JAMES CAMERON WILL go down in film history as the pivotal figure of the '80s, unless something is done about it.

He's made the cover of Time and a spot on "Entertainment Tonight," all in connection with his latest picture, Aliens, which proudly denies its existential status as a motion picture and insists on being an amusement park attraction--"America's number one roller coaster ride!" As Julie Brown said, definitely an "E" ticket.

Cameron burst into the mainstream as writer and director of The Terminator, and it is this picture that film historians and sociologists of the future will watch over and over again, their as-yet-unborn eyes slowly glazing over. It might have been another film altogether, just another cheap sci-fi flick gathering lichen on the UHF channels. But at one point in the pre-production stage Cameron approached Arnold Schwarzenegger--to play the hero.

In his own rebellious way, Schwarzenegger had begun his motion-picture career with a retrospective documentary. Those millions who saw Pumping Iron did not easily forget the images of men so surrealistically proportioned they could not reach into their own pockets. The Body, as Arnold was then known, launched himself on a quest for movie stardom, not to rest until the entire world can spell his name with only moderate effort.

Contrary to some isolated pockets of popular belief, this man is far from stupid. When presented with Cameron's script he said, in a machine gun burst of inspiration, "Vy don't I play da bad guy?"

Because of Arnold's apt suggestion, The Terminator turned out to be a memorable action picture, with a truly scary villain--a rare treat these days when real life is more frightening than the movies. If you've seen it even once, you remember at least two scenes: the one early on in which the killer robot from the Future picks up his high tech weaponry at a corner "Sport Shop" so heavily equipped it could be a member of NATO; and the sequence half-way through in which the Body lays waste to a police station, killing at least 30 people in a futile attempt to get the right one.

CAMERON HAPPENS to be a gun enthusiast. In interviews he can go on and on about calibres and muzzle velocities, incessantly rattling off brand names and model years. In his films he'll glide the camera lovingly over the polished aluminum and gleaming steel; he'll make them central characters. Rambo's trusty bow was a Cameron invention, and for Aliens, Cameron designed the "smart-guns" and "pulse-rifles" himself. That explains the sport shop scene.

As for the police station transformed into an abbatoir, not only is that scene frightening in its depiction of a totally callous and unemotional killer, it is even more disturbing in that the film does not care either. Never do we see the aftermath of Arnold's mayhem. Bodies fall out of the camera shot and out of mind as well--few screams, a little blood for color, no pain, no grief. The camera moves on to the next victim, like the gun barrel.

The public went wild.

Arnold, realizing he had hit a vein, so to speak, followed with Commando, which for a plot had a Kleenex-thin excuse to set Arnold up with an army of extras--quite literally, they played an army--and an excuse to kill them all. Note carefully: this time he was the hero.

One more time: Raw Deal, which came and went early this summer, was an oddity in that although it starred Schwarzenegger, it had a plot, characters, and a hero simple, brutal, and ethnic enough for Arnold to play without undue stretching of credibility. It almost works--the tension created as Arnold gets in dutch with some mobsters is legitimate enough, and you wonder how he's going to squeeze out of it, he being large and not easily squeezed.

And then, like a religious ritual, we see it again: the shining guns, the close-ups of the bolts slamming home like the fist of God, the spewing shells, the crumpling bodies. The film "un-asked" the question of the plot with Zen-like serenity. Arnold simply kills everyone. Everyone.

THIS IS NOT fair. A movie traditionally sets up a problem and then lets you watch the characters try to solve it. Arnold just stomps the problem into shapeless bits. Imagine that right after Rhett sees Scarlett at the party at Twelve Oaks he grabs her, drags her off, and rapes her. Brutal, horrible, you bet, but it gets you right to the credits.

Twenty years ago, when Arnold was just a boy in size 65 liederhosen, a critic coined the phrase "pornography of violence" in reaction to the Hollywood thrillers of the time. Like sexual pornography, it has grown up and grown bold since its tentative inception. Our concept of movie justice has gone from the hero pushing a mass-murderer off a cliff to the hero becoming a mass-murderer himself.

Last year, when Sylvester Stallone was visiting the Hasty Pudding Theatricals as the Man of the Year, he said that he would stop making ultra-violent films when the public stopped paying to go see them. He's right, of course. All those hundreds of gooks and Russkies and wetbacks and innocent bystanders and aliens massacred on the nation's screens are martyrs to marketing.

They will stop dying in such attractively choreographed patterns when the audiences stop cheering. But the next time you see a Schwarzenegger film, or Cameron's next opus, start counting the bodies on your fingers. When all your fingers are used up, use them to cover your eyes.