Carlos Castilla del Pino (1922-2009) was a Spanish psychiatrist and essayist with a wide work ranging from neuropsychiatry to social psychiatry. His essays include interesting psychopathological, anthropological and semiotic ideas.

The “axiom of behavioural significance” proposes that human behaviour is not an objective event but a meaningful act. As the objective of human behaviour is relation between human beings, it must be studied only under this communicative perspective.

Based in this axiomatic approach of Castilla del Pino, some arguments of interest to philosophy of psychiatry will be exposed:

– Mind is based in language and language is a communicative acts system in need of a dialogic community, namely, in need of a group of interacting brains. So, referring to the “brains-mind problem” is proposed to be preferred instead of referring to the “brain-mind problem”. Mind is a language-based emergent property of the social group, not a property of a single brain.

– The intention of human behaviour and the content of mental subjective phenomena should not be taken as a sign of any brain disease. Human behavior and mental representations always refers to a social group and a social context, not to a single brain. The only disease indicators we can take as disease signs are the formal aspects of behaviour and mind contents, as disexecutive syndrome or mental automatism are.

– As a corollary, it is proposed that neurology and psychiatry do not have any epistemic difference, leading to defence the unification of clinical neuroscience.