Alex Byrne’s article, “Are Women Adult Human Females?”, asks a question that Byrne treats as nearly rhetorical. Byrne’s answer is, ‘clearly, yes’. Moreover, Byrne claims, woman is a biological category that does not admit of any interpretation as (also) a social category. It is important to respond to Byrne’s argument, but mostly because Byrne’s argument is a paradigmatic instance of a wider phenomenon. The slogan “women are adult human females” is a political slogan championed by anti-trans activists, appearing on billboards, pamphlets, and anti-trans online forums. In this paper, I respond to Byrne’s argument, revealing significant problems with its background assumptions, content, and methodology.