Mat Walton BA (Hons), DPH, PhD
Technical Lead Social Systems
Institute of Environmental Science and Research Limited (ESR)
Kenepuru Science Centre: 34 Kenepuru Drive, Kenepuru, Porirua 5022

In this piece I introduce the concept of phase space (interchangeable with term ‘state space’).  Within a Complex Adaptive Systems (CAS) understanding of how systems change over time, I argue that phase space is important for designing interventions within a CAS.  Here I draw principally on the work of David Byrne and colleagues, located within dynamical systems and chaos (Capra & Luisi, 2014; Mitchell, 2009).

Complex Adaptive Systems are comprised of a set of interconnected elements.  Through the interaction of these elements phenomena ‘emerge’ as a feature of the system as a whole.  That is, we can’t look at individual elements within the system to understand the emergent phenomena (Byrne, 2013; Byrne & Callaghan, 2014).

A CAS often produces quite stable emergent phenomena over time.  When change does occur in emergent phenomena, it is due to a new configuration of the system – new elements, new connections or both.  Because emergent phenomena are the result of many interactions, there is large uncertainty in how a system will change (Eppel, Matheson, & Walton, 2011).  What is certain, is that the range of possible future system states is enabled and restricted by phase space.

Phase space can be thought of as the space within which a CAS can occupy.  While we can’t know precisely how a system might change, we do know that it will be within the phase space.  A change in emergent phenomena within a phase space may be incremental.  A radical change suggests a shift in phase space, a qualitative difference in the system (Byrne & Callaghan, 2014).

An example of a radical shift in emergent phenomena can be found in New Zealand’s government.  New Zealand is a parliamentary democracy.  In 1996, the system for electing parliament changed from First Past the Post to Mixed Member Proportional (MMP).  MMP is a system that is designed to produce coalition, multi-party governments.  That is, to have a majority of votes in parliament (required to become government), more than one party need to agree to work together.  Under First Past the Post, New Zealand had a history of mostly single party governments.  Since MMP, there has only been coalition governments.  While coalition governments were possible under First Past the Post, and single-party governments are possible under MMP rules, there is only a small set of conditions under which these outcomes are likely.

We could say that the phase space changed in 1996 from one where single party governments are usual, to one where coalition governments are usual.  In this case the rules around how members of parliament are elected changed the elements in the system (representation of political parties), and by implication the interaction between the elements (how political parties work together to achieve majority of parliamentary votes).

Phase space has implications for designing programmes and interventions.  Questions to consider include: is the intended outcome of my programme possible within current phase space?  Will the programme create a different phase space (that makes my programme outcomes more likely)?  How will I recognise if phase space has changed?

Byrne, D. (2013). Evaluating complex social interventions in a complex world. Evaluation, 19(3), 217-228. doi:10.1177/1356389013495617
Byrne, D., & Callaghan, G. (2014). Complexity Theory and the Social Sciences: The state of the art. Oxon: Routledge.
Capra, F., & Luisi, P. L. (2014). The Systems View of Life. Cambridge: Cambridge University Press.
Eppel, E., Matheson, A., & Walton, M. (2011). Applying complexity theory to New Zealand public policy: Principles for practice. Policy Quarterly, 7(1), 48-55. Retrieved from
Mitchell, M. (2009). Complexity: A guided tour. Oxford: Oxford University Press.

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