This essay defines the ontology of mental illness or mental disorder in non-biomedical terms, as consisting of problematic propositional mental content rather than organic brain malfunction. This allows for a causal theory of mental disorder to be located within the parameters of existential difficulties rather than biological pathology, and contradicts the arguments made in defense of the necessity of psychotropic medications for the alleviation of mental distress. This in turn supports the argument that mental disorders can be treated, if not cured, by means of philosophy.