Once again public television, through two stimulating documentary programs this week, manages to bring viewers a wide range of viewpoints on controversial issues. The Paper Curtain (PBS, Tuesday, 10-11 p.m.) explores the McCarran-Walter Act, the 34-year-old law that has been used to to deny visas to would-be visitors to this country if their political beliefs are judged subversive.
Many well-known authors, politicians, and other public figures have been denied entry by a law that, according to one observer in this documentary, was ``passed at the height of the xenophobia of the McCarthy era.''
Some of those denied entry -- Canadian author Farley Mowat, Mexican writer Carlos Fuentes, Colombian writer Gabriel Garc'ia M'arquez, and Hortensia Allende, widow of Salvador Allende, for mer president of Chile -- state their cases on camera. They indicate deep disappointment, even bitterness, about a law they see as designed to keep controversial ideas out of a country that professes to be ``democratic.''
Novelist John Irving, the narrator, makes clear that the orientation of the program is anti-McCarran-Walter. Nonetheless, the show does take account of the views of some of the act's supporters. Officials of the Immigration and Naturalization Service and of the State Department make their cases. In fact, they manage to do so a bit more convincingly than does Roy Cohn, former aide to Senator Joseph McCarthy, who says: ``I think some of the worst trouble the free world has faced has been from words.''
Mort Halperin, of the Center for National Security Studies, takes exception to that idea. He responds: ``The basic principle of the First Amendment is that the free exchange of ideas helps our society, not hurts it. When we keep people out because of their ideas, because of what they say, because of their political beliefs, we are being disloyal to our own beliefs and our own constitutional principles.''
If your appetite for controversy has been whetted, you may alwo want to see Flashpoint: Israel and the Palestinians (PBS, Wednesday, 8-10:30 p.m.). Another in PBS's ``theme night'' programs during which a subject is examined from several partisan points of view, ``Flashpoint'' uses three independent documentaries to look at the bitter and protracted struggle between Jews and Arabs in the Middle East.
Each film is flawed by one-sidedness; each will antagonize those with opposing points of view. Presented by station KQED of San Francisco, the documentaries come with discussions fore and aft, with additional room for local stations to add their own round-table commentary, if they wish.
``Two Settlements: Etzion and Hebron'' combines two short films that reflect the politics of Israel's conservative settlers. ``Peace Conflict'' probes Israel's internal struggles by presenting profiles of Israelis with differing political ideologies. Both of these Israeli-made films make some attempt at balance, even though their basic aim is to present Israeli attitudes.
They are juxtaposed, however, with ``Occupied Palestine,'' a blatant propaganda vehicle for airing vehement anti-Israeli sentiments.
The most recent of the films was made three years ago, the oldest seven. None can be taken at face value, but seen together with the added round-table discussions and commentary, they may help viewers shape their own opinions.