The importance of psychopathology for psychiatry is threefold: it is the common language that allows psychiatrists to understand each other while talking about patients; it is the ground for classification and diagnosis; it makes an indispensable contribution to understanding patients’ personal experiences and their life-worlds. The latter is the task of phenomenological psychopathology which goes beyond the description of isolated symptoms and the use of some of those symptoms to establish a diagnosis. It aims to understand the meaning of a given world of experiences, grasping the underlying characteristic modification that keeps the symptoms meaningfully interconnected.

This kind of practice connecting a given experience with its transcendental condition of possibility may also have etiopathogenetical implications, thus linking the research on meanings to that on causes of mental symptoms. This path to causal or genetic understanding in psychopathology was opened by Jaspers, who described it as a kind of knowledge that establishes meaningful connections between psychic phenomena: psychic events emerge out of each other in a way which we can immediately understand. Husserl also developed, beyond static phenomenology, a kind of phenomenology called explanatory based on the concept of motivational causality. This is a kind of diachronic understanding studying the way complex modes of lived experience are constituted via the synthesis of more basic modes of experience. Analyzing the implicit dimension of experience, phenomenological psychopathology allows for a comprehension of the pre-reflective structures of subjectivity from which manifest symptoms arise and moves beyond pure description toward an understanding that embraces both the overall unity of a person's subjectivity and its development over time. This kind of understanding, based on the unfolding of the basic architecture of the life-world, and on the structures of subjectivity which allegedly generate them, allows to both rescue the personal meaning and the personal motivation of a given symptom.

An example of genetic phenomenology is the study of symptom progression in schizophrenia: patients experiencing abnormal bodily sensations may develop a delusion of alien control over their own body. Feelings of extraneousness of parts of one's body, of heaviness, lightness, shrinking, enlargement, traction, etc. - occurring abruptly and often migrating from one bodily zone to another - may lead to typically schizophrenic symptoms. Delusions of being controlled, the most “bizarre” symptom of schizophrenia, become understandable as motivated by the patients’ need to give an explanation for their disturbing changes in bodily experiences. These abnormal bodily sensations can be related to a deep and characteristic change in the basic structures of subjectivity: persons with schizophrenia feel like “deanimated bodies”—the living body becomes a functioning body, a thing-like mechanism in which feelings, perceptions and actions take place as if they happened in an outer space - and “disembodied spirits”— they are affected by the sharp awareness of observing that appears separated from the experience of existing. This basic disturbance is typical and contributes to a clear-cut differentiation—better than surface signs and symptoms—between schizophrenia and other forms of psychotic existence.