When a baby is born whose reproductive organs do not fit neatly into a binary idea of biological sex, they are deemed intersex. Often, doctors and parents decide to do surgery soon after birth, and in many cases administer hormones, to make intersex children fit into male/female categories. Intersex is treated as a medical problem: their physiologies are quickly dismissed as impossible, freakish, or even monstrous. Hermaphrodite Logic is a history of intersex liberation, exploring both the campaigns and the thinking that began to challenge clinical approaches to sex from the 1990s. Existing between the tidiest attempts to categorise sex, intersex people are typically 'known over', and can be badly mistreated by those trying to make them 'fit' more limited views of sex. Their movement has had to challenge those that once spoke over them, and to make sense of their lives using their own terms, and communities. Hermaphrodite Logic foregrounds the lives and political struggle of intersex people who founded a political movement to end the worst mistreatment.