Tag Archives: epistemology

Modelling HPM as a PSM, using HPM

I conclude my book on Problem Structuring with some comments on a processual turn in Operational Research (Yearworth, 2025) and specifically comment

“In modelling the world processually we can also model our interventions within the same model … Or put more simply, problematic situations are processes as are the means of intervention.” (p. 270). 

Modelling our interventions specifically requires the possibility of representing our use of a problem structuring method as a model. Checkland and Poulter described the process of using Soft Systems Methodology (SSM) in the activity system ‘language’ of SSM itself (Checkland & Poulter, 2006, p. 194; Yearworth, 2025, p. 78). Checkland and Scholes went further and modelled the system to use SSM in the same purposeful activity system language i.e., the ongoing reflective practice of using SSM in client engagements (Checkland & Scholes, 1990, p. 294).  

The same approach has been used for describing the use of Hierarchical Process Models (HPM) for problem structuring. This was first manifest in the STEEP Project as means of self-evaluation of how well the methodology was performing, making use of the Italian Flag as a means of capturing judgement of process performance (Yearworth et al., 2015, p. 9). In the Healthy Resilient Cities project (Yearworth, 2015), we started to model the process of using the PSM within the model of the problematic situation itself (Yearworth, 2025, p. 173) i.e., the process <Improving the resilience of healthcare provisioning in Bristol…> contained within it the process <Using problem structuring>. Further work on exploiting the Italian Flag for capturing judgements of process performance in the use of a PSM was explored in depth by Lowe, Espinosa and Yearworth (2020).

The development of HPM as a PSM is described fully in Chapters 9 and 10 of my book. However, the work of modelling HPM as a PSM using HPM itself that was started in the STEEP project is still ongoing. The following shows its current incarnation in Strategyfinder.

HPM of using HPM as a PSM

Note that methodological learning, an essential element of using a PSM, is reflected in the model at Process #26 <Evaluating the engagement and improving our understanding …> and the processes it contains. The model also references other models that could be incorporated as enhancements, for example using the framework for improving facilitation developed by Ackermann (1996, p. 95), which has been interpreted in my book as another process model (Yearworth, 2025, p. 108). This illustrates the property that all HPM are composable according to their necessity and sufficiency for the success of the process that acts as the anchor for incorporation.

Ackermann, F. (1996). Participants’ perceptions on the role of facilitators using group decision support systems. Group Decision and Negotiation, 5(1), 93-112. https://doi.org/10.1007/BF02404178

Checkland, P., & Poulter, J. (2006). Learning for action : a short definitive account of soft systems methodology, and its use for practitioner, teachers and students. John Wiley & Sons: Chichester. 

Checkland, P., & Scholes, J. (1990). Soft systems methodology in action. John Wiley & Sons: Chichester. 

Lowe, D., Espinosa, A., & Yearworth, M. (2020). Constitutive rules for guiding the use of the viable system model: Reflections on practice. European Journal of Operational Research, 287(3), 1014-1035. https://doi.org/10.1016/j.ejor.2020.05.030

Yearworth, M. (2015). Healthy Resilient Cities: Building a Business Case for Adaption (NERC NE/N007638/1)[Grant]. Bristol. http://gotw.nerc.ac.uk/list_full.asp?pcode=NE%2FN007638%2F1

Yearworth, M. (2025). Problem Structuring: Methodology in Practice (1st ed.). John Wiley & Sons, Inc.: Hoboken. https://doi.org/10.1002/9781119744856

Yearworth, M., Schien, D., Burger, K., Shabajee, P., & Freeman, R. (2015). STEEP Project Deliverable D2.1(R2) – Energy Master Plan Process Modelling. STEEP PROJECT (314277) – Systems Thinking for Comprehensive City Efficient Energy Planning, pp78. Retrieved 26th January 2023, from https://www.grounded.systems/wp-content/uploads/2023/01/01_STEEP_D2.1_Energy_Master_Plan_process_model_update_M24_DEF_sent.pdf

Problem Structuring : Methodology in Practice

My new book is now available!

