Here we go again. Another New Hampshire presidential primary campaign is beginning and, even in its opening moments, it is a blend of the sensible and the surrealistic like nothing else in American politics.

It is Sen. Ernest F. Hollings arguing doggedly the unpopular position that restoring the draft would best enable America to defend its interests without resort to nuclear war. It is the same Hollings impishly telling the audience at St. Anselm's College that, "If I become commander in chief, I'll get rid of all the helicopters (in the armed forces) and make them march in and hold the ground like we used to do, instead of flying in and flying right back out to pick up a beer."

It is Sen. Gary Hart pulling up a chair at a Keene restaurant and talking quietly for 10 minutes with Elissa English and Erika Radich about his military reform ideas, as if their two votes were more important than any of the thousands of others that will be cast here on Feb. 28. It is the same Hart cheerfully throwing a snowball at the Newsweek magazine cover photo of rival Walter F. Mondale--to the delight of the photographers.

Since 1952, when New Hampshire established its claim to be a president-maker by giving Dwight D. Eisenhower his first boost to the White House, the contest in the snows has become a thriving industry. John Kennedy in 1960, Richard Nixon in 1968, Jimmy Carter in 1976 and Ronald Reagan in 1980, and all their unsuccessful challengers, added to its stature.

Now its allure is so great that it draws not just legitimate candidates and semi-legitimate journalists, but a lot of others whose credentials are more than slightly suspect.

You may think, for example, that President Reagan has no opposition for renomination. That may be true in 49 other states and the District of Columbia. But four rivals had filed here when the listings closed on Jan. 3. One is Harold Stassen, who was a serious candidate for president in 1948 and has been running ever since. Another is California businessman Benjamin Fernandez, who won a bit of fame in 1980 as the first Hispanic presidential contender, and obviously liked the experience.

The third is Gary Richard Arnold. Arnold was a Republican congressional candidate from California in 1982 and gained 30 seconds of celebrity by standing up at a White House candidates' briefing and criticizing administration policy to Reagan's face. The President was provoked enough to tell Arnold to "shut up." Instead, he has come to New Hampshire.

Finally, there is one David Kelley of Pigeon Forge, Tenn., the self-styled "last Confederate soldier." When he filed, he told wire-service reporters that he favored unilateral nuclear disarmament, a balanced budget amendment, abolition of the federal income tax and the exile of blacks to Africa--but "not on a compulsory basis."

The Democrats lack such vivid qualities, but they more than make up for it in quantity. In addition to the eight nationally recognized (more or less) candidates, 17 others have filed for president on the Democratic ticket.

Political science professor William Kreml of the University of South Carolina is running in order to publicize his belief that the Constitution should be rewritten to incorporate certain elements of the parliamentary system. Chemistry professor Cyril Sagan of Slippery Rock (Pa.) State College wants to gain attention for his ideas on strengthening family life.

Billings businessman Martin J. Beckman, who bills himself as "Montana's fighting redhead," wants to denounce the iniquities of the Internal Revenue Service. Florida lawyer Richard Kay will use the primary to oppose the extension of civil rights protection to homosexuals.

Florida is heavily represented--perhaps overrepresented. In addition to ex-governor Reubin Askew, who has been running for president for over a year, ex-governor Claude Kirk Jr. jumped into the primary. Kirk, who used to be a Republican, is perhaps hoping to gain revenge for the defeat Askew inflicted many years ago.

This is a strange mix--part circus, part serious. The press and television pay attention, because New Hampshire has established a track record as a maker and breaker of presidents. The publicity-seekers come because they know they will find reporters and cameras waiting.

The best of the New Hampshire process is the opportunity for quiet interchanges, when citizens and would-be presidents take each other's measure in extended dialogues. The worst is the clatter of the overgrown publicity machine that makes it all but impossible for the thinking and sorting out to take place, and then magnifies the impact of New Hampshire's results to the point of absurdity.

It doesn't make a lot of sense. But, as David Wysocki and Mel Bolden say in their "New Hampshire Presidential Primary Rule Book," a spoof on the institution, "Anyone who survives the New Hampshire primary deserves to be President."