Peter Albert David Singer (born 6 July 1946) is an Australian moral philosopher who is Emeritus Ira W. DeCamp Professor of Bioethics at Princeton University. Singer's work specialises in applied ethics, approaching the subject from a secular, utilitarian perspective. He wrote the book Animal Liberation (1975), in which he argues for vegetarianism, and the essay "Famine, Affluence, and Morality", which argues the moral imperative of donating to help the poor around the world. For most of his career, he was a preference utilitarian.
https://en.wikipedia.org/wiki/Peter_Singer