Current perspectives on approaches to problem structuring in operational research and engineering and prospects for problem structuring methods applicable to a wide range of practice.

Despite the myriad successes of Operational Research (OR) in government and industry, critique of its continued relevance to complex, wicked problems led to the emergence and evolution of Soft OR as a more humanist orientation of the discipline centred on a methodological framing of techniques known as Problem Structuring Methods (PSMs). These have enabled OR practitioners to broaden the scope of OR to address complex problem contexts that require transforming, planning and strategising interventions for their clients. The original core PSMs of Soft Systems Methodology (SSM), Strategic Options Development and Analysis (SODA) and the Strategic Choice Approach (SCA) are presented using a new analytical framework based on constitutive rules, epistemologies, and affordances of the modelling approach. Practical considerations in PSM based interventions are discussed emphasising trust-building, stakeholder identification, facilitation and ethical practice. A wide range of PSM applications are surveyed demonstrating clear intersections with communities of practice grounded in the applied social sciences. The development of a new PSM based on Hierarchical Process Modelling (HPM) of purpose arising from a processual turn in engineering practice offers additional insights for the practice of Soft OR. New developments in PSM practice built on use of Group Support Systems (GSS) and exploiting developments in machine learning are presented. Prospects for bringing the Soft OR project back into better alignment with mainstream OR are discussed in the context of new education programs and a possible processual turn in OR.

Problem Structuring: Methodology in Practice contains four linked sections that cover:

  1. Problem formulation when dealing with wicked problems, justification for a methodological approach, the emergence of soft OR, the relevance of pragmatic philosophy to OR practice.  
  2. Traces debates and issues in OR leading to the emergence of soft OR, comparative analysis of PSMs leading to a generic framework for soft OR practice, addressing practical considerations in delivering PSM interventions.
  3. Charts the emergence of a problem structuring sensibility in engineering practice, introduces a new PSM based on hierarchical process modelling (HPM) supported by teaching and case studies, makes the case for a processual turn in engineering practice supported by HPM with relevance to OR practice.
  4. Evaluation of PSM interventions, survey of applications, use of group support systems, new developments supported by machine learning, re-contextualising soft OR practice.

Problem Structuring: Methodology in Practice is a thought-provoking and highly valuable resource relevant to all “students of problems.” It is suitable for any UK Level 7 (or equivalent) programme in OR, engineering, or applied social science where a reflective, methodological approach to dealing with wicked problems is an essential requirement for practice.

Note that some institutions may have access via their usual eBook provider (e.g. ProQuest, Perlego), if not by default on the subscription then by a separate order for this specific title.

