it is a mistake to believe that the existence of “hard cases” that do not fall into a clear category means that the underlying dichotomy is incoherent. It would be wrong to say that the existence of people who have some hair means that there is no such thing as people who either are bald or have a full head of hair; similarly, it is wrong to say that the existence of people who are intersex means that there is no such thing as people who are biologically male or biologically female.
