His wife, Barbara Boggs Sigmund, was mayor of Princeton from 1984 to her death at age 51 in 1990.
Born in Philadelphia, Mr. Sigmund earned a bachelor's degree, summa cum laude, at Georgetown University in 1950, studied on a Fulbright scholarship in 1950-51 at the University of Durham, England, and earned a master's at Harvard University in 1954 and a doctorate there in 1959, where, his resumé states, his "dissertation was awarded a prize as best thesis."
In 1956-57, as a lieutenant, he was a political analyst at the European headquarters of the Air Force in Wiesbaden, Germany.
Mr. Sigmund was director of the Latin American Studies Program at Princeton in 1969-70 and for several terms in the 1980s and 1990s.
George Kateb, who retired in 2002 as a Princeton professor of politics, said it was "unusual for any person" to have two fields of concentration in any subject, as Mr. Sigmund did with the study of political principles and of Latin American politics.
"He was most famous for his work in what used to be called liberation theology," Kateb said.
That movement within the Roman Catholic Church, he said, "was to give a presence to the conditions of the poor," but was "quite unpopular" with the church hierarchy, which eventually silenced the movement.
Mr. Sigmund was "a devout Catholic," Kateb said, who was "the kind of conservative who knew that you are able to conserve only by changing and meeting the demands that deserve to be met."
Among Mr. Sigmund's several books, Liberation Theology at the Crossroads: Democracy or Revolution was published by Oxford University Press in 1990.
"I've never known anyone to be so engaged in so many activities, scholarly and not scholarly, and to keep so calm throughout his life," Kateb said.
Among his several appointments, Mr. Sigmund was a fellow at the Woodrow Wilson International Center for Scholars in Washington in 1985-86.
"In his spare time," brother Peter said, Mr. Sigmund "was a fund-raiser for Haiti," specifically for the Rev. Thomas Hogan, a former Catholic chaplain at Princeton working to feed and educate poor children there.
Besides his brother, Mr. Sigmund is survived by sons Stephen, David, and Paul IV; another brother; two sisters; and four grandchildren.
A visitation was set from 6 to 9 p.m. Thursday, May 1, at the Stuart Country Day School of the Sacred Heart, 1200 Stuart Rd., Princeton. A Funeral Mass was set for 1:30 p.m. Friday, May 2, at the Princeton University Chapel. Burial is to be in Princeton Cemetery.
Donations may be sent to www.handstogether.org. Condolences may be offered to the family at http://thekimblefuneralhome.com.