From Aristotle to contemporary biological classification: what kind of category is "Sex"?

This paper examines the nature of the categories of 'male' and 'female' as classificatory groupings, via an examination of this question in Aristotle's zoology and metaphysics. Tracing the use of Aristotle's logical categories of 'genus' and 'species' in his zoological works and contrasting this with the use of the terms in contemporary taxonomy, the paper shows that 'male' and 'female' are, in a significant sense, unclassifiable categories. Although Aristotle has no generic concept of 'sex' at his disposal, the paper shows how many English translations of his works introduce 'sex' as if in answer to the question of the nature of the categories of male and female. The paper then argues that the generic concept of sex covers over the problem of the classification of male and female in both Aristotle and contemporary biology (including botany, mycology and bacteriology), by introducing a classificatory genus ('sex') that does not in fact explain anything but rather (precisely in its trans-specific generality) needs explaining.