The realities of a moment in which recurring episodes of police brutality present themselves as modern day lynchings would seem to make a project like Mr. Bell’s especially purposeful, but the parks department did not embrace his proposal. In an email to the league, Jennifer Lantzas, the agency’s deputy director of public art, expressed apprehension on the part of staff members that “the image of the noose could be problematic for the borough.” Mr. Bell’s design was rejected. Sam Biederman, a spokesman for the department, told me in an email that the decision was based on a concern among parks officials that the proposed site “is adjacent to an area regularly programmed with passive recreational activities such as yoga, Pilates and senior movement.”

Precisely when it became civic policy to guard the potential sensitivities of grown women in Lululemon is unclear, but the fate of Mr. Bell’s project, reported last week by The West Side Rag, illustrates the ways in which a culture of emotionally protectionist politics has swelled beyond the world of Oberlin and Yale. Mr. Bell argued for his original idea in writing, but his repeated requests to speak to city officials in person were ignored. The theme for the Model to Monument exhibit this year was the public square and its responsibilities. “My interpretation of that idea is a place where people interact for the benefit of social conscience and justice,” he said. “I knew that I wanted to do a piece that would introduce a dialogue. The piece I designed is about humanity against hatred.”

Forced to replace the noose with something else, Mr. Bell is evoking a large mouth instead, but he is not happy about it. “The mouth is simply a resolution to satisfy members of the parks department,” he told me.

Mr. Bell’s upbringing in Mount Vernon, N.Y., as the son of a prominent musician — his father was the jazz bassist Aaron Bell, who played with Duke Ellington and had a doctorate in education — did not shield him from the miseries of racial inequality. When he was a student at Pratt Institute in Brooklyn in 1968, the younger Mr. Bell was beaten up on Halloween night by a gang of white teenagers who struck him at the base of his skull with a metal bar. (A report in The Daily News about the attack described him as having been put on the “serious list” at Brooklyn Hospital.) At the time, members of Pratt’s Black Students Union complained about the failure of the police to arrest anyone five days after a report had been filed and descriptions of some of the assailants provided. Mr. Bell said he had seizures for years after the attack. Once, on his way to see his father play at the La MaMa theater, a seizure left him passed out on the sidewalk. A police car deposited him on the steps of Bellevue Hospital Center, with all the money in his wallet removed, he said.