A heated debate is raging in the inner sanctum of the ruling, Afrikaner-dominated National Party over the future racial policies and political system of this bastion of white rule.

The fierceness of the debate, with top Afrikaner ministers challenging and denouncing each other in public, has shocked the country and given rise to speculation that that struggle betwen the party's Verligte (liberal) and Verkrampte (arch-conservative) wings may end by shattering the hard-won and much-cherished unity of Afrikanerdom - the bedrock of the entire white South African political system.

Even the powerful Broderbond , the secret brotherhood of Afrikanerdom's most divided over what changes, if any, South Africa should make in an effort to meet the black African and international demands for a new racial and political deal.

A sehism within the National Party could open the way for an overall realigment of white political forces, with the Verligte wing joining forces with the various liberal opposition kparties. But the opposition is at present so weak, badly fragmented and demoralized that the likelihood of such a development seems slim.

The official opposition United Party, which ruled South Africa before 1948, has no strength left and is dissolving itself this week. So is the tiny Democratic Party. The remnants of the two form a new party in a possible step toward a united liberal front.

The National Party's liberal wing has just come out in the open with a plan for establishing a Swiss-style confederation grouping all the peoples presently living in the "white" areas of South Africa - the 4 million whites, 2.5 million "celoreds," 750,000 Indians and eventually perhaps even the 9 million blacks.

Each racial group would be given a large degree of autonomy over its own affairs in separate parliaments but would also share in decision-making on "common issues" in a super-cabinet at the national level. Independent homelands like the Transkei would still be set up for the other half of the black polulation, but all forms of racial discrimination would be abolished inside the confederation.

The conservative wing, on the other hand, is insisting on pushing the National Party's official policy of apartheid through to its logical conclusion - the total political and racial separation of all the country's diverse polulations, including the establishment of homelands for even the "coloreds" (people of mixed race) and Indians and the maintenance of most so-called petty apatheid measures.

The clash of Afrikanerdom's titans over the future of South Africa has taken on added importance since the start of an undeclared race for the succession to Prime Minister John Worster.

While the 61-year-old Afrikaner leader had denied any intent to step down soon, speculation over his health and possible retirement is rife. In any case the outcome of the struggle over South Africa's future racial and political policies is bound to decide whether the Verligte or Verkrampte wing of the party will nominate the next prime minister.

The main candidates for the top leadership post include P. W. Botha, the defense monister; Connie Mulder; the information and interior minister; P. C. J. Koornhof, the controversial minister of sports and national education; Adries Treurnicht, the outspoken deputy minister of Bantu (African) administration, and R .F. (Pik) Botha, the new foreign minister.

The debate over racial policies and the political system has polarized recently around Koornhof and Treurnieht, the former being the leading light of the Verligte, or "enlightened" faction and the latter standing as the Verkrampte champion of apartheid, the guiding policy of the Nationalist since they took power here in 1948.

The outcome of the struggle is uncertain, and the forecasts of knowledgable politicians vary widely.

Some Verligte spolesmen, like Cas de Villiers, director of the liberal Afrikaner "think tank," the Foreign Affairs Association, sem confident of victory.

"There is a mood for change in our country," de Villers said in an interview. Even the right-wingers will accept the proposed changes when the alternatives - too ghastly to comtemplate - are considered. "It is no longer a crisis of survival" he added.

He estimated that 30 per cent of the Nationalist Party's 123 deputies in parliament fall already into the Verligte camp and another 30 to 40 per cent of them are "potentially verligte". The vast majority of Afrikaner businessmen and academicians were also on the liberal side, he said.

"I think we can sell a Verligte policy if it is responsible," deVilliers said. "I'm going to make a guess, but I'd say we can sell it to 70 per cent of theAfrikaner polulation.

Other local observers of Afrikaner politics are convinced that the political winds are blowing precisely in the opposite direction - toward the Verkrampte camp. They point to the recent public posturing of both Vorster and Mulder who have felt oblged to be seen siding publicly with Treurnieht, even though he is only a junior minister in opposition to the Koornhof line of thinking.

Treurnicht, these observers say, could not be speaking out so openly and boldly unless he were confident of gaining majority support for his views inside the National Party.

A similar viewpoint has been expressed in the Afrikaner newspaper Vaderland, widely regarded as the mouthpiece fo Mulder, who as leader of the National Pary in the Transvaal commands the biggest block of voters in the all-powerful party caucus.

The newspaper noted that "right-wing winds are blowing strongly among Afrikaners and the prevailing attitude is "Halt now, concessions are not helping us at all." He concluded that Treurnicht and his supporters had the majority now in the party caucus.

Whether even an ethnically based confederation like what the Verligte Afrikaners are proposing would satisfy the majority black population, or the highly critical outside world, remains to be seen. But it appears that this is the most changes that can be expected rom the political debate now under way among top Afrikaner political and intellectual leaders.

Because the race for party leadership is under way the statements of the various ministers are being analyzed, attacked or defended in a special light. At the same time, it appears some of the contenders are as much posturing to rally support for them selves inside the party as they are interested in debating alternatives to South Africa's internationally condemned apartheid policy.

For instance, Mulder has publicly sligned himself recently with the Verkrampte champion, Treurnicht, because Mulder is suspected in some right-wing Nationalist circles of being "too liberal," while Foreign Minister Botha is making supernationalistic statements in defense of white South Africa in the United States partly because he too is regarded as excessively "verligte" inside his own party.

