Philippa Ruth Foot was an English philosopher and one of the founders of contemporary virtue ethics. Her work was inspired by Aristotelian ethics. Along with Judith Jarvis Thomson, she is credited with inventing the trolley problem. She was elected a member of the American Philosophical Society. She was a granddaughter of the U.S. President Grover Cleveland.

Judith Jarvis Thomson was an American philosopher who studied and worked on ethics and metaphysics. Her work ranges across a variety of fields, but she is most known for her work regarding the thought experiment titled the trolley problem and her writings on abortion. She is credited with naming, developing, and initiating the extensive literature on the trolley problem first posed by Philippa Foot which has found a wide range use since. Thomson also published a paper titled "A Defense of Abortion", which makes the argument that the procedure is morally permissible even if it is assumed that a fetus is a person with a right to life. She was elected a member of the American Philosophical Society in 2019.