Multiple Pathways
One vexing problem highlighted by research in developmental psychology is that some disorders involve multiple etiologic pathways. The principles of equifinality and multifinality, derived from general systems theory, hold for many disorders. Equifinality is the concept that the same phenomenon may result from several different pathogens. For example, infantile autism results from congenital rubella, inherited metabolic disorder, or other factors. Multifinality is the concept that one etiologic factor can lead to any of several psychopathologic outcomes, depending on the person and context. Early physical abuse might lead to conduct disorder or to dysthymic disorder, depending on the person’s predilections and the environmental supports for various symptoms; poverty predisposes one toward conduct disorder but also substance abuse disorder.
The diversity in processes and outcomes for disorders makes the systematic study of a single disorder difficult. Unless scholars consider multiple disorders and multiple factors simultaneously, they cannot be sure whether an apparent etiologic factor is specific to that disorder. Inquiry into one disorder benefits from a conceptualization within a larger body of development of normal adjustment versus problem outcomes. The broad coverage of developmental psychology provides the grounding for inquiry into various disorders.
