The need for a more and more comprehensive classification system of mental disorders that responds to the difficulties of the subject is more imperative than ever. The purpose of this study through a critical look is to highlight the way a diagnostic system "thinks" about the symptoms of each subject. Methodologically, in the context of the modern international literature, an attempt is made to capture perceptions from the field of scientific knowledge regarding psychodiagnostic systems that dominate the mental health field. More specifically, it reflects the way in which each psychodiagnostic system classifies symptoms in the context of a phenomenology of things, leaving aside the personal pain and the uniqueness of each subject. In conclusion, it seems that psychodiagnostic systems talk about symptoms that are divided into clusters and each of them gets a name. They don’t talk about causes, they don’t take into account the difference, nor the environment and the temperament of each person, as a result of which difficulties are created because they do not aim therapeutically at what gives birth to the symptom, but at what each symptom shows.