June 29, 2001 | The opening credit -- "An Amblin/Stanley Kubrick Production" -- appears startlingly contradictory, almost oxymoronic. After all, Amblin means Steven Spielberg, since it's his production company, and Spielberg means uplift and exhilaration, E.T. and Close Encounters of the Third Kind, Schindler's List (ferociously brutal, to be sure, but ultimately a triumph of the human spirit) and Saving Private Ryan (wartime horror as the backdrop for the story of a private who is, indeed, saved).

But Stanley Kubrick, the legendarily dour control freak with a profoundly despairing view of the human condition, means something quite different. Something on the order of A Clockwork Orange or Dr. Strangelove, darkly comical cautionary tales of ultra-violence and nuclear holocaust. Or 2001, which signals the dawn of civilization by showing how man-apes learn to kill more efficiently by reconfiguring animal bones as lethal weapons.

So what gives? How can this equation -- Spielberg + Kubrick -- possibly compute? The answer lies in A.I., a once-in-a-lifetime conjunction of two extraordinarily disparate cinematic sensibilities that -- maybe, just maybe -- really aren't as dissimilar as we might assume.

Inspired by Super-Toys Last All Summer Long, a 1969 short story by Brian Aldiss, Kubrick began work on the project in the 1980s, and devoted major hunks of two decades to writing, re-writing and pre-production designing. Near the turn of the century, however, the notoriously reclusive filmmaker reached out to Spielberg, a long-time friend through frequent long-distance communications, to assume control of the material. ("I think," he reportedly told his younger colleague, "this movie is closer to your sensibility than mine.") Spielberg was intrigued, but waited until after Kubrick's untimely death in 1999 to fully commit himself. Only then did he write a screenplay that claimed Kubrick's working title -- shorthand for Artificial Intelligence -- and incorporated many of Kubrick's concepts and conceits.

The end product is a boldly challenging and abundantly rewarding masterwork that should provoke more thought, spark more discussion and even prompt more passionate response, pro and con, than anything we've seen in megaplexes in much too long a time. Most of the debates will focus on the question of artistic lineage: Is it really a Spielberg movie, or a Kubrick film? I would say it's both, and more, and I would point to one scene in particular as emblematic of the intertwining.

A.I. is structured in three acts -- or, if you prefer, three movements -- that expand exponentially in scope and complexity. The first segment, set in a not-so-distant future, introduces Henry (Sam Robards) and Monica (Frances O'Connor), distraught parents whose son (Jake Thomas) has been placed in suspended animation after contracting an apparently incurable disease. Even if they wanted to have another child, they couldn't: In the wake of global warming, icecap melting and other ecological disasters, natural resources are severely limited, and childbirths are kept to an absolute minimum. But there's another way to fill the void in their lives, courtesy of Professor Hobby (William Hurt), a visionary inventor at Cybertronics Manufacturing, where Henry works.

Hobby has devised a robot boy that he claims is the first humanoid capable of both independent thought and unconditional love. The latter is somewhat disconcerting to at least one of the professor's colleagues: Even if a robot could love a human, she wonders, could a human -- should a human -- ever return that love? Good question. So good, in fact, that Hobby can't answer, so he simply brushes it aside and gives Henry an experimental robot boy to take home for a trial run.

At first, Monica is seriously creeped out by the presence of David, the ever-smiling, ever-precocious "mecha" (short for mechanical) in her home. But slowly, tentatively, she warms to the life-like creation. She takes the fateful and irreversible step of "imprinting" a parent-child bond in David's memory bank, thereby ensuring his eternal love. Haley Joel Osment of The Sixth Sense plays David, and if you had any lingering doubt that he is a genuine actor -- not just a child actor, but an actor, period -- take a look at the moment when, right before our every eyes, his vaguely synthetic smile suddenly softens into a boyish grin, and David matter-of-factly refers to his imprinter as "mommy." Amazing stuff.

