Coming back from the dead is no big trick in product-hungry television. If the likes of "Treasure Hunt" and "Name That Tune" can be exhumed, it's merely fair that NBC's happily remembered "Laugh-In," a weekly series from 1968 to 1973, also return.

Unfortunately, "Laugh-In" seems to have come only half back. There's something faintly paintive and exhausted about the first of six new "Laugh-In" specials, which is airing tonight at 8 on Channel 4.

Producer George Schlatter moves the show more quickly than ever - maybe too quickly. The sketches, blackouts, one-liners and pranks fly by not so much in jolly array as in crazed desperation, as if we can be visually bamboozled into thinking we are having a wonderful time. The fact is, a great deal of the comic material is tired, feeble or childishly naughty; Schlatter seems to have preserved more of the bad things about the original show than the good.

And yet, there are priceless moments and an abiding spirit of audacity that, while lacking the punch of "NBC's Saturday Night" or the nasty merriness of a Monty Python show, still elevate "Laugh-In" above the usual level of canned prime-time comedy.

"Does TV promote violence?" a voice asks, as a man in front of a television set comes into view. Suddenly he hears the voices of Donny and Marie coming from the set. He picks up a lamp and crashes it through the screen.

Schlatter and writers thus do strike a blow or two in the name of sane decency.

Better Davis, Sen. Barry M. Goldwater, Henry Winkler, Kareem Abdul-Jabbar and Ralph Nader are among those appearing on the first show, along with a stock company of 13 over-eager and slightly stale fresh faces, not a Lily Tomlin or a Goldie Hawn among them. The original hosts, Dan Rowan and Dick Martin, are missed, because though they weren't hilarious, they provided a touchstone and a respite amid the locniness; anarchy punctuated with anarchy is enervating.

Some bits seem pointlessly oftensive. A trio of funky nuns gyrating to a rock song has the wrong tone, or maybe no tone at all. Attempts to ridicule Anita Bryant prove not only redundant but confused; it's hard to tell who's the target of lines like, "She's the missionary who can sock it to a fairy." Cops in drag singing "I Enjoy Being a Girl" make for a very cheap joke. Dousing cast members with pails of water palls after awhile.

And when all else fails, the people on "Laugh-In" just fall down on the floor. All else fails all too often. 'The Fitzpatricks'

"The Fitzpatricks" don't mess around. They hit the old dinner table and launch into saying grace even before the opening credits are over. This is to tell us we are in "Waltons" territory - wholesome, idealized mid-Americana. The one-hour weekly drama's premiere, tonight at 9 o'clock on Channel 9, in fact revolves around that small-town institution, the soap-box derby.

Though the Irish Catholic Fitzptricks live in a back-lot town (supposedly Flint, Mich.) free of traffic and litter, and although the tidiness of the environment extends to their equally tidy little psyches, they do in fact show a bit more character than the Waltons, perhaps reflecting the current TV mythology that anybody is more interesting than a WASP.

Director Gene Reynolds and writer John Scaret Young also show a sensitive knack for appreciating details of ordinary life - an egg frying in the kitchen, a paper route, rubber bands on adolescent braces, mom and dad getting cuddly in a backyard hammock as two little boys in a tree house cover their eyes in dismay. Certainly "The Fitzpatricks" presents an idyllic view of family life, but the view seems more genuinely felt and less calculated than on some similar shows.

After tonight's premiere, however, "The Fitzpatricks" will move into a Tuesday night time slot opposite "Happy Days" and "Laverne and Shirley." Grace in the credits or not, it probably doesn't have a prayer against the coarse forces of crude comedy. "Rafferty"

Viewers seem to demand their TV doctors be superheroes. That knight in white cotton, Marcus Welby, M.D., survived an incredible seven seasons, but NBC's realistic "Medical Story," which offered fallible docs and semi-happy endings, barely lasted one.

So "Rafferty," the CBS medical series premiering at 10 o'clock tonight on Channel 9, has a tough time ahead of it. One hopes an audience will discover it, because the show has a wry rough-edged, humanistic style reminiscent of such relatively realistic programs of the past as "East Side - West Side" and "The Defenders."

Patrick McGoohan returns to series TV as the definitively irascible Dr. Sid Rafferty, 23 years an Army surgeon and now a gruff blusterer just overflowing with integrity but short on comforting charm. He's the Columbo of the medical profession - "a man," says his lawyer, "who's dedicated his life to personal poverty."

On the premiere, written by James Lee and directed by Jerry Thorpe, Rafferty fends off a malpractice charge that resulted from his own good samaritanism, cures a paralyzed little girl who repeatedly complains about his lack of bedside manner, and tells off a patient whose post-nasal drip, Rafferty diagnoses, was brought about by too many kicks from cocaine.

"Rafferty" isn't entirely non-pat. There are a couple of fairly loveable sidekicks played by John Getz, as Rafferty's junior partner, and Millie Slavin as a loyal nurse. The acting stays above standard, however, with McGoohan convincingly, compellingly bull-headed, right-minder and incorigible.

He even survives such exchanges with patients as this one:

"YOu are really corny, Dr. Rafferty - the corniest," says the recovering little girl.

"You know the corniest thing in the world?" says Rafferty. "A sunrise. BUt GOd doesn't know it yet."

The contest/Maybe, but it's still a long way from those quacks Kidare, Casey and Welby, and it's much better television, besides.