They called him the midget Euclid and baby Einstein. In 1944, The New York Times said he lisped in logarithms. For a time, during World War II and its aftermath, Joel Kupperman was one of the most famous children in the country and also one of the most loathed.

From 6 to 16, Kupperman was a star on “The Quiz Kids,” a thunderously popular radio program that later migrated to television. He captivated Marlene Dietrich and Orson Welles by performing complex math problems, joked with Jack Benny and Bob Hope, charmed Eleanor Roosevelt and Henry Ford. He played himself in a movie (“Chip Off the Old Block,” in 1944), addressed the United Nations and was held up as an exemplar of braininess to a generation of children. (Hence all the loathing.)

But his early fame became a taboo subject for his family in his adulthood, most of which was spent teaching philosophy at the University of Connecticut.

“It was something we knew we were not ever to mention,” said Karen Kupperman, his wife of 56 years and a history professor at New York University. “If someone brought up the ‘The Quiz Kids,’ or even television, he would walk away.”

In a rare interview with The New York Times in 1982, Kupperman said his memories of being a national sensation were painful. “Being a bright child among your peers was not the best way to grow up in America,” he said.

He died April 8 at an assisted living facility in the Brooklyn borough of New York City. He was 83. His wife said he had struggled with dementia for years. His death certificate lists an “influenza-like illness (probably COVID-19)” as the cause, she said.

Originally broadcast from Chicago and sponsored by Alka-Seltzer and One A Day vitamins, “The Quiz Kids” aired every Sunday night. For a while Kupperman was the youngest and, because of his lisp, the most adorable of its contestants, precocious boys and girls who fielded questions about math, literature, sports and history, all sent in by listeners.

The Quiz Kids toured the country selling war bonds and, perhaps, an appealing image of Jewish children, as Kupperman suggested to his son, Michael, a comic artist and illustrator, although not all of the children were Jewish. They were paid in war bonds, one per appearance, and a war bond was the price of admission for the studio audience. (By the end of the war, the children had sold bonds worth an estimated $120 million — about $1.7 billion in today’s money.)

In her 1982 memoir “Whatever Happened to the Quiz Kids? Perils and Profits of Growing Up Gifted,” Ruth Duskin Feldman, the show’s literature buff (she died in 2015), noted the rampant anti-Semitism of the time. “When we moved through crowds,” she wrote, “there were loud remarks of ‘Oh, they’re all Jews!’”

The show moved to television after the war, and the cameras did not favor a maturing Kupperman, who stayed on until he was 16, the dutiful son to a controlling stage mother, Michael Kupperman said.

Although the producers brought in younger and cuter children to field questions, Joel Kupperman’s hand was always up, sometimes blocking the faces of the smaller children, which didn’t make for riveting TV, as Michael Kupperman put it — a spectacle made only worse by Joel Kupperman’s robotic demeanor, which made him seem priggish.

And then it was over: 10 years of Kupperman’s life, nearly his entire childhood, meted out in 400 episodes. (The program, which ended in 1953, except for a brief run in 1956, largely escaped the quiz show scandals of the time, although Joel Kupperman’s mother later said that the producers had known of his interests and had tailored questions to them.)

“All of us on the program experienced to some degree ‘child star letdown,’ but we remembered the actual experience fondly,” Richard Williams, the show’s other math whiz, now a retired diplomat, said in a phone interview. “It was a high for us. But Joel said it destroyed his childhood. When he was 6, I was 11. The program put stress on the smallest kids. They got the most attention and were the least equipped to deal with it.”

He added: “Once the show went on television they kept Joel, because he was so well known, but the general age got lower and lower. I’m guessing that experience was pretty sour for him. No real competition and no real comradeship.”

Joel Kupperman was bullied at the University of Chicago, which he entered at 16. He studied math and was introduced to Asian philosophy and found a mentor in a visiting professor, who told him, as Karen Kupperman said, “You need to leave the country.”

Joel Kupperman earned a Ph.D. in philosophy from the University of Cambridge in England and joined the philosophy department of the University of Connecticut in 1960, remaining there until his retirement in 2010. His scholarly focus was on ethics and aesthetics, and he was an early champion of Asian philosophy at a time when Eastern traditions were considered more akin to religion or mysticism than philosophy.

Kupperman wrote several books on philosophy, including “Character” (1991) and “Six Myths About the Good Life: Thinking About What Has Value” (2006).

“He started out writing about pure ethics,” his daughter, Charlie Kupperman, said, “but as his career went on, he was trying to understand character, and why it’s so hard for people to be good.”

Joel Jay Kupperman was born May 18, 1936, in Chicago to Solomon and Sara (Fischer) Kupperman. His father was a civil engineer, his mother a homemaker. Joel Kupperman’s older sister was also briefly a Quiz Kid.

There was so much mythmaking around the show, Michael Kupperman said, that it’s hard to know with any conviction what parts of Joel Kupperman’s story are true. It is a fact that as a toddler he was taught math by his father, and Joel Kupperman may indeed have lulled himself to sleep by singing the multiplication tables, but he probably did not use a beaded toy on his crib as an abacus, or catch a grocer cheating on a bill. On the other hand, it’s quite possible that he spotted errors in an early math textbook, and it’s fairly certain that a kindergarten teacher suggested that his parents reach out to “The Quiz Kids” producers.

He met Karen Ordahl in Cambridge, Massachusetts, after she had earned a master’s degree in history at Harvard University, and they married in 1964, settling down together in Storrs, Connecticut, near the University of Connecticut campus.

In addition to her and his children, he is survived by his sister, Harriet Moss, and a grandson.

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