Diplomats and scholars are divided as to the impact the US Marine withdrawal from Lebanon will have on US interests elsewhere in the Middle East and around the world.
Some, such as former Secretary of State Henry A. Kissinger, argue that the Marine redeployment to ships offshore will be perceived as a defeat for the United States and therefore will have ''serious consequences'' for American credibility.
According to Dr. Kissinger, the willingness of other nations to rely on the United States will be diminished by the marines' pullback, which is coming under pressure and in stark contrast with earlier statements from President Reagan about the need to keep the marines in Lebanon.
But a number of other experts on the subject tend to disagree with this assessment, arguing instead that US credibility was already damaged by the grim spectacle of more than 1,000 marines living under fire - and underground - at the Beirut airport. As these experts see it, Arab nations will regard the deployment as a sensible move. But Arab views will obviously depend in part on what the US does next, both diplomatically and militarily.
Officials from Arab nations regarded here as moderate - most notably Egypt, Jordan, and Saudi Arabia - have for some time been telling US officials in private that the US should keep the marines in Lebanon. But the situation in Beirut deteriorated so rapidly in recent days that Us was beginning to face the choice of either pulling back or taking on Syria in a direct military confrontation.
This is something which the Arab moderates say they would not like to occur. They indicate that it would force some of them to side with their Arab brothers in Syria, although the Syrian regime is not well-liked by the moderates.
A State Department expert said that in the realm of diplomacy much will depend on how the US deals with the May 17 Israeli-Lebanese agreement, which was negotiated to a great extent by US Secretary of State George Shultz. Syria's price for reaching a political settlement over Lebanon has been abrogation of this agreement, which is regarded by the Syrians as granting unacceptable concessions to Israel. The official acknowledged that while Secretary Shultz has been loath to walk away from an agreement which was largely his achievement, the agreement is now viewed by many experts as a ''dead letter.''
On the military front, President Reagan has authorized US naval forces to provide naval gunfire and air support against any units firing into Greater Beirut from parts of Lebanon controlled by the Syrians. In his statement on Lebanon issued Tuesday, Mr. Reagan said that ''we will stand firm to deter those who seek to influence Lebanon's future by intimidation.''
But some of the experts are convinced that the threat to use naval gunfire and air strikes is more of a face-saving gesture on Reagan's part than it is a serious move to change the military balance in Lebanon.
If American planes and guns are deployed against Syrian-backed Muslim forces, this could have a negative impact on some Arab nations, experts say. West European diplomats - the British, French, and Italians - are inclined to oppose the use of such ''gunboat diplomacy,'' no matter how effective the 16-inch guns of the battleship New Jersey might prove to be.
The move to redeploy the marines and other members of the multinational force in Beirut was supported by the West European nations most directly concerned. A British diplomat said Britain would have withdrawn its small force in Beirut under any circumstances.
''Our perception is that the peacekeeping force was no longer viable, because there was no peace left to keep,'' said the British diplomat.
''There is a certain loss of prestige in pulling the marines out, and no amount of shelling by the New Jersey is going to hide it,'' said Michael C. Hudson, director of Georgetown University's Center for Contemporary Arab Studies. But he added that American prestige and credibility were suffering even greater damage by keeping the marines in Beirut.
''Many Lebanese and certainly many people elsewhere in the Arab world saw the US lining up in Lebanon with a narrowly based, incompetent, unrepresentative government,'' said Dr. Hudson.
He said that for the US now to use naval gunfire and air strikes in support of President Amin Gemayel might result in compounding the errors of a ''misguided policy.''
''Every shell that hits Muslims will be another serious blow to whatever fund of respectability we still possess in the Arab world,'' said Hudson.
''The old order is finished,'' said William B. Quandt of the Brookings Institution, who was the top Middle East expert in the Carter White House. ''But the new order does not have to be a disaster. There will be more susceptibility to Syrian influence in Lebanon and less to Israeli influence, but that could result in less violence.
''We have encouraged the extremists on both sides by our statements and our military engagement. Now we shouldn't compromise the chances for political talks by throwing our weight around at a delicate time.''
Joseph L. Sisco, a former undersecretary of state, who was Henry Kissinger's right-hand man in the Middle East, agrees that American air strikes and naval gunfire are not likely to do much to change the situation on the ground. But Dr. Sisco argues that the Reagan administration still has a chance to play a ''central'' diplomatic role if the Gemayel government can hold on to East Beirut.
In the end, said Sisco, the fundamental question for the Middle East is ''whether a reckoning can take place between Syrian and Israeli power. When you begin to broaden the process diplomatically, as far as President Hafez Assad is concerned the route to a settlement still leads through Washington.''
Many of the experts tend to agree that while the Soviet Union may be pleased with the recent developments in Lebanon, it is not in a position to control events or to exert any heavy influence on Soviet-supplied Syria.