The government of President Pieter W. Botha has fallen between stools. Its reform program has proved too limited to capture black imaginations but extensive enough to forfeit the confidence of hard-line Afrikaner voters.

The result is a devastating combination of black unrest and white backlash which revealed itself in a series of by-elections last Wednesday.

The government appears to have persuaded itself that the unrest is not the result of black anger but is the work of a few agitators. Its solution, therefore, is to use tougher security measures rather than change its political approach.

Statistically, the by-election results should be no cause for alarm. The government has a two-thirds majority over all other parties combined, and computer predictions are that the 17.2 percent swing to the far-rightist parties in the by-elections would enable them to win only six more seats than the 18 Andries Treurnicht's breakaway Conservative Party now holds.

But the Botha government has a deep- rooted fear of seeing its power base in the white Afrikaner tribe eroded. The thought that the far rightist parties may become the new custodians of Afrikaner nationalism's holy grail is a nightmare that the prospect of compensatory English votes cannot dispel.

Botha said he would "take cognizance of why people voted the way they did." That probably means he will move even more cautiously with his reforms, and crack down harder on the perceived agitators.

But slower reforms and harsher action in the townships can only increase black anger, leading to more unrest, which in turn will result in a stepping up of the international sanctions campaign and a further loss of business confidence, causing more economic hardship and more of a white acklash against the government: a vicious cycle.

A leader in Botha's position is bound to lose hard-line support as soon as he declares in favor of reform. If he then moves forward halfheartedly, he fails to win new support from the unimpressed recipients of his reforms. Nor does his tentativeness bring back the hard- liners.

Botha's ambiguity has caused a crisis of confidence in his leadership. The issue now, many believe, is whether a bold quantum leap could persuade black South Africans once and for all that the government really intends to dismantle apartheid. Those who favor such a course suggest it might unfold with this kind of declaration of intent:

1)The government declares its intent to rescind all apartheid legislation within one year, during which it will begin negotiations with representative leaders from all sectors of the community to devise a new nonracial, nondiscriminatory constitutional system.

2)The government makes only one advance stipulation, that it will insist on agreed, permanently entrenched safeguards for minority groups so that apartheid is not replaced by another system of racial oppression.

3)As a gesture of good faith, the government announces the unconditional release of Nelson Mandela and other members of the African National Congress leadership group serving terms of life imprisonment.

4)The government invites the president of the ANC, Oliver Tambo, to return to South Africa under indemnity from arrest to join in constitutional talks.

5)The government hopes the ANC will make a reciprocal gesture by suspending its campaign of violence. The government notes the ANC has always claimed that it turned to violence only because it was deprived of the right to campaign for change by constitutional means.

6)The government announces the release of all persons detained under emergency regulations and the Internal Security Act since the current unrest began and the withdrawal of all charges against them.

7)The government again hopes that the persons concerned will make a reciprocal gesture by using their influence to bring an end to the widespread unrest in the country.

8)The government appeals to the international community, and especially neighboring states in southern Africa, to cease all hostile acts against South Africa and to use their influence to help stabilize the country.

Such a declaration would have a galvanizing effect. Doubtless there would be a further loss of voter support on the right, but many other whites anxious to see genuine reform would rally behind the government.

Black leaders would be certain to respond positively. The level of unrest would diminish, and, with support replacing threats from abroad, business confidence would recover. An improved economic climate would help limit the growth of both white reaction and black extremism.

Those who support this approach do not pretend that a transition to a new nonracial society would be easy. They believe, however, it offers a fair chance to end the present vicious cycle of black unrest and white backlash.