John B. Anderson wants stature. Ronald Reagan wants to tear apart President Carter's record. And Carter wants both to beat each other up before a tiny television audience.

Tonight at 10 o'clock in Baltimore Anderson and Reagan square off in the first, and perhaps only, presidential debate of the fall campaign. If history were a guide, the first debate would be the one watched by the biggest audience and would establish impressions of the candidates that would stay with them through the election.

But this debate is like no other. It may be the first debate, but the most important player, the incumbent president, will be missing. The debate will be televised, but only by NBC and CBS. ABC has decided instead to show a provocative movie, "Midnight Express."

But "winning" the debate is no less important, and each of the three candidates has devised a strategy to do so.

Reagan's is based on the absence of Carter. It might best be called "the empty chair" approach, although the League of Women Voters, the debate sponsor, has dropped plans to place a chair on the stage.

"The principal issue is Carter's record," says Edwin Meese, Reagan's chief of staff. "The American people deserve to have it debated. We feel that Carter's refusal to debate should not change that. The reason that Carter won't debate is that he's afraid to debate his record, and we intend to make it the focal point."

Meese says that, in effect, Carter would win the debate if his record does not become the central issue in it.

If the president should reverse himself and show up at the last moment, Reagan and independent Anderson are prepared. Their staffs have taken care to brief them on this possibility, more as a precautionary move than anything else.

"We can't afford to assume Carter won't show up and try to grab the headlines," says Clifford Brown, Anderson's chief issue adviser. "I certainly would if I were in his shoes."

Anderson strategists want their man to take a different tack. They have reviewed films of the Illinois congressman's performance in the three debates he participated in as a Republican in the primaries.They concluded that he, too often, appeared to be a guy with a short fuse.

In Baltimore, they want Anderson to look solid, comfortable and well-informed -- presidential, if you will. "People respect him and know he's smart, but they have to learn to feel comfortable about him being president," one strategist said.

"We don't want him to go in there with a tomahawk," another said.

Anderson and his strategists want to be tough on Reagan's position on energy, tax policy and national defense, but not to go overboard in attacking Carter.

The president's "absence will be duly noted," Anderson said last week. "But I have no desire to stand up there and debate someone who isn't there. I hope to project more of my own views."

Anderson's theory, one strategist said, is one of transference. This adviser says two-thirds of the voters don't like Reagan. "They may or may not like Carter, but they don't know much about Anderson," he said. "If Anderson stands up to Reagan, some portion of the anti-Reagan vote will come to him, rather than to Carter, because he stood up to Reagan."

Anderson hopes the debate will increase the perception that he is a genuine contender. He is bitter that Carter has chosen to stay away. But he considers being invited to the debate a major victory in itself. "It's like apple pie or apple pie a la mode," campaign manager David Garth told one reporter. "Both are good to eat."

Reagan has based his entire campaign on making Carter and his record the central issue this fall. And that's what his advisers hope will happen tonight.

"I'd like the debate to be an examination of the Carter record and at the same time point up the difference between the three candidates as to how they would solve the problems the country faces," said staff chief Meese.

The two debaters bring entirely different backgrounds and strengths into tonight's encounter. Reagan has the skills of a professional actor, polished over a 30-year career in movies and on television. He is smooth, soothing and has a knack for crystalizing complex issues in simple, easy-to-understand sentences.

Anderson's background is that of a college debater, a lawyer and legislator. He has grappled with national issues each day for the last 20 years, and is exceedingly well-informed. However, he readily admits a "tendency on my part to preach and sermonize."

Tonight's encounter won't be a classic debate. Strictly speaking, it's more of a two-man news conference. Six journalists will pose questions on topics prescribed by the League of Women Voters. Each candidate will have 2 1/2 minutes to answer each question, then another 1 1/4 minutes for rebuttal. Three minutes has been allotted to each for a closing statement.

Reagan aides are delighted that NBC and CBS are airing the debate live. Originally, they had counted only on CBS. They now estimate an audience of from 40 million to 60 million, which would still be far smaller than the 80 million to 90 million who viewed the first 1976 debate between Carter and then-president Gerald R. Ford.

One Reagan aide, however, noted that the audience for the Republican primary debates in Iowa, New Hampshire and Illinois ran far higher than anyone had expected.

Reagan aides say the prospect of any further debates depends on what happens Sunday and on how much Carter is hurt by staying away. They strongly believe that it hurts a candidate -- any candidate, including a president -- to duck debates. They also believe Reagan handles himself well in debate situations, although Meese says, "To a certain extent Mr. Anderson will set the tone of the debate."

This goes to the heart of Carter's gamble to forgo the debate, after promising to take part. In interviews last week, Carter campign officials continued to express optimism that the decision was a correct one. "The political reaction around the country is that we're doing the right thing in not debating two Republicans," one top aide said.

From the viewpoint of the Carter campaign, one official said, there are four possible debate outcomes, three of which are favorable to Carter. The first is if Anderson goes after Reagan and damages him badly. The second is if one or both of them go overboard in their attacks on Carter and create a backlash. The third is if the debate is a dud, boring and unimpressive.

The only outcome that would hurt Carter, the official said, is if Reagan appears to be a man who is "presidential" -- one whose concerns and criticisms about Carter are substantial, not political, and who deals with the range of questions in a way that makes people feel, "this guy could do the job."

According to senior officials of the Carter campaign, the president's handlers never seriously considered joining a debate with both Reagan and Anderson if the league decided to make that the first of a series.

"From the outset," one said, "the question was, is there any reason why we should do this? No one came up with one."