Although the Reagan administration has branded Libya's Col. Muammar Qaddafi public enemy No. 1, there is no agreement on what a number of government specialists think might be the best way for this country to dramatize its commitment to combat Qaddafi's military adventurism and political subversion in Africa.

That device is economic sanctions, and above all a halt to U.S. purchases of Libyan oil.

Some government officials studying the situation would like to cut off American purchases of Libyan oil as "the right thing to do" regardless of effectiveness. But a major complicating factor is that President Reagan and White House counselor Edwin Meese III have both rejected such a move in public precisely because, in their view, it would not be effective or in U.S. interests.

The essential contradiction in American policy toward Libya thus remains: while fingering Qaddafi as a major threat, and even after shooting down two Libyan planes last summer, the United States continues to spend billions of dollars to buy Qaddafi's oil. Although current U.S. imports are down substantially from last year, officials emphasize that this is due to price, other economic factors and the general oil glut, rather than to any political decisions here.

The oil revenues not only help finance the kinds of Libyan activities this administration regards as dangerous, but some of the money also undoubtedly finds its way to the Soviet Union, which needs dollars to finance purchases from the West, because Qaddafi buys lots of Soviet weapons with U.S. currency.

Last month, the chairman of the Senate Foreign Relations Committee, Charles H. Percy (R-Ill.), called on the president to conduct a review "of concrete steps the United States could take, individually and in concert with its allies, to bring economic and political pressure on Libya."

Actually, such a review, centered in the State Department, had already begun and is expected to be completed within "a matter of weeks," officials say.

Sources say the options under study range from a U.S. boycott of Libyan oil to more rhetoric. In between, sources say, are such things as a ban on export of spare parts for American-owned oil facilities in Libya, a declaration that U.S. passports are not valid for travel to Libya and a more concerted effort to force the withdrawal of some 2,000 Americans still working for U.S. energy firms and living in Libya. These workers are the key to effective operation of the oil facilities in Libya.

Officials say there are drawbacks to all of these and other possibilities and that the fact that there is a review doesn't mean there will be a decision to act. "I would have to say that as of this moment, we have not found the formula for an effective economic program," the director of State's office of North African affairs, Robert Flaten, told a congressional committee last week.

Interviews with officials involved with the review suggest that three main points of view predominate.

One is the view espoused by Reagan and Meese, which is that a boycott "would have to be worldwide" for it to work. "No one country could affect them the Libyans by having a boycott," Reagan said last month after former president Nixon proposed an economic boycott. Continuing to buy the oil also "involves a particular balance of interests" for this country, Meese added.

In this view, Libya could find plenty of other buyers for its oil in Europe and Asia. Indeed, officials say that sounding out American allies privately has clearly indicated there would be little or no support for joining any U.S.-led boycott of Libyan oil. Aside from their need for oil and good relations throughout the Arab world, the Europeans reportedly have said that using oil as a weapon is a bad precedent, one that the United States objected to after the 1973 Arab-Israeli war and that was opposed by Europeans in the Iran crisis of 1980.

Many Europeans, officials here report, "also feel that we are too hung up on Qaddafi and make too much out of him." That view is echoed by some U.S. officials and constitutes a second line of argument.

"Is Qaddafi worse than the Soviet Union?" one official asks. "The Soviet Union is a real threat to the survival of the United States and we trade with them. Qaddafi is just a pain in the butt, especially to his neighbors. He is no military threat but rather a threat to subvert neighbors."

In a way, he said, public attention to Qaddafi by the Reagan administration may have gotten "out of hand, where he becomes a symbol, like El Salvador, of everything evil. So a lot of people would argue that we have vastly overblown Qaddafi as a person and as a threat."

Many specialists say that at the moment, the United States clearly could get along without Libyan oil, though the situation could change if Saudi Arabian production continues to decline. Some argue that if necessary the United States could eventually buy more oil from Nigeria, a friendly country that is having trouble selling its high-quality crude. They acknowledge, however, that switching suppliers is not as easy as it sounds.

Nevertheless, in the third view it is a sham for the United States to condemn Qaddafi verbally without taking overt sanctions against him, such as an oil boycott, even if they are inefficient or hurt American business or energy interests. In this view, it would also improve the image of American backbone among important African and Middle East opponents of Qaddafi in Egypt, Saudi Arabia, Sudan and several other African neighbors.