In 3rd Rock, nobody is normal and there is no true norm, which is much truer to the world in which we live. Unlike a show like the Beverly Hillbillies where we principally laugh at the Clampets, we're laughing it the Solomon's AND the people around them. It takes the perpetually utilized premise of placing a group of outsiders in the middle of a "normal" group of people and completely turns it around. My feeling is that the main source of 3rd Rock's brilliance is it's mocking classic sitcom formula. Then there's Nina, the secretary Don, the cop of Sally's dreams the lovable nympho landlord, Miss Dubcek and countless other students, colleagues, peers and various characters that teach the Solomons, themselves and us about society (I love Judith.) The show is as observant as any I've ever seen and equally funny with it's slapstick, zany dialogue, unusually usual situations and running gags.
Jane Curtin as Mary, Dick's love interest, tries to appear normal and show the Solomon's that they aren't but is really as bizarre as anyone else on the show. The satire is complete with the addition of the stereotypes they encounter every day. The four play together as a remarkable comedy team, each with their own quirks that evoke criticism on society. The show hasn't used him as an idle, but as another resource for more of the social observations with which the show is bursting at the seems. Finally, teenager Joseph Gordon-Levitt as Tommy is most impressive in the fact that he plays at the same level of the rest of the ensemble.
He acts as what at first might seem like the dumb member of the alien four, but in fact, his idiocy is what exposes that of the people that surround him in how they deal with him. French Stewart as Harry is more or less the cute little pet and adds tremendously to the show. I can't wait to see her in other comedic roles, my main fear being she'll fall into toilet humor instead of something sophisticated.
Her physical presence is so amusing she can crack you up just by standing there. She adds some amazing physical comedy to the show's ensemble.
If you like this show, I strongly suggest you see some of his movie work such as The World According To Garp, the movie I hate to love and love to hate, but Lithgow's performance falls on the love side of the scale. John Lithgow is simply one of our best in one of his best roles as Dick. But 3rd rock is rollicking comedy and nothing but. It's a Ross and Rachel world out there, and the brilliance of 3rd Rock was often overshadowed by soap operas disguised as sitcoms. Sure it won its share of Emmies, but that doesn't mean anybody watched it. While I've been a faithful viewer going on five years or so, the show never got the appreciation it deserved. It's a low down dirty shame about 3rd Rock.