THE DOCUMENTS released last week concerning the Nixon administration's pressures on public television only substantiate what people already knew: that Mr. Nixon and his White House staff wanted public televsion to reflect as exactly as possible their view of the world -- and did everything they dared to make that happen. They were were only partially successful before the Watergated affair diverted their attention. But that half-completed campaign still haunts the world of public broadcasting.

This is what animates the Carnegie Commission's recent proposal to reorganize the national superstructure of public broadcastion. The members believe the Nixon attack not only exposed what could be a great weakness in the Corporation for Public Broadcasting, but also left scars that have defaced the corporation's work ever since.The commission, like many individuals in the television business, thinks the corporation yielded too readily to political pressure when it canceled most public-affairs programs in an efort to secure federal funds for the rest of its programs.

The commission's key proposals are 1) to extend to nine years the terms of the people charged with setting public broadcasting's basic policies and 2) to create a second board of directors to supervise programming. It believes these changes, along with others, such as almost-automatic funding, would create an environment in which politicians would find it difficult to influence the content of the programs that professional employees create or purchase.

There is something to be said for these proposals, although it is hard to find the perfect balance between independence and public accountability in a communications system that is financed in large part from tax revenues. Absolute independence, which is what the broadcasters would prefer, would put a lot of unchecked power over public opinion in the hands of those who run public broadcasting. It was Mr. Nixon's view -- and there are plenty of responsible people who agreed with him -- that public television had acquired too much autonomy and had become politically self-indulgent and frivolous before the White House attack began in 1971. On the other hand, too much accountability and too severely limited autonomy create the danger -- as suggested by this new batch of Nixon administration papers -- that public broadcasting might become a political and propoganda instrument by whichever group of politicans could maneuver most adroitly.

The basic problem is that public broadcasting is not subject to the kind of checks to which almost all other forms of mass communications must respond. For better and for worse, for instance, the television networks, as well as local stations, newspapers and magazines, are influenced heavily in their programming by viewer and stockholder response. Without viewers, or with unhappy viewers, profits drop, and management and programming are changed.

While the absence of this kind of discipline on public television and radio may be vital to fulfilling one of their missions -- that of providing specialized and experimental programming -- it also represents a void that something else must fill. Taxpayers who put up the money are entitled to some measure of control and some assurance that the broadcasters are not simply going to move off into ever narrowing circles of political and social idiosyncracy.

The Carnegie Commission is right in concluding that public broadcasting needs more independence from political pressure than it enjoyed in the early 1970s. The Nixon White House's attempt to force changes in its policies was too successful.But whether it needs to be as blissfully free from direction as the details of this commission's report recommend is something else again. We think not. In passing a reorganization bill, Congress should come down somethwer in between what we have now and what the commission recommends.