A PSM Reading List

  • Ackermann, F., & Eden, C. (2011). Making strategy: mapping out strategic success (2nd ed.). Sage: London.
  • Baert, P. (2005). Philosophy of the social sciences : towards pragmatism. Polity: Cambridge.
  • Callon, M., Lascoumes, P., & Barthe, Y. (2009). Acting in an uncertain world : an essay on technicaldemocracy. MIT: Cambridge, Mass.
  • Checkland, P. (1999). Systems thinking, systems practice: Includes a 30-year retrospective. John Wiley & Sons: Chichester.
  • Checkland, P., & Poulter, J. (2006). Learning for action : a short definitive account of soft systems methodology,and its use for practitioner, teachers and students. John Wiley & Sons: Chichester.
  • Checkland, P., & Scholes, J. (1999). Soft Systems Methodology in Action: Including a 30-year retrospective. John Wiley & Sons: Chichester.
  • Conklin, J. (2006). Dialogue mapping : building shared understanding of wicked problems. John Wiley & Sons: Chichester.
  • Eden, C., Jones, S., & Sims, D. (1983). Messing about in problems : an informal structured approach to their identification and management. Pergamon: Oxford.
  • Friend, J., & Hickling, A. (2005). Planning under pressure : the strategic choice approach (3rd ed.). Elsevier Butterworth-Heinemann: Oxford.
  • Keys, P. (Ed.). (1995). Understanding the process of operational research : collected readings. John Wiley & Sons: Chichester.
  • Kilgour, D. M., & Eden, C. (Eds.). (2020). Handbook of Group Decision and Negotiation. Springer International Publishing: Cham. doi:10.1007/978-3-030-12051-1
  • Morecroft, J. (2007). Strategic modelling and business dynamics : a feedback systems approach. John Wiley & Sons: Chichester.
  • Pidd, M. (Ed.). (2004). Systems modelling : theory and practice. John Wiley & Sons: Chichester.
  • Pidd, M. (2009). Tools for thinking : modelling in management science (3rd ed.). John Wiley & Sons: Chichester.
  • Rosenhead, J. (Ed.). (1989). Rational analysis for a problematic world : problem structuring methods for complexity, uncertainty and conflict. John Wiley & Sons: Chichester.
  • Rosenhead, J., & Mingers, J. (Eds.). (2001). Rational analysis for a problematic world revisited : problem structuring methods for complexity, uncertainty and conflict (2nd ed.). John Wiley & Sons: Chichester.
  • Salhi, S., & Boylan, J. (Eds.). (2022). The Palgrave Handbook of Operations Research. Palgrave Macmillan Cham. doi:10.1007/978-3-030-96935-6.
  • Senge, P. M. (1990). The Fifth Discipline: The Art and Practice of the Learning Organization. Random House: London.
  • Vennix, J. (1996). Group Model Building: Facilitating Team Learning Using System Dynamics. John Wiley & Sons: Chichester.
  • Yearworth, M. (2024). Problem Structuring : Methodology in Practice. John Wiley & Sons: Chichester.

Wicked problems and category mistakes

Wicked problems and category mistakes

This is a brief introduction to the notion of a wicked problem. It is based on the highly-cited paper by Rittel and Webber (1973). The following characterise wicked problems:

  1. There is no definitive formulation. In a sense, formulating a wicked problem is the problem
  2. There are no stopping rules. The process of intervening is also the same as understanding the nature of the problem – the intervention is “good enough” or the best that can be achieved within other limitations (e.g. of time, budget…)
  3. Interventions are not right or wrong, they can only be viewed as making things better or worse for certain interests i.e. the intervention has made things both better and worse depending on who you ask
  4. There is no immediate or ultimate test of an intervention. Interventions will generate “waves of consequences” over a period of time
  5. Interventions are “one-shot operations”, experiments are difficult to conduct, every intervention counts significantly, they are essentially unique in nature
  6. No enumerable, exhaustively describable, set of possible interventions
  7. Every wicked problem is essentially unique. “Essentially” implies that aspects may be common, but to think in terms of categories or “classes” of wicked problems with common “solutions” is misleading
  8. Wicked problems can be considered as symptoms of other problems i.e. there is inherent systemicity in the world
  9. Can be contested at the level of explanation, there is likely to be conflicting evidence or data

The corollary of this definition is that certain statements about problems are likely to be rendered false or meaningless if it can be shown that the problem is actually wicked, in effect the statement is demonstrating that a category mistake is being made. The following is not an exhaustive list:

  1. ‘Solving’ or ‘curing’ a wicked problem is a contradiction; there are no ‘solutions’, ‘cures’…
  2. Words that suggest an objective point of view used in the context of the problem at the very least need to be debated e.g. words like optimal, best, right, smart, correct, … all suggest the question – for whom? Alternatively, no decision taken should ever be considered wrong.
  3. Any statement of measurable quantity that supports an argument for the problem getting better or worse without acknowledging the dynamic complexity that systemicity implies i.e. “…worse then better…” is a more believable statement given dynamic complexity
  4. Statements that appear to deny the systemic nature of the problem e.g. ignoring requisite variety
  5. Containing irrefutable assertions of fact e.g. “…this proves conclusively that…”
  6. Use of binary choices, any mention of “silver bullets”
  7. Misrepresenting or ignoring plurality e.g. “The public…”
  8. Emphasis on producing plans rather planning as a process

If any of these corollaries are contested e.g. if someone claims to have a solution to a wicked problem, then they are likely to be making a claim about only an aspect of the problem, or only from a certain viewpoint; or their formulation is not that of a wicked problem i.e. they are talking about something ‘tame’. Statements that contain phrases like “…optimal solution…” or “…this proves conclusively that if we do this we will have the best outcome…” in the context of a wicked problem definitely signal a likely category mistake.

