Critical Mass and Metaphor Models

Bruce Edmonds has reviewed Phillip Ball’s 2005 book Critical Mass: How One Thing Leads to Another for the Journal of Artificial Societies and Social Simulation (JASSS). Providing a popular science account of the history the development of sociophysics and abstract social simulation the book (apparently – I haven’t read it) makes the common mistake of conflating models and their results for the systems they have been built to represent. In Edmonds’ words:

In all of this the book is quite careful as to matters of fact – in detail all its statements are cautiously worded and filled with subtle caveats. However its broad message is very different, implying that abstract physics-style models have been successful at identifying some general laws and tendencies in social phenomena. It does this in two ways: firstly, by slipping between statements about the behaviour of the models and statements about the target social phenomena, so that it is able to make definite pronouncements and establish the success and relevance of its approach; and secondly, by implying that it is as well-validated as any established physics model but, in fact, only establishing that the models can be used as sophisticated analogies – ways of thinking about social phenomena. The book particularly makes play of analogies with the phase transitions observed in fluids since this was the author’s area of expertise.

This book is by no means unique in making these kinds of conflation – they are rife within the world of social simulation.

(from Edmonds 2006, JASSS)

And not only within social simulation. In a previous paper, I highlighted with some colleagues that the name given to the ‘Forest Fire Cellular Automata’ made famous by Per Bak and colleagues, is better treated as a metaphor than an accurate representation of the dynamics of a real world forest fire (Millington et al 2006). This may be a seemingly an obvious point to make, but simulation models can provide an unjustified sense of verisimilitude and the appearance of the reproduction of complex empirical systems’ behaviour by simple models can lead to the false conclusion that those simple mechanisms are the cause of the observed complexity.

In a forthcoming paper with Dr. George Perry in a special issue of Perspectives in Plant Ecology, Evolution and Systematics, we discuss the lure of these ‘metaphor models’ and other issues regarding the approaches to spatial modelling of succession-disturbance dynamics in terrestrial ecological systems. I’ll keep you posted on the paper’s progress…

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