THE MOST INTRIGUING bit of political news to come out of South Africa in a long time is that a discussion has begun among the ruling whites over whether and how to free Nelson Mandela, the imprisoned leader of the main black underground movement, the African National Congress. The government apparently would like to shelve him, after 21 years of a life sentence for plotting the overthrow of the regime, in a puppet black "homeland"; he refuses. But others in the ruling National Party are starting to think, out loud, about releasing him and other ANC figures in order to have an interlocutor with which to discuss the country's future.

Just last Saturday President P. W. Botha declared he had no intention of releasing Mr. Mandela and would not negotiate with any organization that favors change through violence. The interesting thing, however, was that speculation on the matter had reached the point where the government felt obliged to squelch it. Mere membership in the outlawed ANC, after all, has been judged by a South African court to be grounds for high treason. The movement's leaders in exile cannot be quoted in the controlled South African press.

Behind this development evidently lies the government's introduction earlier this year of a new constitution ensuring continued white dominance, offering restricted political rights to the Asian and mixed-race minorities and altogether denying any rights to the 22 million blacks of the majority. The outrage and absurdity of the denial provided what Nelson Mandela's wife, Winnie, herself a "banned" person, described as the "best unifying factor" in years for South Africa's otherwise diverse black quasi-political entities. The resulting unrest forced the prime minister to formulate a flabby pledge to extend some sort of "political participation" to urban blacks. Meanwhile, others of the Afrikaner ruling class are weighing a more urgent and direct approach: dealing with Africans directly through their own leaders.

Nelson Mandela, 66, has been a prisoner for two decades. Just whom he and other known black figures speak for is something that the South African government, by blocking black political expression, prevents anyone from knowing exactly. What is totally clear, however, is that whites cannot ensure any secure place for themselves in their country if they do not admit blacks as fellow citizens whose ultimate destiny they share. Blacks have turned to violence because whites blocked all peaceable options for them. Permitting blacks to speak for themselves would be the essential first step on a different path.