The establishment of criteriological and manualized systems of diagnosis since the 1980ies has lead to a valuable increase in the precision and reliability of psychiatric diagnosis. On the other hand, the limits of this approach for clinicians and researchers are increasingly becoming apparent. In particular, the assessment of subjective experience is nearly excluded on the theoretical level and downplayed on the pragmatic level, with serious consequences for the validity of psychiatric diagnosis, for empirical research and, above all, for therapeutic purposes.

In my paper, I will argue that a thorough assessment and inclusion of subjective experience in our diagnostic systems will be indispensable for clinical, therapeutic as well as research purposes. To this purpose, I will distinguish three major approaches to the assessment of mental illness:

1. 1. The positivistic, objectifying or 3rd person approach as endorsed by DSM IV and ICD 10, focusing mainly on observable behavioural symptoms.

2. 2. The phenomenological, subject-oriented or 1st person approach, focusing on the patient's self-experience and exploring its basic, often implicit structures.

3. 3. The hermeneutic, intersubjective or 2nd person approach, mainly aiming at the co-construction of shared narratives or interpretations regarding the patient's self-concept, conflicts and relationships, as e.g. in psychodynamic approaches.

These three approaches will be compared regarding their respective values for psychopathological description, diagnosis, research and therapeutic purposes.