We will deal in this chapter some aspects of the work of Michel Foucault and some of the major figures of existentialism, a work that laid the sociological and philosophical foundations for the formation of the critical psychiatry and deinstitutionalisation movement. We will also explore the subject formation problematic, by looking into the contribution of phenomenological psychoanalysis and the connection between the phenomenological approach to philosophy and Franco Basaglia's thought, which constitutes the essential challenge to the psychiatric implementation of the biomedical model. In the same perspective, we will finally analyse some of the transformations that contemporary psychiatry underwent in the age of the ideological domination of neoliberalism in the domain of mental health as well.