Kai Nielsen (born 1926) is the Professor Emeritus of Philosophy at the University of Calgary and Adjunct Professor of Philosophy at Concordia University, Montreal. He holds a Ph.D. from Duke University (1959) and a B.A. from the University of North Carolina. He is the author of Ethics Without God, as well as other works on analytical philosophy, atheism and Marxism. He specializes in metaphilosophy, contemporary ethical and political theory and Marxism.
- The Craig-Nielsen Debate: God, Morality, and Evil. February 1991, University of Western Ontario. Complete debate online at Christian Leadership Ministries.
- Globalization and Justice. Amherst, New York: Humanity Books, 2002. ISBN 1-5910-2054-9
- Naturalism and Religion. Amherst, New York: Prometheus Books, 2001. ISBN 1-5739-2853-4
- Naturalism Without Foundations. Amherst, New York: Prometheus Books, 1996. ISBN 1-5739-2076-2
- After the Demise of the Tradition: Rorty, Critical Theory and the Fate of Philosophy. Boulder, Colorado: Westview Press, 1995. ISBN 0-8133-8044-8
- Marxism and the Moral Point of View. Boulder, Colorado: Westview Press, 1989. ISBN 0-8133-0653-1
- Equality and Liberty: A Defense of Radical Egalitarianism. Totowa, New Jersey: Rowman and Allenheld, 1985. ISBN 0-8476-7516-5