Did the critics who have fallen for Sean Penn's performance in I Am Sam see too many holiday movies? Playing a grown man with the mind of a 7-year-old, Penn doesn't do Academy Award grandstanding, exactly. He does the mincing, mushmouthed, look-what-a-dork-I-am impersonation of a ''moron'' that kids tend to perfect in second grade. As Sam, Penn waves his arms around like flippers and speaks in a voice as thick as pancake batter -- the goo-goo voice of a big, effeminate baby. Here's the irony: At a moment when political incorrectness has become the new norm, the very crudeness of Penn's caricature -- the fact that he plays Sam not as ''mentally challenged'' but as good old-fashioned retarded -- becomes his way of getting down on his knees and begging for the audience's love.
''I Am Sam,'' which wants to be ''Rain Man'' meets ''Kramer vs. Kramer,'' is a movie that leaves some people weeping, yet consider the howler at its core. Sam, an angelic bumpkin, is threatened with having his daughter taken away on the eve of her eighth birthday. The legal argument is that he won't be an appropriate parent once she's mentally older than he is. So here's a question: How did Sam, a Starbucks busboy who is too inept even to make the coffee, raise her up until then? How did he change the diapers, take her to the doctor, and pay the bills? Oh, I get it: He could do all of that because he's sweet. ''I Am Sam'' is the dumbing down of low-IQ sentimentality.