“For a university, academic integrity is the most important thing,” Zimmer explained. “If mistakes have been made, they need to be corrected.”

Amanda Woodward, the dean of social sciences who will hand Webb the diploma, wasn’t even born when Webb arrived at Chicago to begin work on her doctorate. “This is a victory,” Woodward told me. “It’s a sad comment on the way things were in the past, but such a victory for her to come back.”

Dr. Webb, as she will shortly be, is thrilled. “The culture changed,” she said.

Gender discrimination was not, of course, only about sexual harassment or assault. The University of Chicago is granting another long-delayed Ph.D., to Cheryl Dembe, who was completing her doctorate in 1971 when her research adviser died unexpectedly. She could not find another — because she was female, the university acknowledges — and so had to drop out with a master’s.

A faculty committee reviewed Dembe’s work as a doctoral student and was impressed; it resembled contemporaneous work at Cornell University that later won a Nobel Prize. So Dembe, too, will be awarded a Ph.D.

I love these stories that end in triumph, but they should prod us to reflect. Half a century ago, we were largely blind to sexual harassment and gender discrimination, so talented women were pushed out — not just from doctoral programs but from every institution and workplace. Discrimination against gays was similarly invisible because, like sexual harassment, it was hard to talk about. Everybody lost.

So what are we still blind to today? What groups of people drop unnoticed out of Ph.D. tracks in 2019 — or out of journalism or investment banks or technology companies (or were never there to begin with)?

Race, gender and L.G.B.T. status get more attention now, but I suspect there’s little notice of the absence of undocumented immigrants, trans people and those with mental health challenges or other disabilities. The largest group of all that falls through the cracks is probably made up of those from poor, chaotic or working-class backgrounds. Children from the top 1 percent are 77 times more likely to attend an Ivy college than kids from the bottom 20 percent.