Objective: The assumptions and goals underlying current systems of classification are critically examined.
Method: Current systems of classification are based on assumptions that health can be adequately defined as the absence of disorders and that psychiatric disorders are discrete disease entities that can be categorically defined. These assumptions appear to be inconsistent with available knowledge of the psychobiology, genetics, development and evolution of thoughts, emotions, and behaviour.
Results: An alternative psychobiologically based paradigm is described based on the model that mental health and its disorders are emergent properties of complex interactions among multidimensional neuroadaptive systems.
Conclusions: This permits an explicit definition of optimum mental health and a descriptive system that is more effective for professionals, individuals, and society in understanding and achieving increased adaptive fitness.