On unjustified ethical conclusions of evolutionary psychiatry
Marcin Piotr Nowak

Evolutionary psychiatry is a field of psychiatry that uses laws and concepts discovered by evolutionary biology for describing psychiatric disorders. Being partially associated with genetic factors, some common psychiatric disorders (psychotic, mood and anxiety disorders) should be subject to natural selection, whereby traits diminishing fitness would be deleted from the population. Yet, this is not the case, so it is possible that they play some positive role. This function may be disturbed by therapy, hence the question about the ethical aspects of treatment – if it is, in fact, harmful. Argumentation proving the deleterious effect of psychiatric treatment is, however, incorrect, because:
- It contains unjustified move from facts to moral statements, first described by the philosopher David Hume (known as Hume’s guillotine or the “is–ought” gap). Modern day philosophy presents variable views on this inference, but usually it is treated as invalid.
- Evolutionary biology is not concerned with the patient’s interest, since natural selection is associated with fitness – not necessarily the fitness of a given patient, but frequently the fitness of selfish genes or inclusive fitness of an entire group of individuals. What is more, even the fitness of a patient does not have to correspond with their wellness.
In conclusion, neither evolutionary biology nor evolutionary psychiatry can be a source of moral statements. Its role consists in providing knowledge about the aetiology of psychiatric disorders, which can contribute to the improvement of therapy.