HOW MANY HUMOR theorists does it take to change a lightbulb?

"Three hundred. One to change the bulb and 299 to analyze it to death."

So pronounced Desmond McHale of Cork, Ireland, as the Third International Conference on Humor disbanded yesterday after doing battle with such sobering topics as "The Problem of Humor in the Icelandic Family Sagas," "The Early Development of Children's Appreciation of Disparagement Humor," "The Sense of Humor as a Moderator of the Relationship Between Stressors and Moods," "Humor in Contemporary American and European Architecture" and "The Effect of Mirthful Laughter on Blood Pressure."

When the conference got underway at the Shoreham Friday night, anxious onlookers wondered if the old hotel was up to the job and whether humor could endure the rigors of the convention. No one, after all, could remember when so much humor had been concentrated into so little time under a single roof. But 48 hours later, the Shoreham was observed standing on its accustomed site, and there was cautious optimism that the cause of humor might survive as well.

The conference chairman, Rufus C. Browning, an effervescent man with a nose like W.C. Fields' and a fondness for bow ties and white shoes, went further. "It's fantastic," he declared. "It's probably the most modest thing I can say about it. It has brought together hundreds and scores of people who are interested in humor. You have a cross-ventilation. You learn from each other. I'm a psychologist and I'm learning a great deal from the linguists and the sociologists."

It was, to be sure, a mixed crowd -- even without the two other conventions (Moose and American Psychological Association) simultaneously doing business at the same address. The cast of characters included such diverse types as S. Thomas Nicholls, a Presbyterian minister who delivers sermons in clown's garb and whiteface; Thomas J. Sheff, a sociologist who has been trying to test the anger-reducing value of humor "by examining facial expressions before and after laughter"; Lawrence Peter, promulgator of "The Peter Principle"; Nancy Walker (not to be confused with the actress), who is writing a book about "The 'Little Woman' in Women's Humor, 1900-1950"; Peter Bjarkman, who explains why baseball is funny and football isn't; and Ralph Nader -- the Ralph Nader -- who turned up unexpectedly at the opening-night dinner and explained his presence thusly:

"I've always been interested in humor. It's often a way of communicating that allows things to be said that couldn't be said otherwise. I wanted to see whether you can intellectualize the process and still enjoy it. If you can do that, you have the ability to deprofessionalize humor, to decentralize it and make it part of an ongoing community culture. My hope is that if we take humor more seriously, we'll be able to enjoy it more frequently."

Passers-by strained for a clue to whether this was meant seriously or humorously, but the basic question posed by Nader -- whether humor can or should be studied -- was much discussed, and there was considerable feeling that academics who theorize about humor are not, as a class, particularly funny.

"My favorite definition of an expert," said comedy writer Robert G. Orben, "is a fellow who knows 800 ways to make love but he doesn't know any girls." Humor, another conferee ventured, is like a butterfly. "If you study it too closely, you'll study it to death."

Desmond McHale, a red-haired, bright-eyed man who teaches mathematics and writes joke books on the side, took it upon himself to answer the tough question "Is Irish Humor Unique?"

"Probably not," he concluded, "but there's no other humor I know that's remotely like it." To back up his claim, he offered samples of Irish humor regarding death ("The cause of death was unknown, because he died without the aid of a doctor"), drink ("Reality is an illusion caused by a shortage of alcohol") and the British ("Northern Ireland is the tail end of the world, and the British are just passing through").

The last of these was a specimen of graffiti, McHale said. "I've done two books on graffiti. But I don't do them under my own name because the president of my college has suffered enough."

John Oldani came to the conference armed with a collection of 306 Catholic jokes. "I'm quite serious about my work," said Oldani. "I'm not so sure what some of these other people are doing."

Oldani's friend Bill Gannon, meanwhile, had been investigating the responses of Benedictine (or Trappist) monks to various forms of humor. "Even now that they've given up the vow of silence, they have trouble appreciating verbal humor," he says. The Benedictine code "forbids people to laugh," Gannon added. "It doesn't say you can't have humor. It says you should smile gently . . . because if you look at the life of Christ, he never laughed. He wept a lot, but he never laughed."

"Where does it mention baseball in Genesis?" interjected Stan Cohen, who identified himself as a bureaucrat with an interest in humor.

"I don't know," Gannon conceded.

" 'In the big inning . . .' " Cohen replied slyly.

Little restraint was shown when it came to jokes of an ethnic, scatological or otherwise potentially offensive nature. "We've come through a period where ethnic humor was regarded as in bad taste," said Lawrence Peter. "My belief is that all humor is in bad taste. Every joke will offend somebody -- maybe with the exception of wordplay."

Doubts were voiced about the quality of today's political humor, too. Arthur P. Dudden, a historian and collector of political joke-lore at Bryn Mawr College, complained that television has created a homogenized brand of humor with no point of view. Johnny Carson can make jokes about the obscurity of vice presidents (having Walter Mondale swear "to defend the Constitution and then get lost") or about personal quirks such as Gerald Ford's supposed clumsiness, said Dudden, but substance is off-limits.

Orben, a former speechwriter for Ford, recalled working both sides of the fence, in a manner of speaking, during the 1964 presidential election. While a full-time writer on "The Red Skelton Show," he was supplying material to presidential candidate Barry Goldwater and to comedian Dick Gregory. "And I always felt very guilty," he said, "because as you know, Barry Goldwater's campaign slogan was 'In your heart, you know he's right.' And I gave Dick Gregory the line, 'In your heart, you know he's white.' "

McHale was similarly gloomy about the decline of humor in Northern Ireland. In the 1940s and '50s, he said, Catholics and Protestants had a shared lore of jokes about the problems that divided them. But since the 1960s, he said, the humor has turned grisly, in keeping with the situation. The Catholic or Gaelic Irish have always had a richer sense of humor than the Protestant or Scotch Irish, he added, describing the latter as "a very dour and serious people."

In fact, said McHale, humanity can be divided into those who get the "cosmic joke" and are guaranteed to "spend all eternity in convulsions," and those who don't -- "like accountants, mothers-in-law, traffic cops and Englishmen."