Last night's debate among the six declared candidates for the Republican presidential nomination would be hard to satirize. At times it out Doonesbury'd "Doonesbury" and was loonier than "Washingtoon." We might consider it a combination "Wednesday Night Live" and "Not Necessarily the Next President."

As he did for seven Democratic hopefuls in July, William F. Buckley played host to the Republicans in a special edition of his "Firing Line" show that originated in Houston and aired on public television. The two clear winners in the debate were already considered the two foremost contenders: Vice President George Bush and Senate Minority Leader Robert Dole of Kansas.

Bush seemed straightforward and, at least as compared with his competitors, humane, although he still gives the appearance of a man in a perpetual state of annoyance. Dole, apparently advised to tone down his image as a wit, brightened as the two-hour show rolled on, and brandished his knack for plain speaking. He said of the current president's arms control efforts, "I don't think Ronald Reagan is going to make a dumb deal."

By contrast, the other four candidates were studies in self-caricature. Alexander Haig was determined to confirm whatever worst fears anyone might have about him, the hawkish military man who brought to mind the unstable Gen. Jack Ripper played by George C. Scott in "Dr. Strangelove."

Old "I'm-in-charge-here" Haig said the president must mainly be "a tough leader," characterized Mikhail Gorbachev as "the most cunning, most sophisticated Soviet leader since Lenin" and called on congressional leaders to "reinstitute discipline" within their ranks. What did he mean -- paddling after class? Haig also declared the United States to be afflicted with a "mindless deficit."

For a viewer, the question soon came down to be a matter of which candidate was the scariest. Haig appeared to take honors there, but Delaware Gov. Pete du Pont kept challenging him. You've got to hand it to a fabulously wealthy man who bases his candidacy on such anachronistic issues as cracking down on welfare cheaters and who keeps threatening to overhaul Social Security.

Du Pont did inject some much-needed friction when he persisted in attacking Bush, at one point drawing loud boos from the crowd for saying Bush had been a follower, not a leader, and one who had not set forth "any vision, any principles, any policy" in his campaigning.

Bush, knowing du Pont prefers the nickname "Pete," turned skillfully to his attacker and said, "Pierre, let me help you on this," then labeled as "a nutty idea" and "a dumb one" du Pont's Social Security scheme.

Du Pont easily copped for himself the Lyndon LaRouche award for political kookery. For the record, though, he did get the loudest and most sustained applause from the right-wing audience when he claimed Supreme Court nominee Robert Bork had been "savaged by the Senate Judiciary Committee."

Pat Robertson, the TV evangelist, offered the most slickly prepared autobiography during a segment of short films in the first half-hour of the telecast. Robertson began in long shot and then walked boldly toward the camera, eventually discovering his wife in the foreground.

This was a lot better than Haig's. He was seated so rigidly and formally next to the missus that when he described her as "my wife Pat, who's been at my side for the past 37 years," he begged to be taken literally.

Robertson, as it happens, didn't get around to dropping God's name until his closing statement on the program, when he said we should be a "God-fearing" people and "one nation under God." But looking into those squinty little eyes of his, and confronting that Jim-Bakkerish, borderline demonic smile, the thought occurred that maybe we should be a Pat-fearing nation. Just in the interest of self-preservation.

Jack Kemp, the lullaby candidate, bravely came out in favor of capitalism, free enterprise and our "inalienable rights." You can say this for Kemp; he is not frightening. Not unless one has an unreasoning fear of wax figures or Teddy Ruxpin dolls.

Kemp, like all the others, rattled his saber at the Soviets. He said nuclear deterrence worked at the end of World War II, so it should work now. Well, nothing much about the world has changed since 1945, now, has it?

When Kemp talks, he sounds like a man on helium.

Du Pont was not alone in lambasting Bush; Haig and some of the others joined in. At one point, discussing arms treaties with the Soviets, Haig growled at Bush, "I never heard a wimp out of you." Perhaps he meant "whimper." Perhaps it's just that people associate the word "wimp" with Bush, but he didn't seem very wimpy in Houston.

Most of the friction was kept lighthearted. During a segment in which the candidates were encouraged to badmouth one another, du Pont was supposed to address his remarks to Kemp. Dole interrupted him: "You're looking at me. Kemp's over there," he told du Pont, and du Pont replied, "Yeah, but the camera's behind you." He was trying to look into the lens. Of all the contenders, du Pont seemed the most heavily coached in telegenics. Bush seemed the least coached, and that may be why he was also the most effective.

There were the usual flatulent platitudes. Dole is not immune to using them. He repeated the phrase "strong leadership" twice in his bio and again in his closing statement. When Buckley asked a question about an antiabortion amendment, Dole started answering directly ("I do not agree with Roe v. Wade") then somehow wandered off into saying there ought to be more Republicans in the world (fewer abortions would help solve this?) and then non sequitured, "What America wants is leadership."

Du Pont managed to segue from abortion to one of his favorite themes, "drugs in our classrooms." That's right, not just in our schools, but in our classrooms. Perhaps in our lockers, our cafeterias, our language labs and our bicycle racks as well.

The tattered old political trick of answering a touchy question with the answer to an altogether different question doesn't work very well in such relatively intimate surroundings as the "Firing Line" show. This kind of hortatory evasiveness is more noticeable in conversational, as opposed to rhetorical, situations.

Thus the two Buckley sessions reemphasize that whoever sponsors the major presidential debates next year should keep them as informal and open to spontaneity as possible. It helps prevent candidates from falling back on packaged cant.

Buckley, who cochaired with former Democratic Party chairman Robert Strauss, was his usual insufferable self, clinging to his clipboard and the ostensibly witty remarks thereon and clearing his throat so noisily and intrusively throughout that he sounded like an entire Sunday morning congregation rolled into one. If the program were more professionally put together, someone might have the sense to turn down Buckley's microphone when others are talking so that his rumblings will be less noticeable.

The first hour of the debate was essentially a prolonged lull. Dole noted, once sparks started to fly, "I thought this thing was dying on the vine." It didn't die on the vine exactly, but it didn't really burst into bloom either. One may have felt it unnatural for so many dull white men to get together without a deck of cards.

If only Jeane Kirkpatrick had declared and been part of the gang; that would have livened, and brightened, things up somewhat. During an unusually introspective moment, Dole said of the Republican Party, "We're perceived as not caring about people." Little said or done on the "Firing Line" special did anything to counter that perception. But one thing we do know: They all care about winning.