The billion-dollar standoff between the Trump administration and Harvard features stark disagreements — and at least one two-word point of convergence: “viewpoint diversity.”

In its letter last month threatening to cut Harvard’s federal funding, the administration accused the university of lacking it, and demanded that Harvard submit to a thorough external audit of the problem.

“Each department, field or teaching unit must be individually viewpoint diverse,” the letter said. So too must be the student body, staff and leadership. A failing grade, the letter warned, would result in corrective measures, including the deliberate recruiting of “a critical mass” of new faculty and students to correct the imbalance.

Harvard has rejected the Trump administration’s demands, calling them a threat to academic freedom and the political independence of higher education. But in a letter to Harvard affiliates informing them that the university was suing the government, Harvard’s president, Alan Garber, echoed that vocabulary.

“We acknowledge that we have unfinished business,” Dr. Garber wrote. “We need to ensure that the university lives up to its steps to reaffirm a culture of free inquiry, viewpoint diversity and academic exploration.”

The term viewpoint diversity, which also appears multiple times in Harvard’s recent report on antisemitism, may be unfamiliar to many. But it has been circulating in higher education for the past decade, prompting debates of its own.