Finnis was educated at the University of Adelaide, where he was a member of St. Mark's College. He obtained his LL.B. there, winning a Rhodes scholarship to University College, Oxford, in 1962, where he obtained his D.Phil. for a thesis on the concept of judicial power, with reference to Australian federal constitutional law.

Finnis is one of the most prominent living legal philosophers. His work, Natural Law and Natural Rights, is regarded as one of the definitive works of natural law philosophy, Oxford University Press: Natural Law and Natural Rights: John Finnis drawing both on Oxonian and Catholic Thomistic philosophical tradition to challenge the dominant Anglo-positivist approach to legal philosophy taken by John Austin and H.L.A. Hart.

Stephen Buckle writes that Natural Law and Natural Rights defends the following basic human goods: life, knowledge, play, aesthetic experience, sociability (friendship), practical reasonableness, and religion, the last being defined as "all those beliefs that can be called matters of ultimate concern; questions about the point of human existence." Buckle sees Finnis's list of proposed basic goods as plausible, but notes that "Finnis's account becomes more controversial when he goes on to specify the basic requirements of practical reasonableness." He sees Finnis's requirement that practical reason requires "respect for every basic value in every act" as intended both to rule out consequentialism in ethics and also to support the moral viewpoint of the Catholic Church on a range of contentious issues, including contraception and masturbation, which in his view undermines its plausibility.

Craig Paterson writes that Finnis's work on natural law ethics has been a source of controversy in both neo-Thomist and analytical circles. Paterson sees Finnis's work as interesting because it challenges a key assumption of both neo-Thomist and analytical philosophy: the idea that a natural law ethics must be based upon an attempt to derive normative (or "ought") statements from descriptive (or "is") statements.

Political commentator Andrew Sullivan writes that Finnis has articulated "an intelligible and subtle account of homosexuality" based on the new natural law, a less biologically based version of natural law theory. In his view, Finnis argues that the state should deter public approval of homosexual behavior while refusing to persecute individuals on the basis of their sexual orientation, basing this position not on the claim that homosexual sex is unnatural but on the idea that it cannot involve the union of procreation and emotional commitment that heterosexual sex can, and is therefore an assault on heterosexual union. Sullivan believes that such a conservative position is vulnerable to criticism on its own terms, since the stability of existing families is better served by the acceptance of those homosexuals who are part of them.

Books

• Aquinas: Moral, Political and Legal Theory (Oxford University Press 1998).
• Moral Absolutes: Tradition, Revision and Truth (Catholic University of America Press 1991).
• Natural Law, 2 vols (as editor) (New York University Press 1991).
• Nuclear Deterrence, Morality, and Realism, with J. M. Boyle Jr. and Germain Grisez (Oxford University Press 1987).
• Fundamentals of Ethics (Georgetown University Press and Oxford University Press 1983).
• Natural Law and Natural Rights (Oxford University Press 1980; 9th impression. 1997).

Articles

• Aquinas' Moral, Political and Legal Philosophy
• Natural Law: The Classical Tradition PDF
• The Priority of Persons PDF
• Economy or Explication? Telling the Truth About God and Man in a Pluralist Society PDF
• The Good of Marriage and the Morality of Sexual Relations PDF
• Law, Morality and "Sexual Orientation" PDF

Video lectures

• Secularism
• God and Man
• Practical Reason