Sister Mary Prudence Allen RSM (born 21 July 1940) is an American philosopher who converted to Catholicism and joined the Religious Sisters of Mercy. In 2014 she was appointed to the International Theological Commission for a five-year term by Pope Francis. Her areas of specialization include the history of philosophy, philosophical anthropology, philosophy of woman, existentialism, and personalism. Areas of competence include metaphysics, philosophy of God, epistemology and logic.

Allen was born Christine Hope Allen in Oneida, New York, on July 21, 1940. In 1962, she graduated with a B.A in philosophy cum laude from the University of Rochester in New York. She completed one year of graduate study, while serving as Residence Director at State University of New York at Buffalo. Having received a full tuition scholarship from Claremont Graduate School, she moved to California in 1963. She joined the Catholic Church in 1964 and married one year later. In 1967, she earned her doctorate in philosophy from the Claremont Graduate School. During this time, she and her husband had two sons, whom she helped raise while teaching philosophy as an assistant professor (1969–1977) at Concordia University in Montreal, Quebec, Canada, when it was still called Sir George Williams University. Meanwhile, her marriage was annulled in 1972. She was promoted to associate professor of philosophy (1977–1993). In 1983, she was accepted into the novitiate of the Religious Sisters of Mercy. She took perpetual vows in 1990.^[1]

While at Concordia, Sister Allen received almost yearly grants from the Social Sciences and Humanities Research Council of Canada for her work in the conceptual history of women (1979–1995); these totaled $187,699. She also team taught an introductory course in woman studies, and she received innovative teaching development grants. Concordia University promoted her to full professor in 1993, and she continued teaching until 1996, when she retired as a Distinguished Professor Emerita.

In 1998, she moved to Denver to develop the philosophy program at Saint John Vianney Seminary. From 2000 to 2003, she was the founding chair of the Seminary's philosophy department. At this time, she began developing materials for ENDOW (Educating on the Nature and Dignity of Woman). In 2004, she began an eleven-year appointment as a full professor in this newly formed department. She was also appointed Consultant to the Pontifical Council for the Laity in a Study Seminar on "Men and Women: Diversity and Mutual Complementarity." In 2005, she began a nine-year term serving on the St. Thomas Advisory Committee for Women, Culture, and Society Program at the University of St. Thomas in Houston, Texas. In 2008, she served as a Consultant to Rome John Paul II Institute on Gender Identity Issues. From 2011 to 2014, when she retired, she held the Charles J. Chaput Endowed Chair of Philosophy, at St. John Vianney Theological Seminary, Denver, Colorado. From 2014–2016, she was the Bishop's Archivist for the Diocese of Lancaster, England. Also, in 2014, at the invitation of Pope Francis, she began a five-year term serving on the International Theological Commission with four other women (prior to this only two women had served on this commission).^[2] During that term, she helped author "Sinodality in the life and mission of the Church".^[3]

Allen has stated that she considers herself a New Feminist philosopher, citing the influence of Pope John Paul II on her writing. She describes feminism as type of humanism and coined the term "personalist feminism."^[4] The philosophy of the human person and of human community is a major focus of her writing. She agrees with Aristotle's understanding of the relationship between soul and body, as well as his approach to science, but opposes his view that human males are superior to females. Like other feminists, she wants to eliminate the discrimination and violence that many women face, but, as a New or Personalist Feminist, she opposes abortion.^[5] She also argues that gender identity is properly based on sex, that there is a conflict between gender reality and gender ideology, and that gender reality needs to be regained.^[6]

Allen's three-volume magnum opus, The Concept of Woman, is the culmination of a lifetime of the scholarly investigation into how womanhood has been understood throughout the history of philosophy. Allen argues that there has been a true development in the understanding of gender leading to integral complementarity. This understanding builds upon the thought of Aristotle and Augustine. She discusses three understandings of gender throughout history: gender polarity, gender unity, and gender complementarity. Gender polarity can appear either in its traditional form, in which men are considered superior to women, or in a reversed form, in which women are seen as superior. In its traditional form, gender polarity became dominant in philosophical circles for centuries under the influence of Aristotle. Gender unity holds that there are no significant differences between men and women. Gender complementarity can appear in one of two forms—fractional complementarity, in which men and women form two halves of a whole, and integral complementarity, in which men and women are whole on their own and together form something greater than two wholes.^[7] Allen holds to the integral complementarity position.^[8]

• 1962 – Fanny R. Bigelow Award to the Graduating Senior Woman who had contributed the most leadership to the University of Rochester, Rochester,
• 1972 – First prize, Fredonia University Philosophical Essay Contest for "Woman and Persons", New York State.
• 1973 – Sir George Williams University Student Life Award for Outstanding Contribution to quality of Student Life, Montreal, Quebec, Canada.
• 1988 – Air Canada West Island Chronicle Heart of Gold Award for Contribution to Public Service, Montreal, Quebec, Canada
• 2003 – Thomas Aquinas Medal, University of Dallas, January 28
• 2003 – Shared 2003 Second Place Award for Gender Issues by the Catholic Press Association of the United States and Canada with Eerdmans, Publisher  for The Concept of Woman: Vol. II — The Early Humanist Reformation 1250–1500.
• 2004 – The Cardinal Wright Award, Fellowship of Catholic Scholars, September 25, Pittsburgh, PA.
• 2005 – Shared 2005 Third Place Award for Gender Issues by the Catholic Press Association Book Award with Eerdmans, Publisher and Michele Schumacher, ed., for two chapters in Women in Christ.
• 2008 – Doctor of Humane Letters, Honoris Causa, in recognition of her contributions to the intellectual life of the Church on the nature and dignity of women, St Charles Borromeo Seminary, Overbrook, Wynnewood, Pennsylvania, May 22, 2008.
• 2012 – Inaugural Annual Humanitarian Leadership Award, Siena Symposium, St. Thomas University, St. Paul, Minnesota, April 23, 2012.
• 2014 – Scholarly Excellence Award, American Maritain Association, Providence Rhode Island.
• 2017 – Sixth Annual Human Dignity Lecture, McGrath Institute for Church Life and the Office of Human Dignity and Life Initiatives at the University of Notre Dame, South Bend, IN.^[9][10][11]
• 2018 – University of Notre Dame's McGrath Institute for Church Life held a day-long conference to celebrate the completion of Allen's Concept of Woman trilogy.^[12][13][14]
• 2021 – Aquinas Medal, American Catholic Philosophical Association, St. Louis, MO^[15]

All papers are archived at Concordia University Archives in Montreal^[16]