The South African government is once again a day late and a concession short in its drive to forestall the inevitable. Conciliatory words that would have signaled a breakthrough a few years ago come across now as empty justification for the armed repression of the country's black majority.

The repression itself (invoked under emergency powers so sweeping that the press is forbidden even to print the names of those arrested and jailed) might have worked a few years ago to produce at least an uneasy calm. Now it serves only to radicalize the black population, threatening to turn what the government calls "riots" into what it fears most: full- fledged revolution.

The time-tested way of dealing with violent uprisings is to isolate the radical leadership while making serious concessions to the rank and file. South Africa is expert at isolating, incompetent at making concessions. Again and again, it makes concessions only after the thing conceded has ceased to hold even symbolic importance.

It concedes the permanency of its black urban population only after its "homelands" policy, under which, by definition, there would be no black South Africans, has been rejected by the entire world. It offers semi- citizenship to its Asian and mixed-race population, hoping that the blacks will read that to mean "We must be next." With protest building both inside and outside the country, with police-provoked violence resulting in hundreds of deaths, with every funeral of every police victim threatening to launch the revolution, the government offers: what? A relaxation of the official ban on mixed marriages.

Now the offer is for negotiations between the government and the black leadership, negotiations with a view to power sharing. Listen to the government, and you get the impression that such negotiations are all it ever wanted, that the only reason for invoking the emergency powers now in force was to buy a period of peace during which the negotiations could move forward.

But first, you understand, the government must move to protect the blacks who are interested in negotiations from the black radicals bent on murdering them. The South African ambassador-designate Herbert Beukes sought to make that point on ABC-TV's "Nightline" the other night. Fortunately, the Rev. Alan Boesak, one of the brightest new opposition leaders in the country, was also on that show to point out that the blacks being killed by blacks are not "moderates" and bridge-builders but men suspected of being collaborators, informants and quislings.

Negotiations, in fact, may be the way out of the turmoil and injustice in South Africa. The ruling whites cannot be expected to concede voluntarily any principle approximating one man-one vote. But just as blacks in charge of what was then Rhodesia were willing to negotiate a reserve of political power to the white minority, so might the whites in charge of South Africa see the wisdom of negotiating a settlement with the black majority.

The prospects for such a negotiated outcome increase with every acknowledgment, implicit or otherwise, from the ruling white minority that the present situation is untenable, politically, militarily and morally.

The danger is that the government, once again being too clever for its own good, will try to negotiate with its own handpicked "trusties," rendering any agreement worse than useless.

The government knows which black leaders have the confidence of the majority of black South Africans -- men such as Nelson Mandela and Walter Sisulu, imprisoned since the early 1960s, or Nobelist Desmond Tutu, who may be in prison before the current unrest is over.

If South Africa's whites really are ready for peaceful change (as opposed to buying time to retain their absolute power) they know how to do it. The fear is that they will, as has become their sorry custom, do too little too late.