Johannesburg — Does television corrupt or educate? It is not a new question. But it has particular relevance in South Africa, where the introduction on New Year's Eve of a new television service aimed exclusively at blacks is being viewed with a mixture of delight and suspicion.
When the chords of the hit song ''Aquarius'' pound into black homes to kick off the new service, many blacks will wonder just what is dawning before them:
Is it an age of heightened white government propaganda laced subtly between soap operas and soccer matches?
Or will it be relatively harmless entertainment long overdue for blacks, who, if they could afford it, have had to watch ''white'' television for the past six years?
''Credibility is everything to us. If we put out government propaganda we will have no credibility at all,'' insists Robin Knox-Grant, director of the new black service for the South African Broadcasting Corporation (SABC).
But suspicions arise in other quarters: ''Black television is just one of the government's tools to enforce ethnicity,'' charges Mike Maisela, director of research at Coordinated Marketing, Ltd.
The service will be broadcast in five traditional African languages: Zulu, Xhosa, Sotho, Venda, and Tswana.
Eventually there will be two black television channels, but at first the two services will share a channel. Total programming time will be 27 hours per week. At the outset, black television will be aimed at a primarily urban audience in South Africa's five major metropolitan areas.
The way Maisela sees it, the use of African languages is an attempt by the government to reinforce its policy of separation of the races. English - the language used by most black newspapers and by blacks when they gather from various regions - will not be allowed on the new network.
SABC programming, particularly news, is substantially controlled by the government, say a number of communications analysts. SABC reports to Parliament through a Cabinet minister.
Knox-Grant rejects the notion that SABC marches to government orders, but he agrees it ''does tend to reflect government thinking.''
In economic terms, much of the black population is underdeveloped. This gives television - one of the most advanced forms of communication - potentially great significance, says communications expert Thomas de Koning.
Mr. de Koning, a professor at Rand Afrikaans University, says that in South Africa, television for blacks cannot help but ''enter the political sphere.'' Television will inevitably, regardless of government intent, ''speed up the process of acculturation and Westernization of blacks,'' he says.
The result: ''Urban blacks will question their position more and more and there will be more discontent,'' Mr. de Koning says. He sees television causing a greater cleavage between rural urban blacks. This, he says, makes it imperative that the government grant urban blacks some type of ''political accommodation.''
Government policy now is to view all blacks as having political rights only in their rural ''homelands,'' regardless of whether they live in those homelands.
The content of black television will be slightly different than that offered on the split English-Afrikaans service.
As with the white service, ''Programming for blacks will be sophisticated and Westernized,'' Knox-Grant says. But at the SABC studios, an official says black tastes require programs with ''more sports, more music, a less formal presentation, and a morally more strait-laced approach.''
The emphasis is on entertainment, but some would like to see the black television service take on a greater educational role. As it is now, black programming ''is based entirely on a first-world model while South Africa is a mixture of first and third worlds,'' says Dr. John Van Zyl, a lecturer in film and television at the University of the Witwatersrand.
Mr. Van Zyl would like to see subjects like agricultural development, health care, basic education on black TV.
SABC has high hopes commercially for the service. It estimates over 200,000 blacks now own TV sets, and it expects 4 million to watch by the end of 1982. If it attracts that many viewers, TV-set sales will shoot up, as will other consumer goods. Recent newspaper ads tell a way to ''enjoy television without electricity.'' The ad promotes portable power generators, an apparent reference to the sizable number of black homes that do not have electricity.