Photo courtesy of 20th Century Fox

Rosemary (Gwyneth Paltrow) and Hal (Jack Black) share a tender moment over an enormous chocolate shake in the surprisingly deep "Shallow Hal." The film opens today.

It hardly seems a likely place to find oneself thinking. It's a Farrely brothers movie.

Their films, like "There's Something About Mary" and "Dumb and Dumber," are usually funny, mostly goofy, sometimes a little scatological - but often dumb. "Shallow Hal" is all of those things, and still, thinking is unavoidable. Hmm.

The film has no illusions about being artsy or crafty. It's an out-in-the-open, screwball comedy with one of those themes you can practically read in the opening credits. The plot turns are obvious, and the characters are relatively basic. The humor is based almost exclusively on repetition of classic suburban, grade-school put-downs. And yet, somewhere in that light-hearted, clichˇd dialogue, there is a subtle, quiet revelation.

Hal (Jack Black) is shallow, and yet he barely notices, much less shows interest in, beautiful women. Before the frat factor protests too much, let that point be clarified. Hal hardly has the bragging rights of a pretty boy, and he isn't particularly smooth with the ladies, either. But that isn't his problem. As an ex-girlfriend gently points out, Hal is "kind of a dickhead."

Then Hal meets Tony Robbins (playing himself), a self-help guru who offers to cure him of his ultimately self-destructive limited perspective. Hal, convinced the cure will bring him untold legions of hotties, accepts with dog-like enthusiasm.

Enter Rosemary (Gwyneth Paltrow), a 300-pound Peace Corps volunteer whom Hal approaches while she is buying extra large panties. Hal has just seen - at least thinks he has seen - a normal-weight Paltrow gliding down the street and into the panty store. A positively glowing romance ensues.

Hal's best pal Mauricio (Jason Alexander) can't believe his eyes when he meets Rosemary for the first time. All he can say is, "Holy cow." Even Rosemary's father, who turns out to be the CEO of the company that Hal works for, tells him to cut out the act when Hal insists on going on about Rosemary's beauty.

But the two lovers are torn apart when Mauricio, after convincing Tony Robbins that Hal is in danger under the spell, dissolves Hal's heavenly vision of Rosemary by saying the magic words "shallow Hal wants a gal." Troubles ensue.

The end is happy, fret not. Of course it is. But the film is more than just happy. It's thoughtful.

One particular classic fat gag is repeated several times. As Hal and Rosemary are sitting in a public place talking, her chair gives way and she falls to the floor, splintering the collapsing furniture. But all we see is Paltrow, on the verge of tears, struggling to get up and saying, "I'm OK. I'm just embarrassed." A hush falls over the theater. "Oh," people whisper quietly to themselves.

The acting in "Shallow Hal" is genuine, and most importantly, compassionate.

Black really looks stunned when he stands facing a little girl in the pediatric burn unit of the hospital where Rosemary volunteers. She is, up until the reversal of his spell, the cutest little girl he has ever seen.

The radiant Paltrow really looks uncomfortable and self-conscious. She is soft-spoken and honest. She is kind and considerate, and she loves Hal. When her true self is revealed to the audience at the end of the film, we love her. It doesn't matter what she looks like now. We know her.