Time is an abstract and collectively imaginary concept, and often our brains must latch onto contemporary metaphors to fathom its churn. So I will say, with all due respect to our (gulp?) probable future president Matthew McConaughey, this was the year I no longer felt that time was a flat circle.

I found it to be moving more like a social media feed, dominated by freshly excavated and somewhat randomly retweeted remembrances of the recent past. A bit of cultural flotsam from the last 25 years would suddenly drift back up to the top of our collective consciousness and spread wildly, demanding renewed attention in the context of the present.

Sometimes this was harmless fun — a welcome distraction from the fact that, this being Year 2 of a global pandemic, the actual present was depressing and exhausting to think about for too long. So everybody started watching “Seinfeld” and “The Sopranos” again. Taylor Swift released note-for-note replications of two old albums, allowing everybody a brief opportunity to get mad at an ex-boyfriend she had stopped dating a solid decade ago. “Bennifer,” the most gloriously of-their-time celebrity couple of the early aughts, were back together, baby! It was almost enough to make you want to live-tweet a contemporary rewatch of “Gigli” and declare it an unfairly maligned and subversive take on sexual fluidity, or something. (I said “almost.”) In 2021, the turn-of-the-millennium past was back in a big way, even if the eyes and ears through which we were taking it all in had grown older and — just maybe — wiser.

A word I sometimes noticed bandied about this year when talking about pop culture was “presentism.” Like so many other terms whose meaning has been distorted and hollowed out by contemporary, social-media-driven use — “problematic,” “intersectionality,” “critical race theory” — it began its life as jargon confined mostly to college classrooms and undergraduate term papers. As the Oxford English Dictionary defines it, “presentism” is a philosophical term describing “the tendency to interpret past events in terms of modern values and concepts.” To translate that into pop-culture speak, it is the modern tendency to look at an old video of David Letterman grilling Lindsay Lohan on late-night TV and feeling compelled to tweet, “Yas queen, drag his ass!”

But this year some of these reassessments went refreshingly deeper, and they were long past due. What’s the opposite of partying like it’s 1999? Recycling the empties, dumping out the ashtrays and soberly assessing the damage to property or — worse — people? Whatever it was, there was suddenly, and very belatedly, a lot of it going on in 2021.

All year, headlines and trending topics were monopolized by old, familiar names suddenly being scrutinized under new lights, using language and means of critical thinking that had gone mainstream in the wake of both the #MeToo reckoning and last summer’s protests for racial justice. The lines separating heroes and villains, victims and monsters, were being redrawn in real time. Flashbacks to salacious media coverage of the late ’90s and early 2000s were reminding people how horribly both Britney Spears and Janet Jackson had been treated in the court of popular opinion, and how Justin Timberlake’s white male privilege had allowed him to skate through both of these controversies unscathed. (The New York Times released documentaries about both Spears and Jackson.) In a New York courtroom, the victims of R. Kelly were telling the same stories they’d been telling for years and finally being heard, if damnably too late to reverse the trauma he had inflicted in plain sight, while far too many of us turned away.

So many of these conversations were so long overdue, kicked down the road because of how difficult it is for masses of people to face hard truths. But documentaries like “Framing Britney Spears,” “Allen V. Farrow” and “Surviving R. Kelly” (from 2019) helped bring fresh attention and outrage to old injustices in part because they took the popular form of the streaming true-crime series, using a familiar narrative vocabulary to sharpen viewers’ understanding of familiar events they thought they knew all about. As uncomfortable as most of these documentaries were to watch, their mass consumption helped shift public opinion, set the terms of cultural conversation, and in some cases maybe even expedited justice.

But not every reconsideration felt as vital as the next. By now it feels like there is also a thriving and somewhat formulaic cottage industry for content that reconsiders the recent past through a contemporary critical lens. In September, Rolling Stone released an updated version of its “500 Greatest Songs of All Time” list, a fascinating and (given the racial and gender biases of its previous iterations) even noble endeavor whose critical perspectives will nonetheless, in time, look as dated and of-their-moment as those of the one it replaced. A month later, the online music magazine Pitchfork caused a brief furor when it “rescored” 19 of its old reviews, seemingly to reflect changing public opinions. (I worked there from 2011 to 2014, and one of the rescored reviews was mine.)

