The political leaders of South Africa's tough, Puritan-like white tribe are lowering some of the most irritating racial barriers blacks face here, but they will stand firm on the basic structures of this country's deeply entrenched system of segregation.

That decision, reaffirmed in a series of policy statements gives in interviews by senior ministers in the white government, is provoking rising white dissent and black rage here.

For the first time, a significant part of the dissent comes from within the leaders' own tightly knit community of Afrikaners, as the modern descendants of the Dutch-speaking Boers who began settling here 300 years ago are known.

The National Party, the Afrikaner based white political party that rules here, came to power in 1948, the same year that Strom Thurmon ran as a segregationist Dixiecrat for President. If Thurmond had won, and the Dixiecrats had been reelected every four years since, the result might well resemble what is happening in South Africa today.

Carefully controlled by any outside standards, both the hestitant changes and the demand for faster movement are testing the treasured tribal unity of the Afrikaners, whose violent history of frontier conflict and siege on South Africa's plans has conditioned them to suppress self-doubt and non-conformist actions.

Along with South Africa's vast natural store of gold, diamonds and uranium, a temperature climate and a developed industrial base, it is the Afrikaner that makes the country different from the rest of the continest.

While English and French settlers negotiated turnovers to black rule to the north, the Afrikaners have dug their heels in. They have developed the technology to build an atomic bomb to enforce their self-ascribed "mission" to stay, and may already have the bomb.

Numbering 2.3 million in this land of 26 million, the Afrikaners emerged only three decades ago from rural solitude and deep poverty to take control of South Africa and fashion white power into an enduring force based on the Bible and the gun.

Now an urbanized business and intellectual class that has formed inside this rough-hewn tribe during its three-decade rule is trying to add the balance sheet and international respectability as tools of Afrikaner control and, in their own eyes, survival.

The uneven contest being waged inside Afrikanerdom is one of conflicting visions of what it means to be "Western" and white at the southern tip of this continent in the last quarter of the 20th century.

Power is concentrated in the hands of Afrikaners who, generally speaking, stubbornly resist fundamental change in their "traditional way of life" - the code language here for officially required segregation and keeping blacks politically powerless.

They define "western" as it was understood elsewhere is the world 30 to 40 years ago - white supremacist, intolerantly Christian and morally rigid, at least in public matters.

There is genuine puzzlement and a feeling that other white-dominated nations are being hypocritical when they suggest that "Western" today is a secularized, formally democratic expevience committed to ending official racism.

Andrew Young, who visited this regian shortly before being named the first black American ambassador to the United Nations, says that the Afrikaners "remind me . . . of the old Southern Baptists, there's this awful familitarity," he met while "traveling in Mississippi or Louisiana or Georgia when I was a child."

The Afrikaners are in fact the globe's sternest Calvinists, called by one of their leading academics a people "who got stuck in history" and by another writer the historial siblings of "the Anglo-Saxon revoluntionary puritans of both Old and New England."

Their name conveys the essential contradiction of their historical existence. These white assert that in fact they are African, a term most of the rest of this continent and the world consider a synonymous with blackness.

In the solitude of the Boers' farms in South Africa's quiet interior, "The Afrikaner missed the lessons of the 19th century about liberalism and equality," says English-speaking Professer Julius Lewin. "He emerged into the 20th century as a modern man and wears that label because he knows how to make money."

The Afrikaners have president over the rapid growth of a modern economy that has drawn increasing numbers of Afrikaners and black Africans into the cities, provided both with class structures that their previously egalitarian rural societies lacked, and brought them into jarring daily contact absent on the farm.

The National Party government installed "apartheld" - "separateness" in their language, segregation to the rest of the world - to restore white control and separation from blacks.

The limits of change in that system are largely defined by the rural past and its rough, raw distrust of liberal attitudes, big business and the now politically powerless 2 million English-speaking whites, 2.5 million people of mixed race and 18 million blacks.

But out of the social transformation of the Afrikaner community, a newly established business and intellectual class is growing to set the limits of dissent for the community.

They argue that the Afrikaner and his particular culture can best survive by adopting a broader definition of "Western." To do this, he must drop the most obvious features of racial discrimination and offer a fair deal to urban blacks and persons of mixed ancestry caught on the wrong side of the color line.

"We must make it possible for civilization to survive in South Africa," the Afrikaners newspaper Die Beeld editorialized recently. "For this we need the cooperation of our black and brown countrymen - and we will not obtain this by pushing them away from us on every conceivable point."

Their efforts are already contributing to ripples of change that, when measured by the formerly static world of the Afrikaner when it came to race relations, take on tidal wave proportions here.

"Segregation for segregation's sake doesn't make sense," said Prof. Gerrit Viljoen, the new head of the once reactionary, powerful and secret Broederbond organization, which originally developed apartheld but is now drifting toward the liberal position in Afrikaner racial politics.

Apartheid "is not an ideology nor a dogma. It is a method, a road along which we are moving," and subject to fundamental reassesment, he said in a rare interview.

