Jimmy Carter, author of an autobiography called "Why Not The Best?", utterer of a promise never to tell a lie, proponent of removing the attorney generalship from politics, has a problem.

Carter uses the English language in a way that raises among those who hear him expectations that perhaps he did not intend and that offten he cannot satisfy. Some of the major political difficulties during Carter's campaign and in the transition period now ending were caused by this gap between rhetoric and reality.

On this inauguration day Carter will deliver what is probably his most important bit of rhetoric yet, his inaugural address. It might be well to hear or read it keeping in mind the young but already established tradition in Carter rhetoric.

Carter's autobiography is a good place to start. That title, "Why Not The Best?" is a gag-writer's dream; the political cartoonists and night-club comics have already made good use of it. Does it mean that Carter was really offering himself up as "the best?"

No - well, probably not. The title came from a brief meeting the young Carter had with Adm. H. G. Rickover, as recounted in the autobiography. Rockover asked Carter where he had stood in his class at the Naval Academy: 59th in a class of 820, Carter replied.

Then Rickover asked, "Did you do your best?" Carter began to say yes, then thought again, and answered: "No, sir, I didn't always do my best." There was a pause, and Rickover asked one more question:

"Why not?"

On the basis of that story. Carter might have called the autobiography, "Why Not the Best Effort?" or something of the sort. He chose the shorter version, with the obvious possibility of a double meaning - and he will have to live with the ensuing wisecracks for at least four more years.

The promise that "I will never lie to you" has invited the news media and other politicians to examine Carter's public statements with great care. It is a promise cutom-made for the scepticism of the post-Watergate era - a boast of sorts that Carter is better than this immediate predecessors (why not the best?) who simply won't mislead the public.

This one backfired badly. For if Carter was not caught in outright lies during the campaign, he was perceived to shift his positions, to drop certain subjects before certain audiences, to shave and shade. Carter's promise not to lie probably made it possible for Gerald Ford to make Carter's character and personality a major campaign issue during October - and that was almost enough to elect Ford.

"What you were dealing with in the campaign," one Southerner who worked for Carter observed, "was Chatauqua circuit politics . . . What that means, in essence, is personality politics rather than issue politics . . . The country wasn't ready for it, and that's why the campaign started crumbling."

In other words, Carter was trying to sell himself more than his position on issues. But he was taking positions on issues all the while, sometimes - it seemed - positions tailored to suit the audience of the moment. People close to Carter insist that this wasn't duplicitous, but just reflected the candidate's urge to win everyone's vote.

On many occasions during his long run for the White House, Carter made speeches before various interest groups in which he tried to ally himself with his audience. But an attentive reading of what he actually said reveals a man who usually chose his words with great care, adding many conditions to his broadest promises.

On health care, for example, Carter told the American Public Health Association in October that he would press for "comprehensive national health insurance." But he made a vague yet significant qualification: the program should be instituted, he said, "as revenues permit."

Also is October, Carter addressed the National Women's Agenda Conference on suburban Washington. His speech that day was a ringing endorsement of many so-called women's issues, and it contained an apparent promise to put women in important positions in his administration.

" . . . It has been argued - always by men - that qualified women do not exist," Carter said. "They do exist, and I intend to find them and put them to work."

In December, pressed as to why he was not appointing more women to his cabinet, Carter described some of the special difficulties he had encountered in trying to recruit them. But he promised to put many women at the second-and third-levels of the executive branch.

Was that a violation of his earlier promises to women? A literal reading of the record shows that it was not. Yet the earlier, carefully-worded promises had raised high hopes in the women's movement; many who held those hopes have now abondoned them.

Carter gave a classis example of his rhetoric to Walter Cronkite in a post-election interview in November. Commenting on the many postponements of deadlines in the Clean Air Act, which have allowed the car manufacturers to put off meeting strict pollution and efficiency standards, Carter said:

"I would be much more rigid in meeting the standards that are set than has been done in the past."

Did that mean he would be rigid about meeting them? Apparently not. His domestic policy adviser, Stuart Eizenstat, said last week: "It is clear that the 1978 standards cannot be met . . . At a minimum we are considering a one-year extension. Beyond that we have no commitments. We are very much in the option stage."

Of course, Carter didn't say he would be rigid. He only promised to be much more rigid than his predecessors.

Thus far, Carter has not found a comfortable way to back off campaign promises that turn out to be too hard to keep. The most troubling one recently has been his pledge to cut the defense budged by $5 billion to $7 billion.

"Without endangering the defense of our nation or our commitments to our allies, we can reduce present defense expenditures by about $5 to $7 billion annually," Carter told the Democratic Platform Committee last June.

Carter's designated Secretary of Defense, Harold Brown, has said that this one will be hard to keep, but Carter has reiterated that it is his goal. Other Carter aides have tried to reformulate the promise so that it can be met even if overall defense spending rises.

The constituency for a reduced defense budget - like the constituency for welfare reform - is vaguely defined and diffuse, but others who think they have specific promises from the new President belong to vocal interest groups - the women, for example, many of whom have already expressed disenchantment.

The merchant marine interests think Carter has promised more subsidies for them; blacks have high expectations and believe they were crucial in Carter's election; big city mayors believe Carter is on their side; the list could fill a column of print.

If Carter is forced to keep reminding these groups of the qualifications - the rhetorical fine print - in his original promises, the political costs could be high. The rhetoric that got him elected has left him with a lot of obligations.

His staff knows this; associates have compiled a book of Carter's pledges called "Promises, Promises." They decline to release it to the press.

Stuart Eizenstat, who oversaw preparation of the book, said in an interview that the promises have been ranked and categorized according to their explicitness and the context in which they were given. The result, Eizenstat hopes, is a realistic set of objectives for the Carter presidency.

At his first meeting with his Cabinet last month, Carter told his new associates:

"I've been quite cautious about what I've promised, and I would like you to honor my commitments to the American people because my word of honor is at stake."