Brit-comic Ricky Gervais stakes a serious claim to the title "the British Albert Brooks" with "The Invention of Lying," his droll, witty and thoughtful comedy about the thing that really makes the world go round.

On an Earth in which "the human race has never evolved the ability to tell a lie," Gervais plays the guy who discovers fibs, fiction, exaggerations, little white lies, whoppers to get what you want and the biggest lie of all. And that discovery may (or may not) change the world and make it a better place.

As Mark, he's a screenwriter on this alternate Earth. He's failing at the simple task of turning history (there is no fiction) into something a reader can recite to an audience on TV or in theaters. There are no actors. Pretending to be someone you're not would be a lie, wouldn't it?

Mark's a "loser," as his secretary (Tina Fey) can't help but blurt out and his fellow dapper writer (Rob Lowe) loves saying to one and all.

And that doesn't escape the notice of his beautiful but shallow blind date, Anna (Jennifer Garner, radiant). She says, "I'm not really looking forward to tonight in general." She judges him by his appearance and financial state, spilling the beans about what (some) women really want.

Mark is pretty downtrodden until that day — 20 minutes into the film — when he figures out he can tell the bank clerk he has more money coming to him than his account balance suggests. The floodgates are opened, and suddenly he can lie his way back into the screenwriting job he just lost, can fake his way to confidence, wealth and success, and even find ways to convince his loner neighbor (Jonah Hill, playing it clean for once) that he's not a lumpy loser who should kill himself.

This might have been a 10-minute sketch stretched out to movie length. But then the movie gets to the biggest lie of all, that favorite British bugaboo, religion. "The Invention of Lying" morphs into a different movie, a high-minded comedy, intellectual, even. The characters explore just what that one lie can do to help the human race, or limit it. And how would the human race react to the fellow telling that whopper about "The Man in the Sky?" They'd make him a prophet, of course. "Lying" then takes on the comically skeptical and yet uplifting tone of the 1991 Albert Brooks comedy "Defending Your Life."

But Gervais and his co-writer/director Matthew Robinson seem to confuse "truth" with "superficiality" and "tactlessness." It's not "truth" that makes people blurt out their every thought — "Your baby is so ugly!" "I don't find you attractive." Simple tact isn't "lying," it's not saying anything.