This dichotomy - some Afrikaners would say struggle for the tribe's mind - within Afrikanerdom is producing a split-level approach to prejudice that is disorienting for many in the white working class, who increasingly appear confused over exactly what attitudes their government is calling for toward blacks.

The National Party government has begun to say for the first time that racial discrimination is wrong. While it continues to shut black people out of schools, buses, toilets and 90 per cent of the country's hotels and restaurants, allegedly because of their different "nationalities" rather than the color of their skin, the government is establishing a climate of acceptance by letting a few politically non-vital barriers fall.

The government let a city council controlled by the opposition United Party desegregate public park benches and libraries in Johannesburg. A handful of expensive hotels and restaurants can serve Africans under certain conditons, if they want to. Three theaters in Johannesburg, Cape Town and Durban have been opened to mixed audiences. Elevators are no longer "white only," and post office entrances and lines have been desegregated.

The changes affect petty apartheid - the set of restrictions imposed on blacks who come into daily contact with whites because of their jobs. "We can have an integrated economic population in the context of the commercial core of an urban area," a National Party spokesman said.

Interviews with five senior Cabinet ministers and other officials establish however, that the government will push ahead with grand apartheid, the radical vision of smashing South Africa in its present political form to save it and to preserve white power here.

These key ponts emerge from interviews and discussions with leading Afrikaners figures of dissent:

As long as this government is in power, no black in South Africa will be able to buy a home or piece of land outside of black-only ghettos or "homelands," be free from the threat of arrest for not carrying a government-issued "reference book" that whites are not required to carry, or vote in an election with whites.

Officials hope that U.S. President-elect Jimmy Carter will focus on the Communist menace they see hanging over southern Africa and the protection they say they afford to the $1.5 billion American investment here rather than on civil rights. If a confrontation develops, however, they leave no doubt they put maintaining their "cultural identity" before their ties to the United States.

The growing questioning of apartheid by Afrikaners is one of two implicit admissions that it is failing to provide the Afrikaners with a "moral alternative" to the use of force in containing black nationalism.

The other implicit, and more important, admission of failure is the escalating violence the government is directing against its black subjects. At least 375 blacks have died this year in confrontations with heavily armed police riot squads, and in some aspects the government has taken on the air of a junta rather than the Westminister-style cabinet it says it is.

Rebaptized "separate development" because of the international stigma attacked to its original title, grand apartheid mandates the physical exiling of all 18 million blacks from the 87 per cent of the country declared to be "white territory."

Nine tribal reserves are to be carved out of South Africa and transformed into independent states to "satisfy the national aspirations" of all blacks, including the 6 million to 8 million who will remain in white South Africa as "foreign workers." One homeland, Transkei, was given a grant of independence in October.

Fully implemented, separate development would shift to the extremely vulunerable homeland governments many of the onerous tasks of apartheid. And it would, say Afrikaner intellectuals, cleanse the Afrikaner community of the guilt that is building up over the black man's plight in white-ruled South Africa today.

White power is wielded by the Cabinet, largely to benefit the Afrikaner farmers, railway workers and lower-level civil servants, who form not only the heart of the National Party's electorate but also the only substantial white working class that sub-Sahara Africa has ever known.

While attention is fastened on the growing body-count in black townsships, another statistic also holds major importance: Between 1970 and 1976, 20 per cent of the country's 96,000 farmers moved off the land into urban areas. Nearly all of those who left were Afrikaners. So were those who remained.

This continuing but incomplete transformation accounts as much as outside pressures do for the unsteady balancing act done by the Cabinet headed by Prime Minister John Vorster as it attempts to assess its electorate's center of racial gravity.

The Cabinet reflects many of the aspects of the uneven development of Afrikaner society under the pressures of rapid industrialization and racial change elsewhere in the world. Mixing the fervor and stolidness of backwoods evangelists preaching to city folk, Vorster's senior ministers praise change in one breath and then remind visitors that it can be overdone.

"This country has as free a press as any country in the world," says the Minister of Information, Connie Mulder, in a country where at least a dozen black journalists were held by police without charges for much of last year and where hundreds of publications were banned in 1976.

"None of these newspapers support the National Party," he said of the English-language press. "I don't think France or Germany or even the United States would have put up with this kind of thing, even during the Watergate affair. Why here, we proceed as if there was a permanent Watergate . . . even though we have not reached a crisis situation.

"Mulder's deputy, Louis le Grange, explains why his constituents in the politically important and conservative town of Potchefstrom will always demand that blacks live in segregated housing compounds in urban areas:

"We did not take any land from anyone else. We live on our land, If Afrikans could buy houses in our areas, the white chap with money would just move out and buy a house 20 to 30 miles away. It would create a mixed cultural society, which we won't accept, and it would mean that the poor people would be left living apart form the rich people who could afford their separateness."

