Abigail Thernstrom, a social scientist whose colorblind remedies for racial disparities in educational achievement, voting and employment elevated her from a former red-diaper baby into a leading skeptic of affirmative action programs, died on April 10 in Arlington, Va. She was 83.

The cause was multiple organ failure after Dr. Thernstrom had lapsed into a coma a week earlier, her daughter, Melanie Thernstrom, said.

Raised in a community of Communist fellow-travelers, Dr. Thernstrom became as an adult a tenacious foe of affirmative action, gerrymandering to create minority districts, and other measures to foster racial preferences.

She marshaled those arguments in her first book, “Whose Votes Count?: Affirmative Action and Minority Voting Rights” (1987), and amplified them in “America in Black and White: One Nation Indivisible” (1997), which she wrote with her husband, the Harvard historian Stephan Thernstrom.

Her neoconservative voice reverberated in public appearances, through think-tank publications and as President George W. Bush’s appointee to the United States Commission on Civil Rights in 2001.

Her ascendancy coincided with other currents: a backlash against black and Hispanic protest groups and politicians who demanded equal rights while, in the eyes of their critics, refusing to acknowledge the gains that had been achieved; and a longing by many white people to proclaim that the “American Dilemma” — as the economist Gunnar Myrdal characterized widespread racial inequality in 1944 — had largely been resolved.

To close the gaps in opportunity that remained, Dr. Thernstrom argued for educational alternatives like vouchers and charter schools and holding students to higher standards. Admitting students on the basis of racial preferences can stigmatize minority students and dilute the value of their diplomas, she contended.

She insisted that more and more, whites would vote for black and Hispanic candidates, and that creating majority-minority districts only marginalized their impact on public policy while empowering white-dominated districts that outnumber them.

If racial preferences were ever a remedy for reducing disparities, she and her husband maintained, they were no longer necessary.

“We do not say that they make no difference whatsoever,” Dr. Thernstrom told The New York Times in 1998. “We do say that they haven’t made as much difference as is widely attributed to them, and that they carry with them a very high cost. When it comes to race, the test of any public policy is, Will it bring us together or divide us? Preferences flunk that test.”

Dr. Thernstrom argued that while she had sung along with Pete Seeger as a girl and in 1972 voted for George McGovern over Richard M. Nixon, she hadn’t become a convert from liberalism. (She voted for a Republican for president for the first time in 1992, picking George H.W. Bush over Bill Clinton.)

Instead, she said, she had consistently heeded the Rev. Dr. Martin Luther King Jr.’s gospel that people should be judged by the content of their character, not by the color of their skin.

Reviewing “America in Black and White” for The Atlantic Monthly, the conservative economist Glenn C. Loury wrote that the Thernstroms’ exhaustive study “tells hard truths unsparingly.” But he also said that it lacked “an appreciation of irony, and a sense of the tragic.”

“Being right about liberals’ having been wrong is an accomplishment, to be sure, but it is no longer good enough,” Professor Loury wrote, adding that the book “contains insights deserving a wide reading, along with unfounded speculations that, in my opinion, are best ignored.”

Other critics invoked President Lyndon B. Johnson’s analogy from 1965 that fairness is not merely taking “a person who, for years, has been hobbled by chains and liberate him, bring him up to the starting line of a race, and then say, ‘You are free to compete with all the others.’”

The political scientist Andrew Hacker also found fault with their argument, telling The Times, “Here are two white people who are essentially lecturing black Americans, saying: ‘What are you complaining about? Stop your griping. Here are the data. You’re better off than ever before.’”

But Dr. Thernstrom had her champions. In a tribute after her death, Jason L. Riley, a member of The Wall Street Journal editorial board and an African-American, wrote in The Journal that she had revealed “inconvenient truths” to civil rights activists when “civil rights battles for blacks have been largely fought and won.” She had, he wrote, “put intellectual honesty ahead of political correctness.”

Abigail Mann was born on Sept. 14, 1936, in Manhattan to Ferdinand and Helen (Robinson) Mann. Both parents had rejected the Orthodox Judaism of their upbringing. Her father, a Communist, was a failed businessman who helped run Finney Farm, a struggling cooperative in Croton-on-Hudson, N.Y. Her mother later moved to Europe, where she was active in the modernist Bauhaus art movement. She returned to New York to escape Naziism and died when Abigail was a teenager. Her father then married the sculptor Dorothy Dehner.

After graduating from the progressive Little Red School House and Elisabeth Irwin High School in Greenwich Village, Abigail attended Reed College in Oregon before transferring to Barnard College in New York, where she earned a bachelor’s degree in European history in 1958.

She enrolled in a master’s program in Middle Eastern studies at Harvard but switched to constitutional law, with an emphasis on civil rights, after becoming smitten with an American history major, Stephan Thernstrom. They had met on a blind date (attending a lecture by the progressive journalist I.F. Stone) and married about two months later.

While her husband taught at the University of California, Los Angeles, and then returned to teach at Harvard in 1973, she took off 15 years to raise their two children, both of whom attended public schools.

She completed her doctorate at Harvard in 1975 and began teaching there.

In addition to their daughter, Melanie, an author, Dr. Thernstrom is survived by her husband, with whom she lived in McLean, Va.; their son, Samuel, who founded a nonprofit alternative energy organization; and four grandchildren.

Dr. Thernstrom and her husband also wrote “No Excuses: Closing the Racial Gap in Learning” (2003). She was a member of the Massachusetts State Board of Education for more than a decade, vice chairwoman of the U.S. Civil Rights Commission from 2010 to 2012; a senior fellow at the Manhattan Institute in New York; and an adjunct scholar at the American Enterprise Institute in Washington.

Michael Yaki, a former campaign official for Barack Obama, called Dr. Thernstrom “my closest friend on the commission” and said, “Despite the fact that our views could be, in her words, miles apart, we also shared a commitment to the ongoing mission of the commission and often found common ground.”

Although her books became conservative bibles, her voting record on the rights commission was often nonpartisan, and she bridled at being pigeonholed ideologically.

“At the end of the day, I’m me, and I can’t be anybody else,” she said.

And being herself meant holding fast to her views on race.

“Race is the American dilemma,” she told the PBS series “Frontline” in 2016. “It is race that, you know, keeps this country in agony. It is our most serious domestic problem. And therefore, we want to think specially hard about anything that involves sorting people out on the basis of one drop of blood of this or that.”