Phil Donahue has been doing thoughtful and entertainingly turbulent shows keyed to the upcoming presidential election even though, as he says on this morning's show, "None of the candidates have responded to our invitation to appear on the program." And this after the Donahue people managed to wrangle an Equal Time exemption out of the FCC.

Yesterday Donahue waltzed and tangoed with pugnacious pundits Mark Shields, Mike Royko and Jimmy Breslin. This morning, on "Donahue" at 9 on Channel 9, Donahue discusses political commercials with four men representing divergent and varyingly creditable views: John O'Toole, the Foote, Cone and Belding chairman who also heads the American Association of Advertising Agencies and advocates industry self-censorship of political spots; Curtis B. Gans, director of the Committee for the Study of the Electorate; archivist Julian Kanter; and Tony Schwartz, the iconoclastic media savant who, because he would not travel to Chicago, materializes on the Donahue set via satellite from New York, where he lives.

Schwartz makes by far the most sense on the program, defending political advertising as valid and attacking O'Toole, who worries about the "ethics" of it, for being moralistic on the subject of political ads but not other kinds. He holds up a full-page print ad for Marlboros that equates cigarette smoking with cowboy manliness; what's the operative ethic there? Schwartz could also have mentioned the way Madison Avenue clobbers kiddie viewers with pitches for candy and sugary cereals and promotes hypochondria and drug abuse with commercial after commercial for pain relievers and over-the-counter remedies of little or no demonstrable value.

But no, O'Toole insists that an industry panel be set up to review political spots before they air, and Gans declares that the only kinds of political commercials that should be allowed are "talking head" ads, featuring either the candidate or a spokesperson. Gans would thus like to take an already drowsy electorate and put it fast asleep.

When it is suggested to Gans that his plan would favor telegenic candidates and jeopardize uncharismatic or unattractive ones, he says, "The public I think is capable of deciding between a pretty face and somebody who has something to say." All right, but then isn't that same public able to discern a bamboozle or a con when it pops up on the airwaves? How can they be savvy one moment and naive innocents the next? Donahue shows one of those cuddly, puppy-dog Reagan spots and a woman in the audience responds to it by saying, "It's too fake. It's too make-believe." Gans and O'Toole seem to think the viewer accepts every political commercial as the truth and can be hoodwinked in a pinch. If anything, advertising has educated consumers to be skeptical of advertising.

For the umptillionth time, Schwartz's 1964 "Daisy" commercial for Lyndon B. Johnson is shown (little girl, daisy, atomic bomb), but some klutz at the Donahue show cuts off the words spoken by LBJ (". . . We must love each other, or we must die") at the end of the spot, changing the nature of the commercial and making Schwartz justifiably livid. Donahue calls it "perhaps the single-most controversial political spot in the history of the Republic" and Schwartz calls it "the purest spot that could be made in television." It's cited as an example of negative advertising, but there is nothing negative in it. The negatives (mainly that Barry Goldwater was nuclear trigger-happy) were in the eyes and minds of the beholders.

As telebeamed into Chicago, Schwartz appears as a head on the screen of a monitor that is mounted on a carpeted pedestal, so Schwartz not only sounds but looks like a mystical visitation. Donahue at one point walks up to the monitor and points an accusing finger at it. The sight brings to mind Ronald Reagan looking down on Mrs. Reagan from a huge video screen at the Republican National Convention -- or perhaps the bodyless outer-space creature carried about in a fishbowl in William Cameron Menzies' "Invaders From Mars." Schwartz simply talks the best argument. O'Toole and Gans sound like ninnies. And Donahue, earnest trouper though he be, gets to be a nuisance with his infernal "Is the caller there?" interruptions.

There is one distressing digression. Schwartz, talking about the difference between Reagan the Image and Reagan the Man, says, "I'm Jewish, and I hate to hear my president say this is a Christian country. I feel threatened. I feel uneasy." One of the women in the studio audience says she thinks it is a Christian country and that it's the duty of all Christians to convert everyone else to Christianity. Chilling, isn't it? Particularly when one realizes how openly Reagan has courted this constituency. If he would go on the Donahue show it would be worth more than a dozen heavily formatted "debates." 'Twilight Zone'

Each week for five years on CBS Rod Serling unlocked a door with the key of imagination and lured us into "The Twilight Zone." Tonight Channel 5 commemorates the 25th anniversary of the ambitious anthology program's premiere with the syndicated "Twilight Zone Silver Anniversary Show," hosted by Patrick O'Neal and airing at 8 o'clock.

The program consists of three "Twilight Zone" episodes that for some reason have been withheld from the syndicated package that Channel 20 and other stations have been playing for years. One show, "Miniature," was produced during the two seasons "Twilight Zone" was an hour long and the other two, "A Short Drink From a Certain Fountain" and "Sounds and Silences," were half-hours.

Precisely why the episodes weren't distributed previously is not stated, but one sadly begins to feel it's because they aren't very good. All three are slight, even frail, and though two were written by Serling himself, none is what could be considered a classic Zoner. The first is a classic groaner, in fact; a heavy-handed morality play in which O'Neal plays an aged man who has married a go-getter 40 years his junior. He takes a youth serum and miraculously wakes up young. But then he discovers a man can be too young, and so does the wife.

It's a labored premise, made diverting only by the rampage performance of Ruta Lee as the shrill, hedonistic wife. You couldn't, and probably shouldn't, write a female character like this anymore -- the man's brother calls her "a predatory little alley cat" -- but Lee's hellacious spitfire is a riot of overstatement.

"Miniature," written by frequent "Zone" contributor Charles Beaumont, is another story of a harassed man seeking solace. In this case it's a young and arresting Robert Duvall as a sheltered milquetoast who falls in love with the literally living doll he sees inside a Victorian dollhouse at a museum. To heighten the contrast between the real and the surreal, the dollhouse sequences of this episode have been turned from black and white into color through a new computerized enhancement process that, except for a bit of red smearing, works remarkably well. Even Mr. Serling would probably have approved. Also, it distracts one from the pokey pace of the narrative, which plays like a half-hour show padded to fill the extra time. The cast includes Pert Kelton, Barbara Barrie and William Windom.

The last episode, "Sounds and Silences," is the best, if only because it features the late character actor John McGiver in a mischievous turn as the president, owner and namesake of the Roswell G. Flemington Model Ship Company, a cantankerous landlocked sea dog who bellows his employes into neurasthenia and terrorizes his wife with a recording of the battleship Missouri bombarding Okinawa.

As so often happened in that Zone known as Twilight, the tables are turned and Roswell gets an overdose of his own noisy medicine. The payoff is disappointing, but McGiver barking "by the good lord Harry!" and overusing the phrase "in a manner of speaking" is a delight. It helps that the episode was directed by Richard Donner, who went on to do the "Nightmare at 20,000 Feet" episode and, much later, films like "The Omen" and "Superman."

Though this is not "Twilight Zone" at its best, it's still something of an event, and a better tribute to Serling than that ponderous and tortured business at this year's miserable Emmy Awards. Serling won his share of Emmys during a brilliant career, but they are tiny honors compared to the longevity that the "Twilight Zone" has enjoyed and the way it has enchanted willingly impressionable members of a succession of TV generations.