For many progressives, it was a big moment. In 2019, Congress was holding its first hearing on whether the United States should pay reparations for slavery.

To support the idea, Democrats had invited the influential author Ta-Nehisi Coates, who had revived the reparations issue in an article in The Atlantic, and the actor and activist Danny Glover.

Republicans turned to a virtual unknown: a 23-year-old philosophy major at Columbia University, Coleman Hughes.

In the hearing, Mr. Hughes, looking very much his age, testified to the House subcommittee that not paying reparations after the Civil War was “one of the greatest injustices ever perpetrated.”

But, he continued, they should not be paid now. “There’s a difference between acknowledging history and allowing history to distract us from the problems we face today,” he said, pointing to endemic problems that affect Black Americans, such as poor schools, dangerous neighborhoods and a punitive criminal justice system.

Some in the audience booed. The Democratic subcommittee chairman, Steve Cohen of Tennessee, pleaded for calm — “chill, chill” — but then suggested that Mr. Hughes’s testimony had been presumptuous.