THE NEW PLEDGE by 12 major U.S. corporations to end segregation and promote fair employment practices in their South African operations represents potentially valuable private initiative. Never mind that it took 18 months of private prodding by General Motors director Leon Sullivan, a Philadelphia clergyman, to get the corporations to swallow their reluctance to do what some South African-owned businesses are already doing. South Africa's economic reliance on foreign investments and markets, and its political and psychological reliance of foreign tolerance if not favor, make it particularly sensitive to the acts and attitudes of the American corporations. The past easy acquiescence of most of them to the practice of apartheid had made no small contribution to bolstering the South African system. The very least that these firms can do at this late date is to begin moving with the times.

One notes that the firm's promise to pursue racially neutral employment practices was at once criticized by some of the church-related shareholder groups who have been the moral spearpoint of change. "It doesn't deal with the larger issues of social change in South African and it places no limits on loans or the sale products there," Tim Smith of the Interfaith Center on Corporate Responsibility told the Wall Street Journal. One can appreciate the feeling, and the tactical positioning, behind such a statement. But we fail to see how corporations can be expected to move forward if each small step they do take is derided as inadequate.

In the long sweep of history, those steps may turn out, in fact, to be inadequate: racial convulsion may yet destroy the American economic stake, and not only the American stake, in South Africa. Faster corporate change, or even "disinvestment" (pulling out of South Africa), may turn out to have been wiser choices. But we think the right tack now is for American companies to use their influence on the side of human rights - for the fair and equal treatment of blacks in the workplace and especially for the training of blacks in the supervisory and technical jobs now commonly denied them.

The Carter administration, proceeding at a pace appropriate to the complexity and volatility of the probalem, had yet to formulate any large new national policy toward South Africa. Whether the United States has the interest and reach to take upon itself a larger and more explicit political role in managing the South African crisis is, of course, debatable. More than that it has yet to be rigorously and fully debated in a way that a national question of these dimensions should be debated before a government policy is formed. In the interim, however, there is a clear need for corporations and other private parties dealing with South Africa to try to work out their own responses. This seems to us what the corporations are setting out to do.