Is [school desegregation] chiefly a movement to abolish a caste system? Is it at heart actually a class struggle intensified by racism? Should it be measured strictly in constitutional terms? By educational yardsticks? By how much it may unite or separate the races? By its importance as the centerpiece on which many other civil rights gains have been balanced? By some combination of these elements?

Noel Epstein, my former Post colleague, wrote those words nearly 29 years ago in an article in which he tried to assess the impact of busing to achieve racial desegregation in public schools. His point: You can't hope to reach consensus on an answer unless you can agree on what the question is.

Epstein's admonition is worth recalling today as America takes note of the 50th anniversary of the Supreme Court decision that outlawed school segregation.

How much better off are we as a society as a result of that decision?

"It's too simplistic to say, as some are saying, that it 'didn't work,' " Theodore Shaw, the new director-counsel of the NAACP Legal Defense and Educational Fund, said over a recent lunch. "It worked to end legal school segregation, and I think you'd agree that's a good thing. It helped launch the modern civil rights movement, and at least some of the desegregation, not just in schools but in all walks of life, is directly traceable to Brown v. Board of Education."

Shaw, who was born six months after the decision came down, says the Legal Defense Fund is not prepared to fold its tent on the issue. Indeed, he says he plans to redouble the organization's efforts against what he sees as a rear-guard assault on even voluntary desegregation.

Sheryll Cashin, nearly a decade younger than Shaw, is less sanguine about the legacy of Brown. A law professor at Georgetown, daughter of an Alabama civil rights activist and former law clerk to the late Justice Thurgood Marshall, Cashin would answer in the negative to virtually every permutation of the Epstein question.

Brown ended state-sanctioned Jim Crow laws, she admits, but it didn't end what she calls "our tacit agreement to separate along lines of race and class." As a result, blacks in 21st-century America remain largely separate and unequal.

"Worse, our public schools have been resegregating rapidly," she said at a recent celebration of her excellent new book, "The Failures of Integration: How Race and Class Are Undermining the American Dream." "Fifty years after Brown, the beautiful, integrationist vision that animated that Supreme Court decision could not be further from the segregated reality of the American public schools."

Duke University's Charles Clotfelter ("After Brown: The Rise and Retreat of School Desegregation") finds an interesting contradiction: White Americans may favor the idea of desegregation, but they are reluctant to embrace the actuality of racially mixed schools for their own children. Integration avoidance -- "white flight" in the North, "seg academies" in the South -- is so widespread that it no longer seems newsworthy. One result, says Clotfelter, is that the North is now more segregated than the South.

So, is America better off for Brown?

Of course it is. Just think of the disastrous educational, social and political implications if the decision had gone the other way.

Moreover, thousands of black children from middle-class (in attitude if not in income) families benefited from the opportunity to attend better-endowed schools and to compete with their white peers.

But these youngsters would mostly have done all right even in segregated schools. Desegregation was, for them, at most a marginal advantage.

The mistake was to imagine that what made a marginal difference for children of the educationally committed black middle class would make the critical difference for children already failing in segregated schools. It doesn't work that way.

Fifty years after Brown, we should have learned that there is no magic in white classmates. The magic lies at the intersection of educational opportunity and attitude -- the coming together of teachers who know how to teach and children who are ready to learn.

No one thing -- not the ballot, not changes in school governance, not desegregation -- will produce that happy confluence. We have to demand that the schools get ready for our children. But we also have to make sure, using every resource at our disposal, that our children are ready for school.

willrasp@washpost.com