In disputes about conceptual analysis, each side typically appeals to pre-theoretical 'intuitions' about particular cases. Recently, many naturalistically oriented philosophers have suggested that these appeals should be understood as empirical hypotheses about what people would say when presented with descriptions of situations, and have consequently conducted surveys on non-specialists. I argue that this philosophical research programme, a key branch of what is known as 'experimental philosophy', rests on mistaken assumptions about the relation between people's concepts and their linguistic behaviour. The (...) conceptual claims that philosophers make imply predictions about the folk's responses only under certain demanding, counterfactual conditions. Because of the nature of these conditions, the claims cannot be tested with methods of positivist social science. We are, however, entitled to appeal to intuitions about folk concepts in virtue of possessing implicit normative knowledge acquired through reflective participation in everyday linguistic practices. (shrink)