Back when The Boston Globe was still headquartered on Morrissey Boulevard in Dorchester, there were signs posted around the cluttered newsroom that read: “Accuracy is the Cornerstone of Our Business.” Like a million other things that were left behind when the Globe moved to a downtown high-rise in 2017 — the four-ton marble map of New England, the fake elevator that was built for a film set, the elegant spiral staircase that led down to the library, the huge parking lots — those signs are just a memory now.

Is accuracy still the cornerstone of the news business? Or has that also been left behind?

Marty Baron, the former editor of the Globe, the Miami Herald, and, most recently, The Washington Post, was in town this month to discuss that very issue. In a lecture at Brandeis University, he announced his intention “to do something terribly unpopular in my profession these days” — namely, to defend the principle of objectivity in journalism. He described himself as belonging to a “diminishing minority” of journalists who still believe news should be reported without an ideological bias or partisan agenda, and lamented the “misguided and ultimately self-destructive direction” in which most of the media have veered.

In January, two grandees of the news industry — Leonard Downie, one of Baron’s predecessors as editor of The Washington Post, and Andrew Heyward, a former president of CBS News — issued a report titled “Beyond Objectivity,” which they compiled after interviewing scores of “news leaders, journalists, and other experts.” On the first page, Downie and Heyward, who now teach at Arizona State University, describe objectivity in journalism as “outmoded.” On the last page, they call it “a journalistic concept that has lost its relevance.” On page after page in between, they quote editors, reporters, and journalism professors who say much the same thing.

A former dean of the Columbia Journalism School, for example, dismisses objectivity as “not a very useful word” — one with a tradition that up-and-coming reporters “rightfully question.” Kathleen Carroll, who headed the Associated Press, says she stopped using the word objectivity in the 1970s because she regarded it as reflecting the view of “white, educated, fairly wealthy guys.” The editor-in-chief of The San Francisco Chronicle tells Downie and Heyward that “the consensus among younger journalists is that we got it all wrong. We are the problem. Objectivity has got to go.”

Replies Baron: Objectivity has got to stay. “Our profession will suffer horribly in public trust if it does not,” he told the Brandeis audience. “We will find ourselves contributing to political tribalism instead of helping to conquer it. As we aspire to be seen as arbiters of fact, we will be seen as activists and partisans.”

Baron’s lonely defense of journalistic objectivity is commendable. But the ill effects he warns of have already come to pass.

Fifty years ago, when Gallup first began measuring public attitudes toward the media, a large majority of respondents said they trusted journalists to report the news “fully, accurately, and fairly.” In 1976, the year Robert Redford, Dustin Hoffman, and Jason Robards starred in “All the President’s Men,” public trust in the integrity of the media reached a peak of 72 percent.

But in the decades since, more and more Americans have stopped believing that the press can be trusted. By 2015, when “Spotlight” won the Academy Award for Best Picture, confidence in the industry had fallen to just 40 percent. When Gallup tested the question last September, it was down to 34 percent — while 28 percent said they had “not very much” trust in the media, and 38 percent said they had “none at all.”

America’s news business has declined considerably since the days when Walter Cronkite, the longtime anchor of the CBS Evening News, was regarded as “the most trusted man in America.” News anchors and editors now are widely regarded as the opposite of dispassionate truth-seekers who avoid taking sides. They have a political agenda that they make little effort to disguise. In place of the old commitment to getting the facts right, the industry nowadays is committed to getting the narrative right. The result is media outlets that make little effort to hide or deny their strong leanings: CNN, The New York Times, and most of the legacy media tilt sharply to the left; Fox News tilts sharply to the right; and, as Gallup’s depressing surveys confirm, less and less of the public believes that journalists can be trusted to tell the whole truth about any story.

Of course, biased journalists don’t see themselves as biased. They see themselves as enlightened. They see themselves as having the moral clarity — and the moral obligation — to take sides on public controversies. They see themselves, though they might not say so explicitly, as combatants in a culture war in which it is important to avoid giving any credence to wrong thinking.

In his Brandeis lecture, Baron described how one veteran newsman used to reinforce the old ideal of objectivity. When Paul Taylor, a political reporter at The Washington Post for 15 years, used to begin work on a story, he would write down what he thought his reporting would show. “When he was done with his reporting,” Baron said, “he would check what he had written. If he still thought the story was exactly the same as when he set out, he knew he hadn’t done enough reporting.”

Certainly there are still journalists who work diligently to subdue their preconceptions and to retain an open mind toward sources, information, and explanations that don’t jibe with the views commonly held in their own social and professional circles. Far more typical are those who don’t. In turning away from objectivity, Baron says, the news industry is guilty of “an act of arrogance.” He pleads for a return to a journalism characterized by “more humility and less hubris.” The audience at Brandeis applauded his words. But in the nation’s newsrooms, is anyone inclined to listen?