The appropriation of complexity theory in health care.

The way in which complexity is usually interpreted in the health care literature misses the whole point of complexity theory, thanks to an influential but misleading series of articles in the BMJ. Complexity provides an explanation of patterns and structures in certain systems by modelling known outcomes at the global level in terms of stimulus-response rules governing the unilateral, non-intentional behaviour of individual units comprising the system. The BMJ articles overlook the explanatory function of complex systems, restore the link between order and design which complexity thinking disrupts, and interpret purely mathematical concepts in psychological terms. As a consequence, the health care literature typically regards complexity as a variation on democratic, collaborative, 'bottom-up' methods for the management of change in systems.