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 is known for writing books that are hard to understand. She lives in Berkeley, California, with her partner Wendy Brown. In 1990 Gender Trouble was published by Routledge. In the book Butler says that sex is gender. She talks about her theory of gender performativity.