How are we to understand the notion of concept, the very concept of concept itself? One natural way, it seems to me, is to take Fregean sense as a model, and imposing similar constraints on a theory of concepts. This approach has the advantage, among others, of allowing for a distinction to be made between publicly shared, objective concepts, on the one hand, and private, subjective mental representations on the other - a distinction which, I believe, is desirable for various (...) reasons. One problem with Frege. (shrink)