Peter Albert David Singer, the Ira W. DeCamp Professor of Bioethics in the University Center for Human Values (UCHV), transferred to emeritus status on July 1, 2024, after twenty-five years on Princeton University’s faculty. Described by many colleagues, and ranked on various surveys, as among the most famous and influential living philosophers, Peter is best known for his work in applied ethics, or how ethics should influence the decisions we make every day. At the core of many of his publications is the utilitarian principle that “the greatest good of the greatest number is the only measure of good or ethical behavior”—albeit that during his years at Princeton, Peter fundamentally changed his view on the best interpretation of utilitarianism. He gave up the anti-realism and preference utilitarianism that he had initially adopted as a student of Oxford philosopher R. M. Hare in favor of moral realism and hedonistic utilitarianism. The practical implications of his utilitarian commitments developed in a more continuous way, embodied in his decision, when awarded the 2021 Berggruen Prize for Philosophy and Culture, to give away the entire $1 million prize. 

Peter was born on July 6, 1946, in Melbourne, Australia, to Austrian Jewish parents who had emigrated to Australia in 1938 after Austria was annexed by Nazi Germany. After attending the Preshil School and Scotch College, Peter studied at the University of Melbourne, earning a bachelor’s degree in 1967 and a master’s degree in 1969. In 1971, he received a B.Phil. from the University of Oxford, where he served as a Radcliffe Lecturer for several years afterward. After teaching briefly at New York University and La Trobe University, Peter joined Monash University’s Department of Philosophy as a professor in 1977. There he served as chair of the department, associate dean of the faculty of arts, director of the Centre for Human Bioethics, and codirector of the Institute for Ethics and Public Policy, before joining Princeton’s faculty in 1999. In 2005, Peter took up a partial duty-time arrangement at Princeton, so that he could spend each spring semester in Australia, where he served as Laureate Professor at the University of Melbourne’s Centre for Applied Philosophy and Public Ethics from 2005 to 2012 and its School of Historical and Philosophical Studies from 2013 to 2019. 

In Animal Liberation: A New Ethics for Our Treatment of Animals (HarperCollins, 1975), Peter extended the utilitarian principle to include animals, which are capable of feeling pain. Because of animals’ capacity for suffering, he argued that vegetarianism or veganism should be adopted by humans, and that experimentation on animals is largely unethical. The book features on TIME magazine’s list of 100 Best Nonfiction Books published in the last century.  

Equally influential has been Peter’s 1972 essay, “Famine, Affluence, and Morality”—republished in book form (Oxford, 2015) with a foreword by Bill and Melinda Gates—which argued that the affluent are morally obligated to donate a significant proportion of their income to help alleviate global poverty, and that these obligations are not lessened by distance or national boundaries. To explain why, Peter developed a claim that has become famous as a keystone of a certain line of ethical reasoning: that it would be immoral for someone to pass a child drowning in a shallow pond and not stop to save them due to the costs that they would incur by doing so, so long as those costs are less severe than the harm that they could prevent (for example, a potential rescuer is not excused from helping just because they are wearing nice clothes and wish to avoid a dry cleaning bill). 

If bad things—such as famine or homelessness—can be prevented without “sacrificing anything of comparable moral importance,” the moral thing to do is to act. Singer’s public as well as academic championing of this principle of practical ethics contributed to the rise of effective altruism, a social and philosophical movement that maintains that we should try not only to reduce suffering but to do so in the most effective manner possible, based on reasoning, evidence, and research. While this movement has been developed by many philosophers and laypeople in many different directions, and has also been subject to various lines of criticism, Peter’s own focus in The Life You Can Save: Acting Now to End World Poverty (Random House, 2009) and The Most Good You Can Do: How Effective Altruism Is Changing Ideas About Living Ethically (Yale University Press, 2015)—and also in cofounding the nonprofit The Life You Can Save—has been to identify actionable ways in which people can make the most impact in helping to reduce global poverty and other forms of preventable suffering. As Princeton colleague Angus Deaton has observed: “It is hard to think of any scholar whose work has been as practically influential as has Peter’s. Among philosophers, we would have to go back a very long way, perhaps as far as Bentham and Mill. His writings on practical ethics really did change the world.”

Peter has also made significant contributions to many other areas of philosophy, including studies of the ideas of Henry Sidgwick and Karl Marx, as well as being one of the key contributors to the formation of the field of bioethics. The breadth of his contributions is indicated by the topics of the farewell conference UCHV is convening in his honor, including panels on utilitarianism, freedom of expression, extreme poverty, bioethics, animals, and the significance of ethics. He has also demonstrated his commitment to free speech in other ways, including as cofounder of the Journal of Controversial Ideas.

Many of his books have been translated into multiple languages and appeared in multiple editions, and he has given dozens of named lectures and received many awards and honors, including appointment as a Companion of the Order of Australia in 2012. This May, Peter was honored with the University’s prestigious Howard T. Behrman Award for Distinguished Achievement in the Humanities. 

President Emeritus Harold T. Shapiro has reflected on Singer’s impact on Princeton thus: “We have many distinguished scholars at Princeton who have made important contributions to the world of scholarship in the humanities, but few have captured our students’ intellectual imagination in quite the same way.” Peter has served as director of the Ira W. DeCamp Bioethics Seminars, convening discussions at the intersections of philosophy, biology, medicine, ecology, and public policy. As a teacher, he created the course Practical Ethics, which has reached thousands of undergraduates (enrolling hundreds each time it has been offered on a biannual basis), drawing them into a community of ethical concern while demonstrating a deep commitment to freedom of speech and freedom of thought.  

Peter also served as indefatigable mentor and faculty adviser to the student leadership of the Human Values Forum, where undergraduate students and faculty members have met weekly for two decades in an informal setting over dinner to discuss current and enduring questions concerning ethics and human values. His regular commitment, week in and week out, to participate in a student-led activity helps sustain free inquiry and discourse about ethical questions on campus in a remarkable way.

As preparations were underway for a UCHV conference on Peter’s work this May (at which all catering will be vegan), Peter requested that we avoid using the word “retirement” in describing the event. Even as he says farewell to his active role at Princeton, we can expect that his championing of the humanitarian causes, so powerfully underpinned by his moral clarity and philosophical consistency, will be a continuing vocation.

Written by members of the University Center for Human Values faculty.