Two CBS News documentaries airing during Christmas week manage to take viewers on fascinating journeys to nowhere. Both delve into topics of great interest, tease us with tantalizing examples of controversial material, then disappointingly fall by the wayside when the time for a pungent conclusion arrives.
CBS Reports: Don't Touch That Dial (Thursday, Dec. 23, 10-11 p.m.) and a CBS News Special, Eye on the Media: Business and the Press (Saturday, Dec. 25, 10-11 p.m.), have both chosen to investigate matters of great interest and immediacy to most viewers.
Morley Safer, the solidly dependable ''60 Minutes'' standby, goes behind the screens of prime-time television. ''Don't Touch That Dial,'' produced and directed by Julian Krainin, uses as examples the development, network acceptances, and premieres of NBC's ''Family Ties'' and CBS's ''Seven Brides for Seven Brothers.'' Some poignant and some repugnant candid moments of compromise are recorded for posterity.
Mr. Safer asks the right questions of producers and network executives. He gets the standard answers, too - the network insists it interferes only as much as is necessary; the producers insist that networks demand changes that weaken the shows, then reject the shows because they are weak.
The major conclusion of this glossy documentary, which seems to emulate too much of the slick prime-time style it denigrates, is enunciated at the end by Mr. Safer. ''It is no easy thing to speak in any definitive way about this art or science or money machine that is network television. There are (fortunately) no rules about what television should be like. The people who run things are not paid to put quality, whatever that is, on the air; they are paid handsomely to put success on the air.''
So what else is new?
''Eye on the Media: Business and the Press'' jumps right into the business-press fray, flailing in all directions, putting on a good show, but reaching no real decisions. It's a bit like a match between a boxer and a kangaroo, with each side taking turns being the kangaroo.
Edited down from a three-hour seminar sponsored by CBS News and Columbia University , this CBS News Special purports to investigate journalistic ethics - especially ''60 Minutes''-type ethics - in preparing stories that concern consumer products. Does the interviewer have the right to entrap the interviewee? Is it the network responsibility to present positive as well as negative facts about a product? How far should Mike Wallace or Dan Rather or even Geraldo Rivera (all of whom take part in the discussion) go to get their story?
All perform under the expert gadfly-like guidance of Harvard law professor Charles R. Nesson. Dan Rather, in particular, comes across as a clever down-home reporter, constantly gauging the probability of things by whether or not you believe that thunder curdles milk.
If there is anything like a conclusion amid all the marvelous professional repartee, it comes from Mr. Taylor of the Wall Street Journal, who concludes that the ''60-Minutes'' kind of confrontational reporting is ''marvelous drama and has very little to do with journalism a good share of the time. . . . I'm not saying they shouldn't be on television. What I'm saying is it's not journalism.''