Friendly amendment: a commentary on Doyle and Ford's proposed re-definition of ‘mental model’

Some amendments are proposed to a recent redefinition of the ‘mental model’ concept in system dynamics. First, externalised, or articulated mental models should not be called ‘cognitive maps’; this term has a well established, alternative meaning. Second, there can be mental models of entities not yet existing beyond an individual's mind; the modelling of planned or desired systems is possible and recommended. Third, saying that mental models ‘maintain’ social systems connects with some exciting research opportunities for system dynamics; however, it is probably an accidental distraction from the intended meaning of the redefinition. These minor criticisms apart, the new definition of ‘mental model of a dynamic system’ is welcomed as a useful contribution to both research and practice.