Moynihan, who wrote or edited a total of 18 books, was well-known for his studies of American race relations.

In a 1965 report to President Lyndon B. Johnson titled “The Negro Family: The Case for National Action,” commonly known as the “Moynihan Report,” Moynihan pointed to the increase in the number of single-parent families as a fundamental reason for poverty and instability in African-American communities.

The report earned him the wrath of civil rights leaders who accused him of racism. Those accusations would dog him through his first senate race in 1976, when he defeated veteran Republican Senator James L. Buckley. He was re-elected three times.

In a statement, University President Lawrence H. Summers remembered Moynihan as a man “at the center of national and international debate on some of the most important and difficult issues of our time,” who “made profound contributions both to the life of the mind and the life of the nation.”

John Rawls

John Rawls, Conant professor emeritus and one of the most influential political and moral philosophers of the 20th century, died at his home in Lexington on Nov. 24, 2002. He was 81.

Rawls is credited with reviving the social contract tradition in philosophy, and his magnum opus, A Theory of Justice, is considered a staple of undergraduate reading lists.

It argues persuasively for a political philosophy based on equality and individual rights. It describes the reconciliation of liberty and equality, concepts that were viewed as fundamentally at odds for much of the 20th century.

“His achievement in moral and political philosophy is certainly the largest achievement in the English-speaking world since John Stuart Mill’s,” said MIT Professor of Social and Political Philosophy Joshua Cohen, whose dissertation was advised by Rawls.

Bass Professor of Government Michael J. Sandel remembered Rawls as “a quiet but towering voice for a more tolerant and generous way of organizing modern democratic societies.”

“In my first year as a young assistant professor at Harvard, the phone in my office rang,” Sandel wrote in an e-mail. “The voice on the other end said, ‘This is John Rawls, R-A-W-L-S.’ It was as if God himself had phoned to invite me to lunch, and spelled his name just in case I didn’t know who he was.”

A month before his death, Rawls became the second living philosopher to have a Cambridge Companion volume published on him.

In 1997, Harvard awarded Rawls an honorary Doctor of Laws degree and two years later President Clinton and First Lady Hillary Rodham Clinton presented him with the National Humanities Medal in a special ceremony at the White House.

Rawls held the post of assistant and associate professor of philosophy at Cornell from 1953 to 1959 and professor of philosophy at MIT from 1960 to 1962.