If it’s obvious that Bay’s true sympathies lie with the robots, that leaves the question of whether he’s a friendly Autobot — disguised as an everyday vehicle, plastered with corporate logos and professing a puppyish loyalty to human beings and their mysterious values — or a proud but evil Decepticon, out to crush the spirit of our feeble civilization with superior technology and willpower, and replace it with something better. I think the real answer is that not even Bay knows for sure. What makes “Transformers: Dark of the Moon” interesting, to the extent that something that’s so fundamentally idiotic and soul-deadening can also be “interesting,” is what you might call its aesthetic and ontological ambivalence. To put that in English, Bay doesn’t seem quite sure what kind of movie he’s making, or what the point of it is. With “Dark of the Moon,” he pushes the dumbass summer popcorn-movie formula to the max, and then pushes beyond that into an incoherent, purely symbolic realm that’s closer to experimental cinema than to Hollywood: sunsets and helicopters and vertical plunges through space and aircraft crashing to the ground and images of apocalyptic destruction and male bodies in motion and female bodies at rest (always as observers and objects, but never as subjects), all of it set to a throbbing score that never quite reaches the moment when it tries to sell you a beer or a pickup truck or pills to make your dick bigger.

I’m not sure that Bay can save the fading 3-D phenomenon all by himself, but “Dark of the Moon” uses the format brilliantly, blending CGI elements, models and miniatures, and live action brilliantly into dynamic action scenes with tremendous depth of field and the feeling of vertiginous space. Once we stipulate that Bay’s action sequences have no respect for plot coherence or the physical laws of the universe or the fragility of the human body, we can say that they feel realistic. There’s a claustrophobic and terrifying scene involving hero Sam Witwicky (LaBeouf) and his post-Megan girlfriend Carly (Huntington-Whiteley) and a bunch of other characters trying to stay alive in a collapsing Chicago skyscraper as it’s being munched by a worm-like Decepticon named Snowcone or Showboat or something that will leave you totally wrung out — and that’s only one in an extended string of action showpieces. (Within five years of 9/11, not even Bay would’ve tried to shoot that scene.)

After the New York screening of “Dark of the Moon” on Monday night, freelance writer David Ehrlich suggested via Twitter that the film was “Luis Buñuel by way of [avant-garde cinema pioneer] Stan Brakhage,” which is brilliant but may not go far enough. While the relentless, inflated bombast of cinematographer Amir Mokri’s images and Steve Jablonsky’s score indeed suggest a self-mocking blend of surrealism and underground film, Ehren Kruger’s screenplay is more like a mashup of every possible Hollywood story ingredient. “Dark of the Moon” is a little bit “X Files” and “X-Men” and “Watchmen” and “Men in Black,” a little bit “Meet the Parents,” a little bit every one of the 873 movies where the doofy hero has an inexplicably hot girlfriend and has to keep her away from a richer and better-looking guy, and way too much of “Lord of the Rings,” with LaBeouf as Frodo and his yellow Mustang Transformer sidekick Bumblebee as Sam.

Here’s how the story goes, much of which is imparted via stentorian voice-over from Autobot leader Optimus Prime (voiced by Peter Cullen, aka “Liam Neeson said no”), or recounted via an ingenious blend of genuine 1960s newsreel footage and concocted material: Some strange spacecraft crashes on the moon in 1961 and the Russians know about it too, so John F. Kennedy says “before the end of this decade” blah blah blah, Walter Cronkite, embarrassing “comic relief” robots, Walter Cronkite blah blah blah, OMG will you check out that girl! (With Huntington-Whiteley’s ridiculous physique, ridiculous accent and ridiculous name, not to mention her ridiculous acting, Bay has perfected the platonic ideal of a teenage boy’s fantasy girl. She is an object of camp contemplation, more than lust. He is the Picasso of bimbosity.) Jokes about the bitchy unnamed girlfriend who preceded Carly, cough cough Megan Fox cough, John Malkovich doing his anal control-freak thing, Ken Jeong doing his borderline-homophobic Asian crazy guy thing, Autobots destroyed, Decepticons rule the world, wait is that Buzz Aldrin? Buzz Aldrin? The real Edwin G. “Buzz” Aldrin, second guy to walk on the Moon, is in this movie.

So is Leonard Nimoy, who supplies the voice for a long-buried Autobot leader named Sentinel Prime, who gets dug up on the Moon by Optimus and friends and brought back to Earth where some other stuff happens. He looks sort of like the king from a chess set who got covered in birthday-cake frosting, but anyway it’s all part of the evil plan hatched by Decepticon leader Megatron (Hugo Weaving). I couldn’t decide whether Nimoy’s presence pissed me off or was oddly ingratiating, but either way it’s part of Bay’s own evil plan, which is to absorb all existing pop-culture science fiction universes — Lucas, Tolkien, “The Matrix,” “Star Trek,” probably “Babylon 5″ and “Space: 1999″ — and subjugate them to his stupid robots. As for “Transformers: Dark Side of the Moon,” it’s a momentous achievement and it will make untold amounts of money and you should see it even though it’s hateful and empty and preaches the worst kind of reactionary violence without even really meaning it. Bay’s only true ideology is that of spectacle for its own sake, of anxious, self-reinforcing bigness. As Dempsey’s human villain says right before the good guys start to fight back, we all work for the Decepticons now.