Peter Singer is an Australian philosopher widely regarded as one of the most influential living philosophers, particularly for his contributions to the animal liberation movement. Born in Melbourne to parents who fled the German annexation of Austria, Singer was educated at Preshil and Scotch College. He studied law, history, and philosophy at the University of Melbourne, and earned his B.Phil. from Oxford in 1971. Singer's master's thesis was entitled, "Why Should I Be Good?" In his touchstone work, *Animal Liberation*, Singer expanded on the question, arguing that the only measure of morality is the greatest good for the greatest number, popularizing the term "speciesism" as the practice of preferring humans over other animals. Other works, such as *Practice Ethics*, develop his ethical standpoint, the preference utilitarian perspective.

John Hare is the Noah Porter Professor of Philosophical Theology at Yale Divinity School. He is most widely known for his 1996 book *The Moral Gap*, in which he analyzes a gap between ethical duty and ability noted in Kant's philosophical writings. Hare argues that this moral gap cannot be bridged apart from religion. The son of influential British utilitarian philosopher R. M. Hare, John Hare received his B.A. from Balliol College, Oxford, and his Ph.D. from Princeton University in 1975. After teaching at Lehigh University and Calvin College, he moved to Yale, where he has been a professor of theology since 2003.