Abstract

This chapter contrasts the recent emphasis on operationalism as the route to reliability in psychiatry with arguments for an ineliminable role for tacit knowledge. Although Michael Polanyi popularized the idea of tacit dimension, the chapter argues that two clues he offers as to its nature-that we know more than we can tell and that knowledge is an active comprehension of things known-are better interpreted through regress arguments set out by Ryle and Wittgenstein. Those arguments, however, suggest that tacit knowledge is not inexpressible but merely inexpressible in context-free terms. The chapter suggests instead that tacit knowledge is best understood to be context-dependent practical knowledge. So understood, the regress arguments suggest that the operational approach to psychiatric diagnosis can never free itself from a tacit dimension. Given that claim, then Parnas' opposing view of diagnosis can be seen as a way to embrace, rather than deny, the importance of tacit knowledge and skilled clinical judgment for psychiatry.