After striking out yet again, Hal encounters famed self-help guru Anthony “Tony” Robbins in an elevator and seeks out his advice. Since this type of discussion cannot take place in a few seconds, directors the Farrelly Brothers wisely have the elevator get stuck, giving Tony Robbins plenty of time to tell Hal the secret and joy of looking for inner beauty.

At this point, the Farrelly Brothers borrow a plot line from an old Rod Serling “Twilight Zone” script. Hal suddenly starts succeeding with women who are true knockouts. The joke here is that it is only in Hal’s eyes that these women seem to be Maxim cover girls. He is hypnotized into seeing less attractive women as beauties, much to the chagrin of Mauricio, who thinks his best friend needs a new pair of contact lenses.

Hal’s life is changed when he meets a funny, vivacious Peace Corps volunteer named Rosemary (Gwyneth Paltrow). In reality -- and there is no nice way of writing this -- Rosemary is grossly obese, but as we see her through Hal’s eyes, she looks exactly like, well, Gwyneth Paltrow.

The Farrelly Brothers, who are best known for such gross-out comedies as “Dumb And Dumber,” “There’s Something About Mary,” and “Me, Myself & Irene,” are settings their sights higher by tackling the issue of beauty. It’s a concept that has intrigued humans for centuries, and the Farrellys do not offer any startling new insights. Demonstrating their inability to tackle such a subject, “Shallow Hal” crashes in its excruciating last half-hour as Hal must finally make a decision between inner and physical beauty.

To be fair, the Farrellys do address several truisms about our obsession with looks. Jason Alexander is terrific as Mauricio, who acts a one-man Greek chorus to Hal. When trying to convince a literally love-blind Hal that Rosemary is not the kind of girl Donald Trump would be seen with, an exasperated Mauricio blurts out, “Think about it, Hal. Rosemary is nice and she is funny. Attractive women are neither nice nor funny when they are talking to guys like us!”

When Mauricio begs Tony Robbins to “unbrainwash” Hal, Robbins matter-of-factly tells him that it is everyone else who is brainwashed about beauty. “It is Hollywood and magazines who tell you what is beautiful and what is not.”

And while Robbins and the Farrelly Brothers are right, they are also a bit disingenuous here: every relationship is doomed without some degree of physical spark. Another fact is that, historically, physically attractive people gravitate towards each another. The Farrellys don’t acknowledge this reality, but they do take the time to show that it is not only men who are shallow about what they want, as an attractive female character in the film makes it clear that she places a high value on a man’s bank account.

If there is a reason to see “Shallow Hal,” it is to see Jack Black perfect the title character. Black, who was terrific in a small role in John Cusack’s “High Fidelity,” has screen presence. He is currently also having success with his hilarious band Tenacious D. Gwyneth Paltrow is fine, but aside from occasionally wearing a fat suit in the film, she doesn’t really have to do much here but look desirable.

The Farrelly Brothers do throw some red meat to their longtime fans by providing obligatory toilet and flatulence jokes even as they aim a bit higher. They also still know how to utilize oldies in a soundtrack as they wisely choose such chestnuts as the Foundations’ “Baby, Now That I’ve Found You” and Edison Lighthouse’s “Love Grows Where My Rosemary Goes” for this project.