Category mistakes are a warning sign – be sceptical of claims being made. They suggest either misunderstanding or partiality.

It’s worth reading the Rittel and Webber paper. Despite its age, it still does an exceptionally good job of reminding us of the characteristics of wicked problems that’s just as relevant today.

The first steps towards a coherent approach to problem formulation can be found in Rosenhead’s (1996) introduction to Problem Structuring Methods.

Rittel, H. W. J., & Webber, M. M. (1973). Dilemmas in a general theory of planning. Policy Sciences, 4(2), 155-169. doi:10.1007/BF01405730
Rosenhead, J. (1996). What’s the problem? An introduction to problem structuring methods. Interfaces, 26(6), 117-131. doi:10.1287/inte.26.6.117

A Systems Reading List

I often get asked to recommend books on systems thinking, systemic problem structuring, and systems modelling – from general introductions to specialist texts. In this update I have reduced the list to a more manageable length and split it into two parts – essential and further reading. Note that I recommend the 1999 versions of ‘Systems thinking, systems practice‘ and ‘Soft Systems Methodology in Action’ since they both include Checkland’s excellent reflections on 30-years’ of Soft Systems Methodology (SSM). If you are learning about and using SSM then I think you also need to know something about Strategic Options Development and Analysis (SODA)/JourneyMaking and the Strategic Choice Approach (SCA).

Essential Reading

  • Ackermann, F., & Eden, C. (2011). Making strategy : mapping out strategic success (2nd ed) London: Sage.
  • Beer, S. (1985). Diagnosing the system. Chichester: John Wiley & Sons Ltd.
  • Checkland, P. (1999). Systems thinking, systems practice: Including a 30-year retrospective. Chichester: John Wiley & Sons Ltd.
  • Checkland, P., & Poulter, J. (2006). Learning for action : a short definitive account of soft systems methodology, and its use for practitioner, teachers and students. Chichester: John Wiley & Sons Ltd.
  • Checkland, P., & Scholes, J. (1999). Soft Systems Methodology in Action: Including a 30-year retrospective. Chichester: John Wiley & Sons Ltd.
  • Jackson, M.C. (2019). Critical Systems Thinking and the Management of Complexity. Chichester: Wiley-Blackwell.
  • Midgley, G. (2000). Systemic intervention : philosophy, methodology, and practice. New York: Kluwer Academic/Plenum.
  • Mingers, J., & Rosenhead, J. (eds) (2001). Rational analysis for a problematic world revisited : problem structuring methods for complexity, uncertainty and conflict (2nd ed). Chichester: John Wiley & Sons Ltd.
  • Pidd, M. (2004). Systems modelling : theory and practice. Chichester: Chichester: John Wiley & Sons Ltd.
  • Pidd, M. (2010). Tools for thinking : modelling in management science (3rd ed). Chichester: John Wiley & Sons Ltd.
  • Sterman, J.D. (2000). Business dynamics : systems thinking and modeling for a complex world. Boston, Mass.: Irwin McGraw-Hill.
  • Vennix, J. (1996). Group Model Building: Facilitating Team Learning Using System Dynamics. Chichester: John Wiley & Sons Ltd.

