B a c k g r o u n d . The article demonstrates the development and influence of the main diagnostic systems in psychiatry, such as the DSM and the ICD, on the concept of psychiatric diseases. The problem of classification of psychiatric disorders is one of the main topics that is the field of study of the philosophy of psychiatry. The correct diagnosis within a particular diagnostic system directly affects the choice of appropriate drug treatment, psychotherapy and social support for people suffering from mental disorders. Misdiagnosis has not only negative medical but also social consequences, leading to stigmatization and avoidance of people suffering from mental disorders. M e t h o d s . The research uses an integrated approach to the analysis of psychiatric diagnostic systems, including historical, comparative and interdisciplinary methods. The application of the historical method contributed to a detailed study of the evolution of psychiatric diagnostic systems and changes in approaches to the classification of mental disorders. A comparative analysis of the main diagnostic systems was carried out, considering their structure, diagnostic criteria and interaction. The interdisciplinary method involves the integration of knowledge from psychiatry, philosophy, medical history, cultural studies, and psychology, providing a deep understanding of the medical, philosophical, social, and cultural aspects of mental disorders. R e s u l t s . The article analyzes the historical development of ideas and methodology for the classification of mental disorders from ancient Greece to the present. From Hippocrates and Plato to Sydenham, Kabanis, Pinel, and Eskierol, the authors trace the evolution of understanding of mental disorders, emphasizing the shift in emphasis from etiological theories to more descriptive and categorical models. The authors describe the current state of the DSM and ICD classification systems, which play a dominant role in psychiatric science and subsequent social support and welfare for people suffering from mental disorders. Changes that have occurred in these systems and their impact on psychiatric practice and research are discussed. Considerable emphasis is placed on the history of the diagnosis of post-traumatic stress disorder (PTSD), which becomes a symbolic indicator of the complexities and challenges associated with the modern classification of mental illness. The authors consider the phenomenological method as a tool for a deeper understanding of PTSD, especially in the context of the constant psychotraumatic factors of war, the consequences of which generate new challenges for Ukrainian psychiatric practice. The authors present a case study using the phenomenological approach to diagnose PTSD, which demonstrates the need for a detailed analysis of patients' internal experience for accurate diagnosis and effective treatment. C o n c l u s i o n s . The conclusions emphasize the importance of integrating philosophical methods into the diagnosis and analysis of mental illness in clinical practice. The authors call for the development of interdisciplinary research involving both philosophers and mental health professionals to develop more detailed and person-centered approaches to the diagnosis and treatment of mental disorders.