Justice and Police Minister James T.Kruger tells a reporter that his riot police turned down protective equipment and clothing when confronting student demonstrations because "Their boots were already too heavy when they were chasing people who are barefoot," and replies to an American official who suggests that Kruger meet with a moderate urban black leader to arrange a truce with the students:

"I won't see him. I know what he will say.I'll see him only when he is ready to sit there and listen to what I have to say to him."

Kruger and Mulder are generally considered to be the two most important men in the Cabinet after Prime Minister Vorster, who declined to be interviewed.

Asked in interviews about the fundamental laws of apartheid, Mulder, Kruger, Le Grange, Economics Minister J.C.Heunis and Sports and Education Minister Piet Koornhof gave statements of policy that appeared to establish more clearly than before the limits of the "moving away from racial discrimination" that the government has committed itself to in speeches in the United Nations.

"We've always had different residential areas, and we're not going to change that at all," Le Grange said about the Group Areaese Act, which prohibits blacks and mulattos from living outside defined areas.

"The main pillars on which the South African government's policies are based are not going to deviate. Within the broad setup we can have changes, but the pillars will remain."

The "pillar" most resented by the African majority is the law requiring them to carry a reference book - the modern name for the passbook - that is the heart of the "influx control" system of keeping blacks from settling in the 87 per cent of the country declared white property.

More than 250,000 Africans continue to be arrested annually under the pass laws. Most are jailed or fined and then returned to the jobless homelands. It is illegal for Africans to enter urban areas unless they have the reference book, according to the decrees of a government that encourages white immigrants from Europe to settle in the urban areas.

"Influx control cannot be taken away," said Kruger, who is in charge of enforcing the pass laws. "Perhaps there can be a streamlining, but doing away with it would create too many problems. Africans with 21 wives, each with 10 children, would come pouring in and the housing problem would get out of hand."

Other deeply entrenched laws that senior officials said would not be altered include laws banning interracial marriage and sex, those empowering the government to reserve specific jobs for whites if it so desires, and the disenfranchising of Africans in elections for the national Parliament that makes the laws regulating the blacks' "freedoms."

Interviews with senior Cabinet ministers produced only one expression of willingness to alter a main feature of apartheid - the reservation of so much of the country's land area to whites. A Cabinet official said it might be possible to renegotiate a more equal division once the homelands had achieved independence. But he insisted on not being quoted directly, since a direct statement could touch off "panic-selling of property."

Vorster, who had built up an image of a sure-handed, decisice if stolid leader, is vacillating on the continuing public criticism that one of his deputy ministers, Andreas Treurnicht, is directing at the small movement away from official discrimination that has occured. Treurnicht says no more barriers should fall, despite the government's pledge at the United Nations Vorster apparently does not feel confident enough of the popular reaction to remove or even to silence Treurnicht.

Drift within a Cabinet that has handled the economy clumsily over the past two years and suffered a major political defeat through its involvement in Angola has shaken the confidence of the normally politically quiescent Afrikaner community.

The most radical change in grand apartheid being debated within the government today is, in Mulder's description, "giving" urban Africans "elected councils in the areas where they live, which will have control over their everyday lives."

This will happen "in time," Mulder said. Other officials are discussing a cantonal system of linking the urban areas back into national politics through the homelands. But Mulder stressed that the Africans' higher political aspirations must always be satisfied in the independent homelands and would never be part of voting in white areas.

Business entrepreneurs are a new breed in Afrikanerdom. They are becoming upset at the restrictions apartheid puts on their ability to use capital and labor freely, and at the damage racial disturbances are doing to the economy and the international image of SOUTH Africa.

"The separate development concept has got to be redesigned and redefined . . . We have to find peaceful ways to head off bloodshed," said multimillionaire banker an Marais in the 25th-floor suite of offices over his Trust Bank Cape Town headquarters, which crated a stir in SOUTH Africa a decade ago by allowing blacks and mulattos to sand in line as white clients to deposit their money or write checks.

"Ten years ago separate development would have been 1,000 times more salable if it had been refined then. The longer we wait, the less salable the package becomes," said Marais, who became head of the South Africa Foundation in 1974 and shifted its role away from publicizing almost exclusively the government's view-point to a more factual and questioning one.

Publicly taking issue with the government's insistence that urban blacks will vote only in the homelands Marais said in the interview, "We have to find ways to accommodate the 'Coloreds' and an irreducible number of blacks who can't find any justification for being in the homelands, . . . body should be set up to investigate homelands, what percentage can be justifiably treate as guest workers, and what the residue would be. Then we can discuss federal, confederal, plural or canton systems."

Six years ago this statement could have brought the wrath of afrikanerdom down on Marais' head. Today, after the collapse of the protective Portuguese colonial governments in Angola and Mozambique and black unrest in SOUTH Africa, Marais' concern over "the residue" echoes from previously unlikely quarters, like the Broederbond, or Brotherhood, of Afrikaner notables in politics, commerce and the arts.

Next: Black Power