Botha's spirited attacks on the apparent U.S. demand for the application of a one-man, one-vote policy here as a "commitment to suicide" for whites has earned him high marks in almost all quarters of the Afrikaner electorate. He is now perceived as the Afrikaner David standing up to the American Goliath, a helpful image for a newcomer and dark horse in the race for the permiership.

Whether any major changes will be made in South Africa's apartheid policy as a result of the debate in the National Party is still uncertain and probably will not become clear until this fall when a Cabinet committee established last year to examine alternatives presents its recommendations to a series of provincial party congresses.

Nonetheless, the blurred outlines of the Verligte wing's proposal for a "new deal" in South Africa are already beginning to emerge, thanks to a storm-provoking speech by Sports Minister Koornhof at an international conference on plural societies last month in Cape Town.

Koornhof, who is engineering the slow breakdown of segregation in sports here, suggested that South Africa give up the British-style parliamentary system and adopt some "variant of the Swiss system" of semi-autonomous cantons linked in a loose confederation. In deliberately obscure academic language (he holds a docteorate in social anthropology from Oxford University), he spelled out his notion of how a system of "plural democracy" might be set up in South Africa with an "over-arching institution" allowing for "cross-ethnic or cross-community decision-making."

"In a nutshell," he said, "a policy of plural democracies . . . is a coalition of autonomous and mainly territorially based units cooperating within a political system provising for "consensual decision-making" at both the group and national level.

"Autonomous institutions will allow each unit to handle the everyday needs of individual members. National institutions will provide for the coordination of collective byt consensual decision-making in matters of common interest between the groups."

While Koornhlf said his plan concerned mainly the whites, "coloreds" and Indians of South Africa and would not include the independent black homelands, he hinted at the inclusion of the nine million blacks now living inside the so-called white areas.

"There is a school of thought in South Africa which believes that these blacks, as separate communities should also be utimately phased into the cultural pluralism orbit," he said. "Politics especially in these times are unpredictable and only time will prove whether this line of thought is feasible or not."

The Koornhof speech caused an up-roar in conservative Afrikaner circles, particularly over his suggestion that blacks might one day participate with whites in decision-making at the national level. Treurnicht took the lead in defending the Verkramptes' sacred cows against Koornhof's blasphemy.

Speaking two weeks ago at a conference of the South African Bureau of Racial Affairs, one of the Verkrampte's main "think tanks," Treurnicht said the only changes acceptable were those aimed at speeding up the process of political apartheid.

"We do not want to sit in a Parliament with representatives of other peoples who can destroy the sover-eighty of the whites by majority vote," he said. "We are not even prepared to seat the representatives of smaller peoples ("coloreds" and Indians) in our Parliament, and therefore we are leading them along the path toward their own Parliaments which will have full authority over their own people."

As for the nine million blacks living in white areas, they would have to look to their emerging homelands for the fulfillment of their political and citizenship rights.

In effect, Treurnicht gave a loud "no" to all the key Verligte proposals: a super-cabinet of whites, coloreds and Indians participating in joint decision-making, and the coming together of all groups, including eventually the urban blacks, in a Swiss-type confederation.

At the same time all Bureau of Racial Affairs ideologists are even propagating the idea that the Indians and "coloreds" should have their own separate homelands like the blacks and be totally banished from the white political world.

Whether the liberal or arch-conservative wing of the National Party will prevail in the political and ideological battle is very much in question.

Koornhof and other leaders of the Verlighte wing, seem confiden that the internal prtssure of black unrest and the external influence of the Communist world and Western powers give them the advantage.

Interviewed in his Cape Town office last week, Koornhof said he felt a proposal for national power-sharing at least among whites, coloreds and Indians would emerge from the current deliberations of the special constitutional Cabinet committee. He said that the key to pushing through such a proposal would be getting a consensus among Afrikaner leaders and that he was now actively engaged in the process of "consensus building."

"If there is a consensus at the top, then the bottom [of the national party] will follow," he predicted.

Whether a consensus will be reached on what the Verkramptes regard as a heresy in the apartheid ideology depends, in the view of Koornhof and many other Verligte leaders, on what position Prime Minister Vorster ultimately takes.

Vorster so far has seemed more anxious to preserve Afrikaner unity in this time of crisis for South Africa than to take sides in the battle. He is said to be extremely concerned about his role in Afrikanerdom history and anxious to avoid being marked as the man who oversaw the "great divide" among Afrikaners after 30 years of uninterrupted rule.

To the minority English-speaking white population of South Africa, the whole debate within ruling Afrikaner circles has a slightly surrealistic appearance. Basically, it has very little meaning to the "90 per cent of the polulation (that) is standing by watching in a detached and somewhat mystified way," the Rand Daily Mail remarked in an editorial.

"To this great mass of outsiders the thing looks supiciously like the beginnings of a power struggle to determine the succession of the leadership," said the newspaper. "But be that as ti may, what is really significant is that as the argument develops the theme of it is becoming more and more Verkrampt .

"Indeed, it has ceased to be the old contest between Verkramptes and Verligtes : now it is just between two different brands of verkremptheid [conservatism]. It seems that any king of real verlightheid [enlightenment] in the National Party has been annihilated."