Understanding, testimony and interpretation in psychiatric diagnosis
Psychiatric diagnosis depends, centrally, on the transmission of patients’ knowledge of their experiences and symptoms to clinicians by testimony. In the case of non-native speakers, the need for linguistic interpretation raises significant practical problems. But determining the best practical approach depends on determining the best underlying model of both testimony and knowledge itself.
Internalist models of knowledge have been influential since Descartes. But they cannot account for testimony. Since knowledge by testimony is possible, and forms the basis of psychiatric diagnosis, it supports an externalist model of knowledge in general.
Internalist and externalist models of knowledge also suggest different ways of responding to the practical challenges of basing psychiatric diagnosis on testimony. Thus the argument in favour of externalism also supports a potentially empirically testable hypothesis about interpretion of non-native speakers for accurate psychiatric diagnosis: interpretation of non-English speakers should be as transparent and unhindered by specialised medical knowledge as possible.
Internalist accounts of knowledge are both intuitive and supported by Descartes’ seminal account of empirical inquiry. Internalists claim that the successful justification for knowledge claims must be wholly within the power of those who frame them. But however intuitive a claim about knowledge that is, it cannot account for a central aspect of psychiatric diagnosis: knowledge of patients’ experiences through testimony.
The very idea of transmission of knowledge by testimony suggests the need instead for an externalist model of knowledge. This also has practical significance in that it suggests that interpretation of non-English speakers should be as transparent and unhindered by specialised medical knowledge as possible.
In this paper we first sketch an internalist account of knowledge, but argue that it cannot account for the important role of testimony in psychiatric diagnosis. We then sketch McDowell’s contrasting externalist conception of testimony and, in that context, set out some practical problems for the testimonial transmission of knowledge in psychiatry. We then outline two opposing views of how best to cope with the practical problems in the light of competing internalist and externalist accounts of knowledge. According to the externalist approach to knowledge we favour, interpretation of non-English speakers should be as transparent and unhindered by specialised medical knowledge as possible. That is a hypothesis open to further empirical testing.
Internalist accounts of knowledge
In this section, we set out the distinction between internalist and externalist accounts of knowledge, starting with a traditional justified true belief analysis of it.
On the traditional analysis, arguably dating back to Plato, knowledge is identified with justified true belief. The analysis can be supported by the following informal considerations. One cannot know what one does not believe. (Thus on the traditional analysis, one does not know what one intends to buy simply by having, without memorising, a shopping list.) One cannot know falsely (though ‘know’ is sometimes used poetically to express deeply held but false beliefs). Finally, knowledge is not a matter of luck. If one has a belief that just happens to be true, for example, a belief one would also have had even had it been false, then that is not knowledge. Addressing this final point, the traditional model adds that true beliefs need also to be justified to be knowledge.
This traditional analysis of knowledge invites an ‘individualist’, or ‘internalism’ as it is more normally called, interpretation. If knowledge requires a justification, the justification should