Carving Mental Disorder at the Joints. An Essay in the Philosophy of Psychopathology

A traditional assumption in medicine has been that diseases are natural phenomena which may be discovered and investigated by empirical science. Nosology - the classification of diseases - is thus also a matter of empirical science, just like systematics in biology. The dissertation argues that this traditional assumption is defensible in principle, and that psychopathological kinds can be natural kinds. For one thing, it says that the sine qua non of pathological conditions – the thing that makes them pathological – is some kind of natural property. A natural property in this context means empirical-biological, as opposed to a normative-ethical one. The dissertation argues that pathological status is a matter of causing or involving evolutionary dysfunctions, that is failures to execute naturally selected functions. Such a concept of pathology is able to explain why every species on earth can be sick. Furthermore, it can explain why the human mind can become disordered to the extent it has evolved biological dysfunctions. Finally, a strict naturalistic concept of pathology means that not all pathological conditions ought to be treated. In spite of this, the dissertation argues that clinical medicine has no need for a different or another concept of disease. Using the example of ADHD, a common child and adolescent psychiatric disorder, the dissertation argues that the official psychiatric categories defined in DSM-IV and ICD-10 cannot be real patterns in nature, and thus ought to be discarded. However, a flawed diagnostic philosophy should not be taken to mean that psychopathological kinds cannot be natural kinds. Although mental disorders are not microstructural essences like the basic elements, the last part of the dissertation argues that they still can be natural kinds in the sense of “homeostatic property clusters” à la Richard Boyd and Paul Griffiths.