WE DO KNOW THIS," said TV Guide editorial director Merrill Panitt in a speech about TV: "The coming season will see the hottest, most ruthless, most exciting competition for ratings in recent history." There's no great evidence, however, that this dizzingly heightened network competition will result in Renaissance programming to benefit the viewer.

It just seems to mean that the networks have stocked up on pink slips and will be dispatching them more quickly than ever once the new fall season begins and the ratings take over their toll. The only justification for hope is when a network does something daring and succeeds, as ABC did with "Roots." Sure, it guarantees limitations, but it also means a television executive might be a little less eage to say no to the next daring idea.

At the moment, daring ideas have the ebst chance at ABC, partly because it is the youngest network, the hungriest (as well as currently the fattest) and because its chief programmer, Fred Silverman, seems more of a showman than a salesman, which can't necessarily be said of his CBS and NBC counterparts.

It may seem unwise to try to pick winners before the season starts, but it's also irresistible. We are abetted in this folly by advance screenings of some shows to premiere soon and by Dancer Fitzgerald Sample, Inc., a New York ad agency that each year circulates its own prognosis of the season ahead.

Nobody's perfect. last year DFS predictions included such pearls of wisdom as, "We look for 'Executive Suite' to become a series with long-term potential." It didn't make it through the year. "Serpico" was called "NBC'c most promising new show," but it went right to the dog pound.

Still, the batting average was pretty good. And nobody gets them all right, present company hardly excepted since present company wrote a year ago that "All's fair" was "the most definate hit of the new season." We were more accurate predicting "a quick crash-dive into Palookaville" for "Spencer's Pilots" and calling "Charlie's Angels" "utterly inane and a probable success."

This year's probable successes are few. These predictions have little to do with a show's quality - since many other factors come into play - byt "The Betty White Show" on CBS, a tart, bright, cheering comedy with characters and performances firmly in the "Mary Tyler Moore" tradition, deserves to be a hit and will be. "Lou Grant," also on CBS adn an MTM spinoff, won't break records but should find a substantial and loyal audiences as well.

ABC's turbulent "Soap" may get the giggest opening-night tune-in in weekly TV series history. After that, expects a drop-off as the nasty joke gets worn to a frazzle CBS's gentle "The Fitzpatricks" is essentially doomed because it is opposite ABC's one-two punch of "Happy Days" and "Laverne and Shirley," but the network is giving the series a Monday night debut Sept. 5 in an effort to get folks hooked.

"Logan's Run," a decided improvement over the tedious sci-fi movie it is based on, will do very well on Friday nights, as long as competing ABC movies aren't too grand; "Star Trek" won't start until spring, ABC's "Carter County," an insult comedy involving slapstick, Southern hillbillies and a cool northern black, could be a real sleeper, especially as part od ABC's all-ethnic Thursday night lineup.

At the end of that agenda, though, is the Redd Foxx variety show, a very questionable commodity. Viewers are not likely to embrace Foxx as himself the way they took to him as Fred Sanford because Foxx is much less interesting in a suit or tuxedo. ABC's record with the variety format is poor. Therefore, we predict NBC's new lawyer-pals, "Rosetti and Ryan," will beat him.

The CBS sitcom "On Our Own" may sail into the winner's circle as part of the CBS Sunday nigth comedy parade, sandwiched as it is between "Rhoda" and "All in the Family."

Likely to leave us quickly unless moved to other time periods: "Young Dan I Boone" (CBS), "The Oregon Trail," "Big Hawii," "Man From Atlantis" (all NBC), and the appealing but not terribly distinctive "We've Got Each Other," unless pulled along by other CBS Saturday night shows. ABC's "San Pedro Beach Bums" looked to be the "Spencer's Pilots" of 77, but the network is doing a quick overhaul for this Monday night football lead-in. Since the NBC and CBS offerings at that hour are on the namby-pamby side ("Little House on the Prairie" and "Boone"). ABC could win it just by providing a few brisk zingers.

ABC's "Love Boat," on Saturday nights, will be one of those mediocre successe that hangs around but neve really matters. NBC's "CHIPs" is an inoffensive, even likeable copbuddy show, but ut will die opposite ABC's "Knotter" and "What's Happening," at least among the younger viewers TV craves.

Networks don't just win time periods, they win nights. Based on a normal week without lots of specials, Monday, Friday and Saturday could go to CBS, with Sunday, Tuesday, Wednesday and Thrsday in ANC's pocket. But this is going to be a season in which every week is like a new year, and the opening weeks especially are heavy with "stunting," the practice of slotting lots of specials to make a big Nielsen score and get viewers in the habit of watching a particular network.

Television lends itself to rituals, however, and habits are best formed by weekly series. ABC has the most bankable total lineup as well as the clear upper-hand, with CBS a likely second place and NBC third.

The opinions expressed in the preceding paragraphs, however, are not necessarily those of anybody in his right mind.