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 . 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  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 :
Checkland and Holwell’s paper appears in a volume edited by Michael Pidd , which brings together the ideas developed in the Engineering and Physical Sciences Research Council (EPSRC) funded INCISM network – an abbreviation of Interdisciplinary Research Network on Complementarity in Systems Modelling.
John Morecroft was part of the network too and in his work on System Dynamics modelling  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“.
You can see me explaining this viewpoint at the systems thinking training session for the EU funded project STEEP (Systems Thinking for City Efficient Energy Planning) – see the section on Systemic Problem Structuring under Webinars and Videos.
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.
 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.
 Morecroft, J.D.W. (2007). Strategic modelling and business dynamics : a feedback systems approach. Chichester : John Wiley & Sons, Ltd.
 Pidd, M. (2004). Systems modelling : theory and practice. Chichester: John Wiley & Sons, Ltd.