The development of a psychotherapist’s diagnostic skills can retrace the history of the development of diagnosis in psychotherapy just like ontogenesis retraces phylogenesis. Historically we witnessed the passage from anti-diagnostic positions to constructive critical positions. It has been suggested that since diagnosis is an unavoidable component of clinical reasoning, anti-diagnostic positions reflect confusion between different levels of clinical reasoning (informal, formal and institutional) and different levels of diagnostic systems (school-specific, psychodynamic, health system). The Authors stress the importance of di-agnosis in the development of psychotherapy, its recognition in health systems both for the identification of the population it is addressed to and the recognition of psychotherapy as an evidence-based treatment. The Authors enumerate the risks of marginalization run by non-evidence-based psychotherapeutic models given the indications of the European Union which invite Member Countries to include the treatment of common mental health disorders in primary care. In closing they present a process in four steps for favoring the development of research in the models at risk of marginalization through the meta-analysis of single cases and benchmarking.
Keywords: Diagnosis, marginalized and emerging models of psycho-therapy, research of single case, benchmarking].