But that's not the end of the marvels in this sequence. Monica, stunned by David's seemingly miraculous transformation, accepts him in a maternal embrace. Trouble is, there's something oddly, even ominously off-kilter about the Pieta-like image. The shafts of luminously bright light are a familiar Spielbergian touch. Yet, at the same time, there's something unmistakably chilly about this brightness, something reminiscent of 2001. Something ineffably Kubrickian.

More often than not, when one great filmmaker attempts to work in the style of another, the result is a hybrid that fascinates without fully satisfying, that merits little more than the respect due an ambitious experiment. Think about it: When Truffaut did Hitchcock (The Bride Wore Black), or Woody Allen did Ingmar Bergman (Interiors), what were the results? Unique achievements or merely intriguing novelties?

In the case of A.I., however, the constant tension between Spielberg's warm empathy and Kubrick's icy detachment results in a stimulating sci-fi fable that is arguably deeper and richer than anything either director might have created on his own while working from the same premise. Appropriately enough for a film that raises questions about the lines between intellect and emotion, man and machine, reflexive response and artificial intelligence, the collaboration ensures ambiguities and paradoxes, forcing us to provide our own answers.

The second and third chapters provide even greater stimulation. After her "real" son recovers and returns home, Monica is forced to choose between him and David. Inevitably, though reluctantly, she abandons the robot boy in the woods, to give him at least a long-shot chance of survival. (In the world according to A.I., robot kids are destroyed when they're returned to the manufacturer.) Fortunately, David is not alone: He's accompanied by Teddy, a walking and talking "mecha" teddybear, and befriended by Gigolo Joe (played with wit and cunning by Jude Law), a preening and prancing "love mecha" designed to service human women.

David needs all the help he can get, since he's determined to find the magical Blue Fairy described in his favorite bedtime story -- Pinocchio, of course -- so he, like the impish wooden puppet, can be transformed into a "real" boy. His journey takes him through the Flesh Fair, a garish, high-tech carnival -- equal parts demolition derby and heavy-metal rock festival -- where mechas are destroyed for cheering audiences by a flamboyantly sadistic, robot-hating impresario (Brendan Gleeson). From there, it's on to Rouge City -- think Las Vegas re-imagined by Larry Flynt -- where David obtains quick-serve knowledge by a holographic Dr. Know (who sounds suspiciously like Robin Williams). And then? Let's just say that David eventually meets his maker, but must wait a bit longer to find what he's really looking for.

There are a few scenes that last too long, and a couple of others that feel unduly truncated. (Fortunately, Spielberg fills in the narrative gaps -- something Kubrick would never bother to do -- by employing Ben Kingsley as the film's narrator.) But the only substantial flaw worth noting in A.I. is its curiously retrograde view of parent-child bonds. The whole movie revolves around a child's obsession with obtaining and sustaining the love of his mother. But, hey, what about dad? David's adoptive father moves from indifference to hostility without ever pausing even to play catch with his robot kid. And David's real father, Professor Hobby, never gets the benefit of a scene that might clarify his relationship to his creation. Meanwhile, Monica appears to be an intelligent but unemployed woman who exists only to stay at home and mind the kid(s). It's almost as though we're watching a future extrapolated from a 1950s sitcom. If this weren't such a great movie, it might be downright annoying.

A.I. is generously seeded with visual and verbal references to dozens, maybe hundreds, of other films and fairy tales. (Don't be surprised if someone, someday, devotes a doctoral thesis to images and archetypes cribbed from The Wizard of Oz.) But two allusions are especially significant. When David and Joe are deep in the woods, they are pursued by Flesh Fair "recruiters" in a vehicle that instantly recalls one of the most famous images in E.T. Credit Spielberg for having the audacity to transform one of his own magical moments into something so awesomely terrifying.

Much later, Spielberg tips his hat to the finale of 2001 with an open-ended conclusion that is either unspeakably tragic or gloriously triumphant. Or anything else you want it to be. Because, really, it isn't Spielberg's movie anymore. And it isn't Kubrick's. It's ours. For that, we should be tremendously grateful.