Jigsaw arrives Friday, the eighth entry in the franchise that began in 2004 with Saw, a movie whose enduring popularity was not foreseen at the time.

Rotten Tomatoes scored it 48 percent, and most critics dismissed it as a Se7en ripoff distinguished mostly by even larger helpings of lurid sadism and an even more sensational sadist — Jigsaw, the masked puppet master psycho who forces people to choose between dying a horrific death or inflicting that death on others. (Subsequent Saw movies have fared worse with critics.)

And yet here we are, 13 Halloweens (and seven movies) later, a display of endurance that suggests something in the movie has burrowed into our subconscious, the way horror movies sometimes do.

The Exorcist, for example, was a superb movie, but its biblical demon, beyond the reach of science, also played effectively on the guilt of an increasingly secular audience. Saw is a less refined piece of filmmaking, certainly, but there is also something iconic and resonant about its central, gotcha image and premise: Two random strangers awake in a dungeon and slowly come to realize that one will have to kill the other in order to survive.

One critic called it "not realistic," but, looking back, I'm not so sure.

Around the time  Saw was released, a friend called me and said, "Have you noticed how much this new millennium stinks?" He had a point. We started off with 9/11, continued with the war in Iraq, and worried about our paychecks — though the economy was being inflated by a debt binge that would collapse a few years later, and the discontent that surfaced during the last election was already at work. After decades of flat wages, folks were losing faith in the idea of America as a place of ever-increasing prosperity. Globalism was producing winners and losers instead of a rising tide that lifted all boats.

In fact, you might not get a boat. Maybe all you get is a bathtub, like Cary Elwes in Saw, waking up in a pool of fetid water, in leg irons, looking at another guy in the same predicament with hacksaws nearby. Between them is a gun, and it dawns on both of them that the way to survive is by sawing off a leg, grabbing the gun, and killing the other fellow.

I once asked Saw screenwriter Leigh Whannell if his scenario might have found a receptive audience among Americans acclimating to a grim, zero-sum, him-or-me economy. He's Australian, and had no idea what I was talking about, but he cheerfully noted — Whannell is a hilariously upbeat writer of downbeat movies — that in a world of winners and losers, he (and director James Wan) were definitely winners. "I dreamed my whole life about getting to where Saw put me. For me, it was just a very happy time in my life."

If I were to interview Whannell today, I'd run a new theory by him — that Jigsaw has grown even more creepily relevant over the years.

Let's call it Jigsawism: A malicious and manipulative intelligence engaging in creepy psychological gamesmanship, pitting one faction against another is now a grim fact of life. Put it another way: Jigsaw is real, and he's running a troll farm.

I couldn't help but think of Jigsaw when I read recent stories of a foreign troll farm magnifying rage on both sides of divisive issues, funding "wholly fabricated" social media accounts, such as Blacktivist, United Muslims of America, Secured Borders, and LGBT United. These sites showed their largely white audiences videos of a black woman firing a rifle. Or, in one case, actually hiring an MMA fighter to provide self-defense training under the banner of a fake group called Black Fist.

Attention has focused on election results, but what these trolls really want to do is divide Americans, to set us against each other, to destroy our faith in our institutions. And Jigsawism, it should be noted, has plenty of domestic advocates. When post-election stories blamed Russian intelligence services for social media campaigns designed to affect election outcomes, one angry American troll living in Utah and calling himself MicroChip angrily denounced the reports, and said that it was he, and not some Russian hacker, who built the most effective online rage forums, malgorithms, and B.S. bots on Twitter.

Did he regret spreading false information?

"I can make whatever claims I want to make," he said. "That's how this game works."

Jigsaw, who liked to frame his sadistic enterprise as a game, couldn't have said it better.

Facebook has recently promised to do a better job policing MicroChip and other trolls, foreign or domestic, but it's easy to doubt the company's sincerity. Facebook, after all, designed and conducted very Jigsaw-like experiments on users, magnifying negative News Feed content to measure the effects, and finding "the first experimental evidence for massive-scale emotional contagion via social networks."

Massive-scale emotional contagion — you may have noticed it. A protest about policing becomes a vitriolic back-and-forth about flags and anthems and patriotism. Green Berets are killed in Niger, but any discussion of U.S. deployments in Africa is supplanted by ping-ponging partisan "debate" about who conducted the most inaccurate news conference.

As somebody said: That's how the game works.

Or, as Jigsaw himself said as he walked triumphantly away from a self-annihilating cast, "Game over."