John Rawls was the most influential political philosopher in the second half of the 20th century, and his book A Theory of Justice has been described as the most significant work in political philosophy since the writings of John Stuart Mill.

Since its publication in 1971, Rawls’s works have established the main stream of Anglo-American political philosophy. A Theory of Justice has sold more than a quarter million copies in English, and has been translated into more than 20 languages. Only ten years after it was published, a bibliography of articles on Rawls contained more than 2,500 entries. Since then, this number has more than doubled.

Rawls’s lifelong interest in justice developed out of his concern, while a student and soldier during the war, with the basically religious questions of why there is evil in the world and whether human existence is nonetheless redeemable. This led him to inquire whether a just society is realistically possible on earth. His life’s work was directed towards discovering what justice requires of us, and showing that it is within human capacities to realise a just society and a just international order.

John Rawls was born in Baltimore, Maryland, the second of William and Anna Rawls’s five sons, two of whom died in childhood. He grew up in Baltimore, where his father practised law. After high school — the Kent School in western Connecticut — Rawls entered Princeton University in 1939. There he was introduced to political philosophy by Norman Malcolm, a student of Wittgenstein.

On graduating in 1943, Rawls joined the US Army as a private, and after initial training he was sent to fight in the war in the Pacific, in New Guinea, the Philippines, and eventually in Japan.

After his military service he began his graduate studies in philosophy at Princeton in 1946, writing his dissertation on moral knowledge and judgments on the moral worth of character. After teaching for two years, he went to Oxford on a Fulbright scholarship for the academic year 1952-53, and was affiliated to Christ Church. This year at Oxford was one of the most formative of his long career. He was especially influenced by lectures of H. L. A. Hart on the philosophy of law, as well as by seminars held by Isaiah Berlin and Stuart Hampshire.

Rawls returned to America in 1953, going to Cornell University as assistant professor of philosophy. There he joined his former teacher Norman Malcolm on the faculty, as well as his former Princeton classmates and lifelong friends, Rogers Albritton and David Sachs. He stayed at Cornell until 1959, when he visited Harvard for a year before joining the faculty at Massachusetts Institute of Technology. Two years later he took a position at Harvard, where he remained a member of the standing faculty until his retirement in 1991 (though he continued teaching until 1995).

Rawls’s lectures on the history of moral philosophy were so popular that in the 1970s, two weeks after the start of one course, he decided to help the undergraduates and graduate students who were frantically taking verbatim notes, and offered to make copies of his lectures available to them. The first batch of handwritten notes cost 40 cents. He continued to update the lectures until 1991, and they were finally edited for publication by Barbara Herman in 2000.

From the outset of his career Rawls’s work was guided by the question, “what is the most appropriate moral conception of justice for a democratic society?” In A Theory of Justice this question was pursued as part of a general investigation into the nature of social justice. Rawls aimed to redress the predominance of utilitarianism in modern moral and political philosophy.

Utilitarianism had grown out of the work of the British empiricists, starting with David Hume, and has been the most influential moral conception for more than 250 years. Utilitarianism says that laws are just when they promote the greatest overall happiness of the members of society. But issues of just distribution have long been seen as problematic for utilitarianism, which seems to condone sacrifices of individual and minority welfare for the sake of the majority. Yet a compelling alternative conception of justice seemed to be lacking in moral philosophy.

To develop such an alternative, Rawls turned to the liberal and democratic, “social contract” traditions of Locke, Rousseau and Kant. According to social contract doctrine, laws are just when they could be agreed to by free persons from a position of equal right. This has the consequence that, to be just, laws must benefit not just a majority, but everyone, so promoting the common good. A further consequence of Rawls’s social contract view is that justice generally requires that basic social goods — liberty and opportunity, income and wealth, and the bases of self-respect — be equally distributed, unless an unequal distribution is to everyone’s advantage.

Under the favorable social conditions of modern societies, a special conception, “justice as fairness”, applies, and this requires that priority be given to certain liberties and fair opportunities via the institutions of a liberal constitutional democracy. Rawls’s principles of justice require that certain liberties (liberty of conscience and freedom of thought, political liberties, freedom of association and so on) be equally provided for and treated as more important than other rights and liberties; that these basic liberties be given priority over aggregate social good and perfectionist values; that “fair” opportunities be equally provided for all citizens; and that differences in income and wealth and in social positions be structured so as maximally to benefit the worst-off members of society.

Rawls’s second book appeared in 1993. The leading idea of Political Liberalism is that in any free society, reasonable, fair-minded people are inevitably going to have different and conflicting religious, philosophical and moral views. This poses a problem since ideally a liberal constitutional democracy requires that the laws be justifiable to everyone if they are to be free and accorded due respect. How is this ideal possible if citizens do not share a common moral or religious view? Rawls no longer takes issue directly with utilitarianism or other moral conceptions. Instead he tries to show how democratic citizens with diverse moral and religious views can all affirm the same “freestanding” liberal conception of justice on the basis of “public reason”.

Rawls’s third major book, on justice between nations, appeared in 1999. In The Law of Peoples he developed an account of international justice that denies that the sovereignty of nations allows them to persecute their own people. Just and decent nations, he argues, have a right to intervene to protect the persecuted peoples of “outlaw states”. Moreover, all nations have a duty to assist impoverished nations so that they may become self-sufficient. Rawls also condemned the American bombing of Japanese cities, especially the nuclear attacks on Hiroshima and Nagasaki, and the Allied bombing of German cities during the Second World War, as violations of the human rights of civilians.

In 1999 Rawls’s Collected Papers and a revised edition of A Theory of Justice were published. His Harvard lectures on Kant, Leibniz, Hume and Hegel, and those on his own work, Justice as Fairness: A Restatement, have also been published in the past two years.

At Harvard, Rawls occupied the John Cowles Chair in Philosophy until 1979, when he succeeded Kenneth Arrow as James Bryant Conant University Professor. In 1999 he was awarded a National Humanities Medal by President Clinton. He was awarded the Rolf Schock Prize in Logic and Philosophy the same year, and held honorary degrees from Oxford and Harvard.

A quiet, witty, and modest man, Rawls taught and influenced a great many of America’s best-known contemporary philosophers. He was a private person who spent his time either at his work or with his family and close friends. He regularly declined requests for interviews, and chose not to take an active role in public life. He conscientiously avoided celebrity status, believing that philosophers are usually misunderstood when they address the public, and that while philosophy has a considerable influence on political life, that influ- ence is indirect, taking many years to become a part of a community’s moral consciousness.

In his later years Rawls was increasingly interested in history, particularly books on the Second World War and on Abraham Lincoln, whom he especially admired as a statesman who did not compromise with evil. These interests are evident in Rawls’s late works on justice between nations.

John Rawls married Margaret Warfield Fox of Baltimore on her graduation from Pembroke College (now part of Brown University) in 1949. She survives him, along with their two sons and two daughters.

John Rawls, philosopher, was born in Baltimore, Maryland, on February 21, 1921. He died in Lexington, Massachusetts, on November 24, 2002, aged 81.