To paraphrase Jean-Jacques Rousseau, in the beginning there are ideals. Society interferes, and scruples are corrupted. As Costa-Gavras might have expressed this philosophy is his latest melodrama, "Mad City": When we get started in our professions, we're ready to change the world, to make it a better place. We become callused and begin to look out only for Number One. The character in "Mad City" who best illustrates this is Mia Kirshner, in the role of Laurie, an enthusiastic intern with a local California TV station. Laurie, who is bright, spirited, and very young, is in love with her job as a budding broadcast journalist and more than willing to attach herself to a mentor she naively believes to share her interest in the Pursuit of Truth. In short order she becomes disillusioned with the possibilities of her medium while at the same time develops the hard shell of a woman who knows what she really wants: to zoom up the career ladder and carve out a niche for herself in a most lucrative profession.

Costa-Gavras, a director whose sympathies have always been firmly on the left of the political spectrum, jolted the film world in 1970 with his third film, "Z," a stunning indictment of the military junta which was at that time ruling his native Greece. At that time Costa-Gavras seemed to be believe he was standing at the historical moment in which movies themselves could transform history. Ironically enough, the famed director, born Konstantinos Gavras in 1933, seems to have turned cynical himself, no longer believing that his products could be much more than entertainment, however thrilling. With "Mad City" he continues the downhill move signified by such ordinary diversions as "Hannah K.," "Betrayed," and "The Music Box." "Mad City," an indictment of the TV news industry, has its moments, but because Dustin Hoffman and John Travolta do not themselves seem engaged by their activities and because the action of the film often seems like a photographed play taking place largely within the confines of a museum, the film, while believable, fails to captivate. What's more, Costa-Gavras does not even educate us about the depravity of the establishment he debunks. Whether we're news junkies or casual followers of the blow- dried anchors who nightly illuminate our TV screens, we digest nothing more than what we already know.

The tale centers on Max Brackett (Dustin Hoffman), a sharp investigative reporter who has been demoted to backwater stories because at one time he publicly ridiculed anchorman Kevin Hollander (Alan Alda). (A flashback midway into the movie portrays Hollander as an egotistical seeker of high ratings who grills reporter Brackett very specifically about the content of body parts which have flown hither and thither after a airline accident.) When Brackett is assigned to interview Mrs. Banks (Blythe Danner), the director of a museum which has fallen on difficult financial times, he stumbles upon an incident involving a former security guard, Sam Baily (John Travolta), who has been laid off from his job and who, entering the museum with a shotgun, compels its director to listen to his grievances. What seems at first an interesting, though unexceptional event, turns into a national phenomenon involving the rapt attention of the American public.

Seeking to exploit the protests of the previously honest and intellectually vacant security guard, Brackett coaxes his station to give him a live, nationwide hookup, which allows him to present the human side of the unfortunate gunman. Every technique of the TV industry is marshalled, including reportage of polls--which show that a majority of viewers have become quite sympathetic to the felon. Rejoicing in his newly-found fame as a TV journalist, Brackett becomes Baily's adviser, insisting that Baily make substantial demands on the police forces which have gathered outside the museum and becoming, in effect, a strong segment of the story. As hawkers gather to sell souvenir T-shirts with Sam's picture, clashes develop between the FBI and the local police chief and between anchorman Hollander and reporter Brackett for ownership of the story. Meanwhile Laurie tracks down the felon's mother to broadcast an interview largely sympathetic to Sam, who has by now become the taker of hostages, largely children, and who has accidentally shot the man with whom he had worked.

"Mad City" fits in with several other movies which have taken their pleasure in exposing the debauched underside of American institutions. "Critical Care," which opened at about the same time as "Mad City," satirizes the hospital industry, which is far more concerned about the financial health of its patients than about their well-being. Just recently, "Devil's Advocate" unfolded a scenario in which a brilliant lawyer begins to question the ethics of defending people whom he knows are felons. Years back, "The Hospital" turned a serious situation into Marx-Brothers comedy while "Network" exposed the TV industry's willingness to do anything to increase ratings. "The Big Carnival," Billy Wilder's 1951 film about an embittered reporter who seeks the brass ring by exploiting a human interest story, was a more biting story than "Mad City," one which featured superior acting by Kirk Douglas and Jan Sterling. Perhaps the passage of time has made us all so cynical about the banalities of doctors, lawyers, politicians and journalists that "Mad City"--which offers nothing fresh--is simply unable to shake us up.