Psychiatric classification, vagueness and tacit knowledge
DSM III aimed to improve the reliability of psychiatric diagnosis via an operationalist emphasis on ‘observable’ signs and symptoms and the initial downplaying of aetiological theory. Signs and symptoms are first elicited and then syndromes derived through diagnostic algorithms. Whilst this has prompted the charge that reliability has improved only at the cost of validity, there has also been a criticism, from European psychiatrists, that the signs and symptoms articulated within DSM III and IV are vague by contrast with the specification provided by explicitly phenomenological psychiatry. Rather than providing a reliable foundation, the connection between individual symptoms and conditions in the DSM lacks specificity. By contrast, phenomenological psychiatry can chart a correlation between schizophrenia, for example, and particular kinds of catatonia or delusional structure. Correlations are not between schizophrenia and delusions in general but delusions with a specific schizophrenic colouring.
In this chapter, I attempt to shed light on these claims without presupposing the phenomenological tradition but instead by forging a connection between diagnosis and one construal of tacit knowledge. Taking the latter to be a context-dependent, but conceptually structured practical skill, I suggest that the top-down approach to psychiatric symptoms contains the vagueness of DSM descriptions of symptoms through context-dependent recognitional skills. But this is merely a more than usually pronounced instance of the link between tacit knowledge and what Polanyi’ calls the ‘art of denotation’.