Not so long ago, professors of literature were known to wonder what would happen when the steep decline in church attendance produced a generation of students unfamiliar with the Bible. How would those readers make sense of the Western world’s books and poetry?

The Bible was the lumberyard from which Western writers drew their material. They could discuss Solomonic wisdom or Job-like suffering, write phrases such as “turn the other cheek” or “prodigal son,” or give their books titles such as “Pale Horse, Pale Rider” or “East of Eden” with confidence that these two-by-fours — these lengths of rebar — would bear weight in a reader’s mind.

As it turns out, that rather large question was actually much too small. Yes, the shared biblical framework crumbled, but as part of a broader collapse of all common cultural structure. History will likely conclude that the 20th century was the high-water mark of mass communication.

It made sense to speak of “the audience” for television, for movies, for music. It made sense to measure “audience share.” The television set pulled in maybe half a dozen channels. Everyone watched whatever was showing at whatever time of day the programmers chose to show it. The radio dial was the same in every automobile dashboard.

On Feb. 28, 1983, more than 60 percent of all households with a TV in the United States watched the final episode of the sitcom “M*A*S*H” — all on the same platform, the Columbia Broadcasting System (CBS), and all in the same evening. It was a fair bet that everyone you met, young and old, knew what “the Swamp” looked like and what drink was served there. They knew that Capt. B.J. Hunnicutt of Mill Valley, Calif., was named for his parents, Bea and Jay, and that Max Klinger was a fan of the Toledo Mud Hens baseball team.

Today, little remains of that common culture. Only the Super Bowl, played this Sunday in Los Angeles, attracts an audience of comparable proportions. Even the Olympic Games, unfolding on the fake snow of Beijing, cannot compel the American people to sit down and share an experience together.

The splintering of culture is not entirely a bad thing. There has never been more shows to watch, more music to hear, more essays to read. When friends or family gather, a standard feature of conversation is the sharing of recent favorites. One person has been watching “1883.” Another recommends “Will Smith’s Bucket List.” A side conversation crops up between two “Ozark” fans, while across the room someone exclaims, “What do you mean you’ve never seen ‘The Wire’?!”

The proliferation of culture means more variety for consumers and more paths for artists. YouTube and Spotify are the new star-making machinery behind the popular song.

Or, conversely, more culture can mean less variety, as entertainment platforms frantically seek out each individual’s particular tastes and offer more of the same. Did you find that World War II documentary interesting? How about eight straight hours of them? So you like Tom Petty? Here’s an entire satellite radio station devoted to him. Maybe you’d like a month of Christmas movies. Or a channel exclusively about golf.

When narrowcasting meets an especially desirable demographic slice, huge sums of money and creative talent are pressed into the service of monotonous sameness. Do you like blockbuster films about superheroes? You had better if you’re going to the cineplex.

Of course, these same forces are at work in the cultural space commonly called “news.” At the zenith of mass communication, the three major television networks produced nearly identical evening news programs. These, in turn, served as a mutual basis for political argument and competition. Today, while the network offerings remain largely unchanged, “news” is available on cable and the Internet tailored to individual tastes. There is progressive news, nationalist news, conservative news and so on. Once a person finds a congenial source, it is possible to snuggle under that blanket and shut out alternatives. The argument becomes the starting point; there is no mutual foundation.

There are signs that the splintering of culture might have limits, and that those limits might be approaching. As Paul Farhi recently observed in The Post, though audiences are scattered, there remains a hunger for common experiences. Fewer people consume the Olympics in long, narrated blocks of time on network television. But millions curate their own Olympics from selections posted to YouTube or TikTok. The fact that viewership was low for, say, the men’s figure skating competition doesn’t mean that the nation is unaware of Nathan Chen and his extraordinary athleticism.

Perhaps Americans will learn, in a similar way, to curate a new set of starting points for our political debates. In the meantime, we have a Super Bowl to watch together.