Leon Richard Kass (1939- )

By: Samuel Philbrick

Leon Richard Kass

A PhD and medical doctor turned ethicist, Leon Kass calls himself an unlicensed humanist. Throughout his unique career he has sought to impact others and engage important cultural issues. This he has accomplished over the course of many years by studying biochemistry, teaching humanities, writing articles and books on ethics, and serving as chair of the President’s Council on Bioethics. Kass has become a controversial figure in the field of embryology, having written numerous articles and overseen the publication of several reports on a range of topics including the ethics of cloning, assisted reproduction technology, and human stem cell research.

A man whose publications are marked by alignment with generally traditional Judeo-Christian values, Kass was born into a progressive, Yiddish-speaking, socialist home in Chicago on 12 February 1939. A self-described child of the enlightenment, despite his Jewish heritage Kass never had a bar mitzvah and did not go to a synagogue as a young man. He remembers thinking that religion was an outdated matter of superstition, but nevertheless describes his parents as patriotic and highly moral.

Beginning his career at fifteen when he entered the University of Chicago in 1954, Kass followed the recommendation of a pre-medical advisor, and took courses in biology and calculus. He graduated in four years with a BS in biology and honors, and was subsequently accepted into the University’s Medical College. In medical school he married his fiancé, now Amy Kass, in 1961. After graduating with honors in 1962, Kass began another round of postgraduate education at Harvard University, entering its biochemistry PhD program in 1963 to pursue research and to avoid the Vietnam War draft. He avoided the war not because, as he said, of opposition to the war itself but rather a dislike of wasting time and having to take orders. Kass would receive his PhD in 1967, but more transforming than exploration of biochemical research was a trip he took with his wife in the mid-1960s.

In 1965, as a member of the Medical Committee for Human Rights, he and Amy traveled to rural Mississippi to do civil rights work with African-American farmers. Kass began to think about the differences he saw between his colleagues at Harvard and the farmers. Though they had none of his Cambridge peers’ education in the arts and sciences he felt the farmers had the greater share of honesty and good character. Reflection on this led to a paradigm shift in his philosophy as he began to think about the idea that it was not only injustice and strife that threatened culture. He began to wonder about whether advancing scientific research could dismantle what he termed the concept of humanity.

From the beginning of his writing exploring humanness, Kass approached issues key to embryology. In 1971 he published “Babies by Means of in vitro Fertilization: Unethical Experiments on the Unborn?” in Science. He published other articles during the decade opposing experimentation on embryos created with in vitro fertilization (IVF) and attempts to create children with the technique. Later, Kass would recant his assertion that using IVF within marriage to procreate was unwise; however, he maintained his opposition to scientific experimentation on embryos created with IVF.

Throughout the 1970’s Kass moved between teaching positions and conducting research. He tutored at St. John’s College from 1972 to 1976, and did research sponsored by a grant from the National Endowment for Humanities from 1973 to 1974. In 1974 he also took a position as the Joseph P. Kennedy, Sr., Research Professor in Bioethics at Georgetown University, which he would hold for two years. In 1976 he left his positions at St. John’s and Georgetown to become the Henry R. Luce Professor of the Liberal Arts and of Human Biology at the University of Chicago. He stayed in this department until 1984 when he became a professor in The College and Committee on Social Thought. In his years as a professor at the University of Chicago he has taught numerous graduate and undergraduate courses including several on Greek philosophy, the philosophy and ethics of science, and a year-long freshman seminar called “Human Being and Citizen.”

In 1985 Kass penned his first book, Toward a More Natural Science, Biology and Human Affairs, in which he expresses concerns about unlimited biological research and argues for a science that helps people encounter–as he dubs it–the mysterious. His next book, The Hungry Soul: Eating and the Perfecting of Our Nature, was published in 1994, with a second edition released in 1999, and looked at the morality and culture surrounding the act of eating. In 1998 he wrote The Ethics of Human Cloning with co-author James Q. Wilson. In the year 2000 he and his wife Amy Kass compiled Wing to Wing, Oar to Oar: Readings on Courtship and Marrying. In 2002 he released Life, Liberty, and the Defense of Dignity: An Ethical Inquiry and in 2003 he authored The Beginning of Wisdom: Reading Genesis.

Before publishing The Beginning of Wisdom, Kass found himself in the national spotlight when he was appointed Chairman of the President’s Council on Bioethics in August 2001. It was left to Kass to nominate many of the eighteen members of the council (all of whom had to be approved by President George W. Bush). Kass faced accusations that he recruited only council members who shared his conservative ideals. However, he consistently defended the diversity of the council, and, as Peter Berkowitz points out in “The Pathos of the Kass Report,” as many as eight of the eighteen council members voted for Al Gore in the 2000 presidential election. The President’s Council on Bioethics produced seven reports under Kass’ chairmanship on topics ranging from humanity and the pursuit of happiness, to ethical treatment of the elderly, to human cloning and stem cell research. Especially relevant to the field of developmental biology were “ Human Cloning and Human Dignity: An Ethical Inquiry,” published in July 2002, “ Monitoring Stem Cell Research,” published in January 2004, “Reproduction and Responsibility: The Regulation of New Biotechnologies,” published in March 2004, and the “ White Paper: Alternative Sources of Human Pluripotent Stem Cells,” published in May 2005.

Kass left his position as chairman in 2005, and has since maintained his position at the University of Chicago as the Addie Clark Harding Professor in the Committee on Social Thought and the College, and as the Hertog Fellow in Social Thought at the American Enterprise Institute. He has received numerous awards for excellence in teaching, and in 2009 he was invited to give the Jefferson Lecture in the Humanities, which is described by the National Endowment for the Humanities as the highest honor given by the government for distinguished intellectual achievement in the humanities.

In his lecture, Kass described his life as a pursuit of what it truly means to be human. In his search for answers about deeper meanings of humanity Kass has studied great literature and kept abreast of cutting-edge bioscience. He has been honored with many awards, and published numerous books and articles. But perhaps what is more significant than these things is the relationship he has demonstrated between humanities and biology, and the influence he has had on national policy, his peers, his students, and his fellow citizens.


  1. Adelman, Ken. “Biotechnology and Stem-Cell Research: Interview with Dr. Leon Kass.” The Washingtonian, November 1, 2005, Health section. http://www.washingtonian.com/sections/health/index.html
  2. Berkowitz, Peter. “The Pathos of the Kass Report.” Policy Review 115 (2002): 1–7.
  3. Kass, Leon R. “Looking for an Honest Man.” National Affairs 1 (2009): 160–80.
  4. Leon Kass, interview with the American Enterprise. “’Live’ with Leon Kass.” The American Enterprise Institute for Public Policy Research. http://www-news.uchicago.edu/citations/06/060612.kass-tae.html (Accessed February 17, 2010).


How to cite

Philbrick, Samuel, "Leon Richard Kass (1939- )". Embryo Project Encyclopedia ( ). ISSN: 1940-5030 https://hdl.handle.net/10776/2304


Arizona State University. School of Life Sciences. Center for Biology and Society. Embryo Project Encyclopedia.

Last modified

Monday, September 11, 2023 - 10:58

Share this page