It used to be, "I think, therefore I am."

Not so with today's young adults, apparently. Thinking isn't good enough. They have to broadcast their thoughts to all corners of the universe, or at least the parts that have broadband.

"Why do we blog?" asks the navel-gazing young heroine at the beginning of quarterlife, which debuted on the Internet in November and is the first show to make the leap from cyberspace to TV. "We blog to exist."

You need to stick with me here to get the setting. She sits before a Webcam that casts her pretty face, fetchingly distorted with a bit of a fish-eye effect, onto her computer screen and out to the Internet, while another camera picks up the image for your television.

Originally, the second camera picked up the first camera's image that was going fictionally out on the Net and put it actually on the Net.

We'll get back to all these mirrors, which could be significant in the grand scheme of most people's lives, in a bit. But since you're reading about an old-fashioned TV show in an even older-fashioned newspaper, maybe you want some old-fashioned info.

Is quarterlife any good?

Yes. It can be fascinating, in the vein of thirtysomething, which none of its intended audience remembers, since it went off the air before they were 10. In addition to using no capital letters in its title, quarterlife, like thirtysomething, is a finely crafted serial about contemporary and supposedly representative people in the same decade of life.

It comes from the same creators, Marshall Herskovitz and Ed Zwick, who, with credits from The Last Samurai to My So-Called Life, have proved they know as much about getting audiences involved in the lives of ordinary film/TV/whatever characters as anybody in the entertainment business.

With three 25ish boys and three 25ish girls living in close quarters as main characters, it is a sort of anti-Friends. The kids there hooted and giggled with little visible means of support, where here, careers and the workplace take up significant time, as the inhabitants agonize over their still-squishy identities.

Dylan (Bitsie Tulloch) is the blogger, an editorial associate at a woman's magazine. "A job is where you give up your dignity in order to strip people of theirs," she says.

Scott Michael Foster (Cappie on ABC Family's Greek) plays the most interesting boy, Jed, a film artist. Savor his monologue tonight about being in love with his friend's girlfriend, sort of as if Joey loved Rachel and he were smart and introspective.

Herskowitz and Zwick settled on doing an Internet show when the original TV show pilot for ABC didn't work out. "I threw out all the characters," Herskowitz said in a conference call with reporters. "All I kept was the name."

The show, which Herskowitz called "way more expensive than anything that's ever been done on the Internet and way less than any television show has ever cost," is appearing online in 8- to 10-minute Webisodes. Six of them, cut down to a standard TV hour's worth of programming (just over 42 minutes) make each TV episode.

Online, the show has grown into "a very sizable community . . . of people who are artistic and who are creative," Herskovitz said. They tend to be creative in their critical comments, too, such as:

"Ummm, if Dylan wants to end racism maybe she wants to do it on a show where there is, um, like, maybe ONE person of color."

Only a fraction of real people hitting their quarterlife crises actually watch TV on the network schedule these days. But that's NBC's problem, says Herskovitz. His is an Internet show, not a TV show.

But it could be the start of something. His informed speculation: "Five years from now, there's going to be a continuum in America.

"And on one end of that continuum will be people who have a television with rabbit ears . . . and if they have a computer, it's dial-up.

"And on the other end of the continuum will be the people with 60-inch screens that are doing their computing and their television watching on the same instrument.

"And television and the Internet are going to have to somehow encompass that whole continuum. . . . Does the television template win out, or does the Internet template win out? Or do they just somehow combine in some weird way that we can't even imagine yet?"

Jonathan Storm:

quarterlife

Debuts tonight at 10 on NBC10