The Democratic Party arrived in New York this week as a house divided. It will leave here that way Thursday.

Its longstanding philosophical, economic and personality conflicts have not been resolved or sublimated, but, for the moment, they have been contained through compromise and political gestures.

As a result there is modest optimisim in President Carter's entourage that the party will enter the fall campaign held together by the expedient imperative of beating Ronald Reagan.

"We have two problems today," said one of the president's political agents. "The first is to get through the next 48 hours without a disaster. There are noisy [Kennedy] partisans here bent on very liberal programs. They must not be alienated or driven into open revolt. But ther is also a national television audience out there -- the electorate -- which is not spellbound by those liberal programs or by Kennedy's rhetoric. We're walking a fine line." t

The Carter-Kennedy divisions are real in terms of both personality and philosophy. The platform struggles of the last two days reflect those differences.

The Carter forces arrived here with an economic program that was to form the basis for his fall campaign. He was determined, one of his associates said, to "talk sense" to the American people over the next few months, to tell them some unpopular truths. He intented to say, according to this account, that the government cannot spend the country into prosperity, that it is no longer possible to have a virtually zero unemployment rate and zero inflation at the same time. Choices and sacrifices would have to be made.

These views were reflected in the platform offered to the convention at the beginning of the week.

"We must combine passion with self-displine," the platform said. ". . . We must forgo simplistic answers for long term solutions to our problems . . . The Democratic Party is committed . . . to combat the current recession. However, we cannot abandon our fight against inflation . . . As long as inflationary pressures remain strong, fiscal prudence is essential . . . in reducing the inflation rate."

All this was pure heresy in the Kennedy camp, an abandonment of all the Democratic Party had stood for over the years. What is needed immediately, the Kennedy people said, are massive new government spending programs to overcome the recession and put people back to work. The fight against inflation, they said, could not take priority over immediate economic relief.

Kennedy expounded this message with a vengeance Tuesday night in an emotional speech that electrified his audience:

"Let us pledge that we will never misuse unemployment, high interest rates and human misery as false weapons against inflation.

"Let us pledge that employment will be the first priority of our economic policy.

"Let us pledge that there will be security for all who are now at work. And let us pledge that there will be jobs for all who are out of work.

"These are not simplistic pledges. Simply put, they are at the heart of our tradition; they have been the soul of our party across the generations . . . We dare not forsake that tradition."

Moments later, minority planks embracing these concepts were adopted by the convention. Carter's call for restraint and sacrifice were repudiated, most specifically in the Kennedy plank calling for a $12 billion program to create 820,000 new jobs immediately.

This defeat had been anticipated by some of Carter's people, and before the evening began they had made conciliatory gestures to Kennedy. They issued his followers hundreds of extra convention passes to allow them to hear the speech and take part in the voice votes that followed. And they made no effort to limit the time he would be given to speak.

Today, still faced with a delicate political problem, they drafted a conciliatory response by Carter in which he expressed his reservations but emphasized that his purposes and Kennedy's were the same.

"Our platform," Carter said, "has set forth great goals and principles for the next four years. I enthusiastically endorse these ideals which were so eloquently put forth by Sen. Kennedy last evening. Fritz Mondale and I will strive to achieve them. A strength of our party is its diversity. aWhile we may disagree and sometimes vigorously debate -- on matters of timing, approach, and particular programs -- we share a common commitment to improve the lives of average Americans . . . I will proudly run on the platform of the Democratic Party."

The Kennedy forces created other problems for the president. They adopted a plank endorsing federal funding of abortions despite Carter's known opposition. And they attempted unsuccessfully to force through a plank calling for abandonment of the MX missile program. There were many conflicts of this kind which, however they came out, emphasized divisions within the party that existed before the convention and will exist when it is finished.

The question for Carter, then, is how to defy Lincoln's dictum that a house divided cannot stand.

The first necessity, some of his associates believed, was to get through the convention without an open break with Kennedy and his followers. The nightmare was a scene in which the president is met by thundering boos as hundreds of Kennedy people storm out of the hall, all on national television.

The second necessity, the Carterites believe, is to pacify Kennedy without appearing to the electorate as leftist, big spenders. Carter's response to the platform and his acceptance speech Thursday night are calculated to achieve that end.

The third objective is to keep the Kennedy forces in the party through the November election. That may depend, Peter Edelman of the Kennedy staff said, not on what Carter says in New York today and Thursday but on what he says in the weeks and months ahead.

The Kennedy following is a house of various mansions. One of the more leftwing occupants, Rep. Ronald V. Dellums of California, finds the revised platform more than acceptable. It demonstrates, he said, that the "liberal and progressive forces" are in control of the Democratic Party.

The Carter hope, clearly, is that Ronald Reagan will unify the Democrats.

"What disturbs me now," said Maynard Jackson, the black mayor of Atlanta, "is the depths of the wounds in the Kennedy camp. What is truly needed is for Kennedy to give a tough, ripsnorting endorsement of Jimmy Carter."

The Carter hope, clearly, is that something of the sort will happen simply out of common fears of a Reagan presidency.

There is yet another view of all this. Edwin Meese, a major figure in Reagan's camp, dismisses the whole Democratic platform storm as much ado about nothing.

"There is really nothing novel in the platform," he said. "It is a recitation of traditional Democratic programs that haven't worked."

An official of the Democratic platform committee shares that view in part:

"The delegates are having fun. Let them have their votes.By noon Friday nobody will remember what's in it."