Operating from a similar point of view, HBO has released several music documentaries in partnership with the entertainment and sports website The Ringer that invite the viewer to relive massively popular ’90s cultural phenomena (the rise of Alanis Morissette; Woodstock ’99) through the seemingly more enlightened perspective of 2021. (I worked at The Ringer from 2016-19.) Directed by the filmmaker Garret Price, “Woodstock 99: Peace, Love, and Rage” first came to HBO Max in July. The documentary makes the case — through repeated and rather heavy-handed montages of Columbine, the Clintons and music videos featuring angry young men in cargo shorts — that 1999 was a very particular time in pop culture, seemingly alien to anyone who didn’t live through it. The economy was prosperous and so bands were apolitical, raging against nothing in particular, or so we were told.

“The intention was to do something contemporary,” the Woodstock promoter Michael Lang says at the end of the film, summing up the hubris of the original festival’s turn-of-the-millennium update. Woodstock ’99’s catastrophic failures — countless sexual assaults; several preventable deaths; massive, horrifying crowds of white people gleefully rapping the N-word — are presented in the documentary with a comforting assurance that this was the kind of thing that only could have happened in the wacky, angsty late ’90s. Never again! Right?

It is surreal to watch this documentary in the aftermath of November’s Astroworld Festival tragedy, which led to 10 deaths. The parallels to Woodstock ’99 (or, since time is still kind of a flat circle, the 1969 Altamont Free Concert) are haunting, with security forces that were inadequate to control such large crowds. The past, it seemed, wasn’t even past.

At one point in “Woodstock 99,” the music critic Steven Hyden reflects back on the aura surrounding the original 1969 festival, and how much of it was constructed by the idyllic documentary “Woodstock.” “The problem is that instead of learning from mistakes that were made, we instead created this romanticized mythology in the form of the documentary,” Hyden said. “People watched the film, and they chose to believe that’s the way it really was.”

I wonder if something like the opposite is happening now: The allure of presentism is causing people to romanticize contemporary perspectives at the expense of an excessively vilified past. It’s uncomfortable to dwell in gray areas, to admit imperfections, to acknowledge blind spots — better to have a 100-minute documentary or four-part podcast to allow us to tidily “reconsider” something that we got wrong the first time around, so we never have to think too hard about it again.

But to believe the linear, one-dimensional narrative that Woodstock ’99 or misogynistic media coverage of Britney Spears can only be visible in hindsight is to gloss over the fact that plenty of people felt uncomfortable with these phenomena while they were happening. To dutifully perform belated horror at how tabloids wrote about Spears in the early 2000s, how macho rock culture was in the late ’90s, how blithely racist white people who listen to hip-hop used to be, is in some ways to believe a comforting fiction that all of these problems have been solved once and for all.

The past was imperfect, yes, but so is the present. Inevitably, the future will be too. The lesson to be taken from all these reconsiderations is not necessarily how much wiser we are now, but how difficult it is to see the biases of the present moment. If anything, these looks back should be reminders to stay vigilant against presentism, conventional wisdom and the numbing orthodoxy of groupthink. They invite us to wonder about the blind spots of our current cultural moment, and to watch out for the sorts of behaviors and assumptions that will, in 20 years’ time, look nearsighted enough to appear in a kitschy montage about the way things were.

The best movie I saw this year broke this cycle, essentially by presenting another, more harmonious way the past and present coexist. Todd Haynes’s remarkable and immersive documentary “The Velvet Underground” didn’t so much depict the past through the limited critical lens of the present, but instead conjured its own visceral temporality — a little bit like Andy Warhol did in his own slow, strange art films.

I was not alive in 1967, the year the Velvet Underground released its debut album, but for a heady and hypnotic two hours, I could have sworn I was. Split-screen images suggested the validity of multiple truths. The music’s blaring brilliance rained down self-evidently rather than having to be overexplained by talking heads. Lou Reed, John Cale, Nico and Moe Tucker all seemed, at various moments, to be both geniuses and jerks. Neither glorified nor condemned, 1967 came flickering alive and seemed about as wonderful and awful a time to be alive as 1999 or 2021. Or, it stands to reason, 2022.