a ten-year action research program.
The methodology was developed from earlier systems engineering approaches, primarily by Peter Checkland and colleagues such as Brian Wilson. The primary use of SSM is in the analysis of complex situations where there are divergent views about the definition of the problem. These situations are "soft problems" such as: How to improve health services delivery? How to manage disaster planning? When should mentally disordered offenders be diverted from custody? What to do about homelessness amongst young people?
In such situations, even the actual problem to be addressed may not be easy to agree upon.
To intervene in such situations the soft systems approach uses the notion of a "system" as an interrogative device that will enable debate amongst concerned parties. In its 'classic' form the methodology consists of seven steps, with initial appreciation of the problem situation leading to the modelling of several human activity systems that might be thought relevant to the problem situation. By discussions and exploration of these, the decision-makers will arrive at accommodations (or, exceptionally, at consensus) over what kind of changes may be systemically desirable and feasible in the situation. Later explanations of the ideas give a more sophisticated view of this systemic method and give more attention to locating the methodology with respect to its philosophical underpinnings. It is the earlier classical view which is most widely used in practice.
There are several hundred documented examples of the successful use of SSM in many different fields, ranging from ecology, to business and military logistics. It has been adopted by many organizations and incorporated into other approaches: in the 1990s, for example, it was the recommended planning tool for the UK government's SSADM system development methodology.
The general applicability of the approach has led to some criticisms that it is functionalist, non-emancipatory or supports the status quo and existing power structures; this is a claim that users would deny, arguing that the methodology itself can be none of these, it is the user of the methodology that may choose to employ it in such a way.
The methodology has been described in several books and many academic articles.
SSM remains the most widely used and practical application of systems thinking,and other systems approaches such as critical systems thinking have incorporated many of its ideas.
SSM had a gradual development process of the methodology as a whole from 1972 to 1990. During this period of time, four different representations of SSM were designed, becoming more sophisticated and at the same time less structured and broader in scope.
Blocks and arrows (1972)
In the first studies of what became SSM, the methodology is presented as a sequence of stages with iteration back to previous stages. The sequence was: analysis; root definition of relevant systems; conceptualization; comparison and definition of changes; selection of change to implement; design of change and implementation; appraisal.
Seven stages (1981)
In the first book written about SSM, the methodology is presented as a cluster of seven activities in a circular learning process called the seven-stage model. The seven stages are:
Enter situation considered problematical
Express the problem situation
Formulate root definitions of relevant systems of purposeful activity
Build conceptual models of the systems named in the root definitions
Compare models with real-world situations
Define possible changes which are both possible and feasible
Take action to improve the problem situation
Two streams (1988)
The two-stream model of SSM recognizes the crucially important role of history in human affairs. This expression of SSM is presented as an approach embodying not only a logic-based stream of analysis (via activity models) but also a cultural and political stream which enable judgements to be made about the accommodations between conflicting interests which might be reachable by the people concerned and which would enable action to be taken.
Four main activities (1990)
The four-activities model is iconic rather than descriptive and subsumes the cultural stream of analysis in the four activities. The four activities are:
Finding out about a problem situation, including culturally/politically
Formulating some relevant purposeful activity models
Debating the situation, using the models, seeking from that debate both:
changes which would improve the situation and are regarded as both desirable and (culturally) feasible, and
the accommodations between conflicting interests which will enable action
Taking action in the situation to bring about improvement
In 1975, David Smyth, a researcher in Checkland's department, observed that SSM was most successful when the root definition included certain elements. These elements, captured in the mnemonic CATWOE, identified the people, processes and environment that contribute to a situation, issue or problem that required analyzing.
This is used to prompt thinking about what the business is trying to achieve. Business perspectives help the business analyst to consider the impact of any proposed solution on the people involved. There are six elements of CATWOE:
Customers – Who are the beneficiaries of the highest level business process and how does the issue affect them?
Actors – Who is involved in the situation, who will be involved in implementing solutions and what will impact their success?
Transformation process – What is the transformation that lies at the heart of the system - transforming grapes into wine, transforming unsold goods into sold goods, transforming a societal need into a societal need met?
Weltanschauung (or Worldview) – What is the big picture and what are the wider impacts of the issue?
Owner – Who owns the process or situation being investigated and what role will they play in the solution?
Environmental constraints – What are the constraints and limitations that will impact the solution and its success?
Human activity system
A human activity system can be defined as "notional system (i.e. not existing in any tangible form) where human beings are undertaking some activities that achieve some purpose".
^Patching, David (1990). Practical soft systems analysis. London: Pitman. ISBN 0273032372. OCLC 22240151.
Wilson, B. and van Haperen, K. (2015) Soft Systems Thinking, Methodology and the Management of Change (including the history of the systems engineering department at Lancaster University), London: Palgrave MacMillan. ISBN 978-1-137-43268-1.
Checkland, P.B. and J. Scholes (2001) Soft Systems Methodology in Action, in J. Rosenhead and J. Mingers (eds), Rational Analysis for a Problematic World Revisited. Chichester: Wiley
Checkland, P.B. & Poulter, J. (2006) Learning for Action: A short definitive account of Soft Systems Methodology and its use for Practitioners, teachers and Students, Wiley, Chichester. ISBN 0-470-02554-9
Checkland, P.B. Systems Thinking, Systems Practice, John Wiley & Sons Ltd. 1981, 1998. ISBN 0-471-98606-2
Checkland, P.B. and S. Holwell Information, Systems and Information Systems, John Wiley & Sons Ltd. 1998. ISBN 0-471-95820-4
Wilson, B. Systems: Concepts, Methodologies and Applications, John Wiley & Sons Ltd. 1984, 1990. ISBN 0-471-92716-3
Wilson, B. Soft Systems Methodology, John Wiley & Sons Ltd. 2001. ISBN 0-471-89489-3