Classification of psychopathology and unifying theory: The ingredients of a Darwinian paradigm shift in research methodology

The field of psychopathology needs a paradigm shift to revitalise its research methodology and translational practice. We describe Darwin’s transformation of biology and its implications for science and culture, and we infer the implications of an analogous approach to psychopathology. Darwin challenged the assumptions of the biological classification system with compelling evidence to support a quantifiable, mechanistic theory of change across all life. Specifically, he showed that species were changeable, that individuals showed substantial variation in their features, and that these features were functional adaptations to the environment. Similarly, there is substantial evidence of continuous change, shared symptoms and functionality across the categories of psychiatric classification. Our novel research methodology, inspired by perceptual control theory, include both qualitative and quantitative methods, and entail the study of universal processes within heterogeneous samples and studying dynamic processes prospectively within individual cases, drawing direct analogies with evolutionary dynamic systems (e.g. trade-offs, speciation).