Judith Butler (born February 24, 1956) is an American philosopher. She was born in Ohio. She got her Ph.D. in philosophy from Yale University in 1984. She lives in Berkeley, California, with her partner Wendy Brown. In 1990 Gender Trouble was published by Routledge. It is considered one of the key works of contemporary feminism. In the book Butler talks about her theory of gender performativity, which is that gender, along with sex and sexuality, is something you "perform" rather than an expression of human biology.