THE ARGUMENT within the Reagan administration over Africa policy is hardly over, but the administration has given a certain pause to some of those who had feared it was forsaking the black nations and rushing into a strategic embrace of South Africa.

It has, for instance, made a generous pledge of aid to Zimbabwe, southern Africa's Exhibit A of multi-racialism in a democratic context. The sum pledged -- $75 million a year for three years -- was a good bit more than the Carter administration had been able to pry loose, and it gives the United States a respectable place in the network of governments and banks planning to throw a $2-billion life ring to President Robert Mugabe. Mr. Mugabe, in offering thanks, indicated with evident relief that the administration had not so far gotten so close to South Africa as to have made "a choice," one he hopes it will not make. He was speaking just as President Reagan, in an interview with this newspaper, said he would be moving to improve relations with black African states.

In that interview, Mr. Reagan was ready with a response plainly intended to ease African fears that he might ditch the international negotiations that had brought Namibia to the verge of elections and, instead, support an attempt by South Africa to seat its own client regime. He did propose a new negotiating wrinkle -- writing a constitution before elections. But at face that would seem merely to bring Namibia into line with the transition example set successfully by Zimbabwe and, perhaps not incidentally, to Reaganize a Carter negotiation.

Neither of these developments disposes of the central question of the value the administration will finally place on strategic and economic partnership with white South Africa. It improves the atmosphere, however, for Mr. Reagan to solicit the friendship and understanding of black Africa and for the State Department to be folding black Africans into its policy review. Last week the secretary of state received for 3 1/2 hours the foreign minister of Nigeria, whose oil, markets and influence epitomize the #iReallpolitik argument for close ties with black Africa, and his assistant for Africa is about to pay calls in key black-ruled countries, plus South Africa.

Obviously, this administration -- in this respect like the last -- would like to have its cake and eat it too: to enjoy good relations, variously defined, with black Africa and with white Africa. Diplomatically, the question is whether the degree of anti-apartheid committment demanded by the black states is compatible with two tendencies evident in Mr. Reagan's Washington. One is to define the American strategic interest more in terms of South African than black Africa, and the second is to resist the notion that, as Robert Mugabe carefully warned, if the United States gets too close to South Africa it will have made "a choice" in black Africa's eyes. That argument over strategy is familiar, and it will go on.

What is less familiar but perhaps no less important is the argument over how the United States can best contribute, if at all, to the internal evolution of South Africa. Roughly speaking, the Carter answer was to keep the heat on, to identify the United States openly with black aspirations for one-man/one-vote, and to accept certain limits on official ties with the white minority regime. The Reagan answer is not yet in full view, but in his statements the president has expressed more understanding for the white minority that is under pressure to yield power than for the non-white majority that abears the brunt of apartheid. He is, moreover, more optimistic than most white readiness for change.

From this perception of white readiness appears to flow his view that "rather than just holding ourselves completely aloof and distant, we can, because of our own [racial] experience here, be of help to them in resolving their problem." Many white South Africans lap that proposition up. Black South Africans tend to wince. In any event, it is a tall order and it needs far more scrutiny than it has so far received.