One day at a time — right? It’s how we’re all existing at the moment, in covid-19 isolation, apart and yet so strangely together.

And, it occurred to me while enjoying some new episodes from the fourth season of the revived and recently rescued “One Day at a Time” (premiering Tuesday on Pop TV), that we’re all just trying to live our best sitcom lives: Confined mainly to the living room and the adjoining kitchen (sitcom sets practically invented the open floor plan), with some occasional scenes in bedrooms or hallways, venturing to other locations only when it’s essential to the plot, and keeping our conflicts and resolutions to the half-hour mark.

That’s the dream, anyhow; results within your own zany situation comedy may begin to resemble a darker and extremely dry comedy. Still, if anything in recent culture taught the American family — in whatever form it takes — about consistent closeness and good-natured togetherness, it’s the sitcom.

The format is as old as television itself (descended directly from radio and theater), so ingrained in our consciousness that we recognize it in any language: A group of people, sorted into tribal archetypes, share in an event or a minor crisis. Something new is always happening, to the extent that everything must always stay the same. The day begins, a problem stirs the household and creates chaos; people argue and snap at one another; then they share in mutual consolation and express their solidarity and love. The day ends. It’s called an episode.

The One Where Dad Learns Common Core Math.

The One Where Mom Gets Kicked Out of Costco.

The One Where Josh Forgets to Clear His Browser History.

We are talking here about the pure sitcom, and its persistence — the kind that is filmed in front of a studio audience on a soundstage, using multiple cameras, rehearsed and finessed all week until taping, when every line, every pratfall is executed with amusing and admirable precision. The audience is goosed into laughing harder than they usually might. If you’ve ever tried to imagine your own life as a sitcom, you had to supply that laugh track in your head, as all mediocre sitcoms must.

Other characters come and go. Sometimes they knock, sometimes they barge in. It’s a painful thing, to have to tell your Lennys and Squiggys, your Jacks and Karens, your Willona, your Kramer, your Schneider, to keep away and shelter in their own space, somewhere offstage.

Now that there are no sidekicks and, indeed, no audience, this episode called the One About the Pandemic is reduced to only you and the family on that old living-room set. (Or it’s reduced to just you. That’s another kind of show, with a lot of interior monologues.)

It’s easy to feel that daily life right now is not offering much in the way of what the writers would call good material. We always knew sitcoms were absurd, yet something about them remains appealingly aspirational. Is it the apartments? Is it the furniture? Is it the snappy comebacks?

Not really. Whether it’s about a family, or a group of friends who have formed the semblance of one, what endures about a successful sitcom is the togetherness, the forced chemistry.

Nobody sharpened this dynamic — and still sharpens it — better than Norman Lear, the 97-year-old producer who, with many collaborators, turned the sitcom on its head 50 years ago by giving it a realistic edge, first with “All in the Family” and later with “The Jeffersons,” “Maude,” “Good Times” and the original rendition of “One Day at a Time.” Even as a boy, Lear has recalled, he had an insatiable interest in the lives of other people, glimpsing into passing apartment windows from his seat in an elevated subway car and wondering: Who are they? What’s it like in there?

Lear’s continued presence is an essential ingredient in Gloria Calderon Kellett and Mike Royce’s highly entertaining take on “One Day at a Time,” which echoes the original, in that it is about a Cuban American nurse practitioner and Afghanistan war veteran, Penelope Alvarez (Justina Machado), who is a single mom to two outspoken teenagers, Elena and Alex (Isabella Gomez and Marcel Ruiz).

Ingeniously, the Alvarezes are tenants in a Los Angeles apartment that exactly mirrors the floor plan of the apartment in the original show — enhanced by the fact that Penelope’s pushy madre, Lydia (Rita Moreno), lives with them, occupying the alcove directly behind the living-room couch, separated by a curtain that Moreno pulls back with diva-like flair to announce her presence.

Netflix canceled “One Day at a Time” after three widely praised seasons. Fans rallied and Pop TV, which nurtured and aired the hit comedy “Schitt’s Creek,” picked it up. The show returns with a cameo appearance from another sitcom king, Ray Romano, who knocks on the door as Brian, a 2020 Census worker, greeted with suspicion in this Latinx neighborhood. In Lear-like fashion, he wants to know: Who lives here? What’s their demographic story?

“One Day at a Time” has been playing with that notion all along — the idea that families evolve, as do labels. Daughter Elena is a lesbian, with a non-binary significant other (Sheridan Pierce as Syd) whose preferred pronouns are they/them. And this version’s Schneider (Todd Grinnell) is an aging hipster who owns the building, barging in with a “Hey, fam!” and describing his role to Brian as a “cis, white-male ally — privileged, but super woke!”

Brian has to tell them that most of these identities don’t get counted in census data. He mostly wants to know how many people live here and how old they are.

“I am ageless,” Lydia purrs.

“Hispanic, Latino or Spanish origin?” Brian asks.

“I am all three,” she replies. “Do I win something?”

It’s possible that the show sometimes overreaches for relevance. At this particular moment, however, it’s both comforting and inspiring to watch as a family navigates the very real fact that they live on top of one another. In a later episode, Penelope thinks she has a night to herself in the apartment; Alex returns home for his phone and catches his mother in an extremely private and off-camera moment (she’s watching “Outlander” in her bedroom with a glass of wine and a sex toy).

The boy is obviously rattled and reluctant to talk about it. “This is not a normal conversation,” he pleads. “This family needs boundaries!”

“Boundaries?” Penelope replies. “Boundaries are for white people.”

Well, as we’re all discovering these days, boundaries are necessary for all. Our essential proximity is what gives us strength, even when warding off a pandemic. Somewhere out there, someone is having to endure the coronavirus cooped up with their very own Archie Bunker. The way to get through your own sitcom, it seems, is to embrace that which would seem trite in any other context: Forgive and forget in 21-minute cycles.

One Day at a Time (30 minutes) returns Tuesday at 9:30 p.m. on Pop TV. Also available on Pop Now and at PopTV.com.