Further Reading

  • Ackoff, R.L., & Emery, F.E. (1972). On purposeful systems. London: Tavistock Publications.
  • Coyle, R.G. (2004). Practical strategy : structured tools and techniques. Harlow: Financial Times Prentice Hall.
  • Friend, J.K., & Hickling, A. (2005). Planning under pressure: the strategic choice approach (3rd ed). Oxford: Elsevier Butterworth-Heinemann.
  • Jackson, M.C. (2003). Systems thinking: creative holism for managers. Chichester: John Wiley & Sons Ltd.
  • Midgley, G., & Ochoa-Arias, A. (2004). Community operational research : OR and systems thinking for community development. New York ; London: Kluwer Academic/Plenum.
  • Morecroft, J.D.W. (2007). Strategic modelling and business dynamics : a feedback systems approach. Hoboken, N.J.: Wiley
  • Ramage, M., & Shipp, K. (2009). Systems Thinkers. London: Springer.
  • Richardson, G.P. (1991). Feedback thought in social science and systems theory. Philadelphia: University of Pennsylvania Press.
  • Senge, P.M. (1990). The Fifth Discipline: The Art and Practice of the Learning Organization. London: Random House.

Hard Systems and Soft Systems

Hard Systems and Soft Systems

A frequent problem I come across when discussing hard and soft systems views with engineers is that the terms ‘hard’ and ‘soft’ are rarely defined clearly. Based on conversations I’ve had over the years at the University of Bristol a common position can be characterised by the statement “all hard systems are embedded in soft systems.” I used this myself in a CSER conference paper in 2011 when talking about the EngD in Systems programme where I teach. However, since then I have arrived at the position that the epistemic shift that Peter Checkland and Susan Holwell describe is a more useful way of characterising hard and soft systems views [1]. Instead of the rather vague association of soft with the social world, people, and human intentionality, the soft systems view moves away from this ontological commitment and treats the definition as a question of epistemology, i.e. what can we know or find out about the world? The following quote from [1] spells out this epistemological position in a way that I find compelling. It is:
“phenomenologist, social constructivist, avoiding ontological commitment – sees the perceived (social) world as: culturally extremely complex; capable of being described in many different ways; and sees the “system” as one useful concept in ensuring good-quality debate about intentional action. The two observers both agree that the notion “system” can be useful, O seeing it simply as a name for (parts of) the real world, E seeing it as a useful intellectual device to help structure discussion, debate and argument about the real world.”
Where observer O corresponds to the ontological position and observer E to the epistemological. This is all usefully summarised in a table that I use with my students adapted from the original in [1]:
Hard and Soft Systems Viewpoints

Checkland and Holwell’s paper appears in a volume edited by Michael Pidd [3], which brings together the ideas developed in the Interdisciplinary Research Network on Complementarity in Systems Modelling (INCISM) Network that was funded by the Engineering and Physical Sciences Research Council (EPSRC).

John Morecroft was part of the network too and in his work on System Dynamics modelling [2] reflects on how it should be used in this soft systems sense. He paraphrases Checkland to state “… system dynamics modellers do not spy systems. Rather they spy dynamics in the real world and they organise modelling as a learning process, with the project team, to discover the feedback structure that lies behind the dynamics“.

Reflections on this hard/soft complementarity and the work of the INCISM network at the System Dynamics conference in 2004 are captured in the notes from the record of the plenary session Working Ideas, Insights for Systems Modelling: The Broader Community of Systems Thinkers.

All of this is neatly summarised by Peter Checkland himself in a colloquium delivered at Lancaster University in 2012. In this short video, Checkland outlines the development of Soft Systems Methodology emphasising its role as methodology, not method, and the origin of this particular definition soft systems as the systemic learning system designed to help us deal with the complexity of the world.

[1] Checkland, P., & Holwell, S. (2004). “Classic” OR and “soft” OR – an asymmetric complementarity. In M. Pidd (Ed.), Systems Modelling: Theory and Practice. Chichester: John Wiley & Sons, Ltd.
[2] Morecroft, J.D.W. (2007). Strategic modelling and business dynamics : a feedback systems approach. Chichester : John Wiley & Sons, Ltd.
[3] Pidd, M. (2004). Systems modelling : theory and practice. Chichester: John Wiley & Sons, Ltd.