Abstract
I use Ian Hacking 's views to explore ways of classifying people, exploiting his distinction between indifferent kinds and interactive kinds, and his accounts of how we 'make up' people. The natural kind/essentialist approach to indifferent kinds is explored in some depth. I relate this to debates in psychiatry about the existence of mental illness, and to educational controversies about the credentials of learner classifications such as 'dyslexic'. Claims about the 'existence' of learning disabilities cannot be given a clear, simple and unambiguous interpretation. In particular I show that science cannot deliver a definitive taxonomy of learner categories, and that this has important implications for teachers and policy makers