On the surface, it appears to be the former. Just as crop circles appear in a Pennsylvania cornfield owned by a reverend (Graham Hess, played by Mel Gibson) who's lost his wife and his faith in a six-month period, TV networks across the world broadcast around-the-clock footage of strange lights in the night sky. Crop circles appear across the globe overnight; the Earth's population begins to panic, fearing the inevitable end of the world. Then we're given repeated glimpses of aliens, chameleons from the black lagoon. When viewed simply as straightforward genre picture, as one more summer movie in which aliens invade, Signs is a somber, low-key kick the art-house equivalent of Independence Day, a film in which anything that makes a sound scares the hell out of you simply because everyone wanders around in dimly lighted rooms and speaks in a whisper.
And that's good enough. Signs blessedly displays a sense of giddy dark humor absent from Shyamalan's previous outings. It appears for much of the film he's merely having fun with the genre, goofing on its paranoid roots. It's the flip side of Close Encounters of the Third Kind, as bleak and menacing as Steven Spielberg's movie was mischievous and optimistic. (For extra layers of significance, Signs was co-produced by Frank Marshall and Kathleen Kennedy producers of, among other Spielberg movies, E.T. The Extra-Terrestrial.)
Signs unfolds like sneering parody. Whole scenes appear to have been lifted from Close Encounters, including one involving a meal (complete with mashed potatoes) around the dinner table. Even Graham's precocious children, asthmatic Morgan (Rory Culkin) and hydrophobic Bo (Abigail Breslin), feel like mirror images of Close Encounters' Cary Guffey, who shed a tear for his alien abductors. Morgan obsesses over a book about UFOs and the images on television; "the history of the world's future is on TV right now," he insists. Morgan, Bo and Graham's younger brother, a former minor league slugger named Merrill (Joaquin Phoenix), eventually don pointed hats made of tin foil to block the aliens from reading their minds how very Bart Simpson. (It should be noted that Shyamalan is perhaps the greatest director of children in decades; Culkin and Breslin look nothing like Gibson, yet never do we feel as though they were adopted in a casting director's office.)
Shyamalan also likes screwing with his actors' images, distorting our perceptions of them (and, perhaps, theirs of themselves). Bruce Willis, who used to strip down to his bloodied wife-beater at a moment's notice in the Die Hard spectacles, has twice played the quiet, reluctant hero in Shyamalan's films; in Unbreakable, he looked almost ashamed of his power, guilty to be so invincible. Here, Mad Max sports, and loses, the white collar of God's right-hand man, and he looks like someone who's never lost his temper. A true believer now bereft of devotion, Graham still has no idea how to get furious ("I'm insane with anger," he uncomfortably and unconvincingly shouts at an unseen intruder), no concept of how to pretend to be something he's not he's sad, mostly.
When Graham's wife was killed in a car wreck never seen but referenced a handful of times in flashback he ditched the collar and abandoned his flock. For that, he's racked with guilt, though it's a sentiment never expressed directly, only hinted at; others notice what Graham too often fails to see. Or does he? To read Signs as merely creepy, amusing sci-fi doesn't do it justice. It's far more than a celebration of or homage to the films it appears to rip off. This film, like Shyamalan's others, contains only a hint of story; the writer-director instead peddles ideas populated by characters. Shyamalan offers copious hints along the way myriad signs, if you will that beneath the familiar, funny surface is a far bigger, far more meaningful story than one in which little green men come to Earth for harvesting purposes. Shyamalan's well past his Twilight Zone phase, beyond merely playing with someone else's used toys to elicit a shock or cheap fright. He's too subtle and, yes, too brilliant a filmmaker for such trivialities; rather, he uses the familiar to make palatable far larger issues of spirituality, faith and one's need to believe in God. That he entertains without proselytizing isn't what makes him a visionary; that he makes you believe is.
Not to spoil anything because however you choose to interpret Signs, you wind up at precisely the same point but it's possible that this "invasion" is Graham's way of working out his relationship with God, his kids, his brother, his dead wife and the man who accidentally killed her. Shyamalan suggests throughout that to hate God is at least to acknowledge the existence of a higher power. In Signs, something comes from above, only it may not be little green men, just a Big Guy who doesn't need spaceships to make contact.