One of the best Washington pollsters, Peter Hart, keeps telling me that the most extensive index of American public opinion lies in the ratings of popular entertainment. So for the past week I have been force-feeding myself on the hit television serials, the socko movies and the people who make and market them.

I haven't discovered the spirit of the age. But clear patterns do show up that suggeest that most Americans view the world and what to do about it in a distinct, even peculiar, way.

The common denominator of all the popular TV shows and movies is the sense that the world is a perilous place full of cataclysms, bad guys and freaks. Films such as "Star Wars," "Jaws" and "Close Encounters of the Third Kind" give intimations of monstrously alien forces lurking everywhere, from the deeps to the cosmos.

The popular - and, I think, quite good - new television serial "Soap" tells of a family that includes a Mafioso, a homosexual, a murderer, a retarded youth and a girl who seduces a priest. "Hawaii Five-O" and "Kojak" and the other popular detective series on television show regular battles against powerful and often deranged criminal elements. A recent installment of "Happy Days," which is supposed to represent nostalgia for the simpler times of the 1950s, turns on the effort of a young nymphet to live down a past in reform school so that she can make it as a pop-music star. I couldn't begin to list the movies with long and harrowing chase scenes. "Smokey and the Bandits," a highly successful new film, is in fact one long chase scene.

Almost all the action is set in the group for which, about a decade ago, I developed the term Middle America. "Laverne and Shirley," another popular TV serial, for instance, recounts the efforts of two Milwaukee working girls to land husbands. The level of aspiration is extremely low. In one recent installment, Laverne and Shirley are trying to raise enough money to take a cruise on a Great Lakes steamer.

Ethnic groups seem to be present in a big way - but largely, I think, to fix the scene in the lower middle class. The Fonz in "Happy Days" has a heavy Bronx accent, and Garry Marshall, who created that show and "Laverne and Shirley," has a car with a license plate that spells out BRONX.

I have yet to see a successful, happy, upper-middle-class family playing a lead role in any of the shows. A family with money in "Soap" includes a wife who thinks "the world should be set to music" and a husband who takes his marching orders from a black butler.

Drama in almost all cases arises out of the efforts of ordinary people to cope with the miserable world around them. Some simply fail. In the fine new film "Looking for Mr. Goodbar," the heroine, who seeks relief from the boredom of teaching by picking up men in singles bars, is brutally murdered. The characters in "Soap" are so bedeviled by their troubles that all they can do about crime, perversion and adultery is to laugh at them.

Some of these who do cope are manifestly unreal. "The $6 Million Man" is the most egregious example. "Charlie's Angels," "Kojak," "The Hardy Boys" and most of the other successful detectives are also much too good to be true.

But the most typical survivors are those who make a joke about their way out of tight spots. Woody Allen is probably the best case in point. I love his movies, especially "Annie Hall." But the fact is that when it comes to doing anything, Alvy Singer, played by Woody Allen, comes on as an incompetent schnook, and Annie Hall, played by Diane Keaton, is a cleaned-up hippie.

Exactly what to make of all this is not clear to me. I have the distinct feeling that most Americans don't find life easy. I think that confusion and frustration - particularly with political authorities - drive them away from public affairs and into themselves. I sense that the achievement ethic is in for a rough time. It makes me slightly uneasy when the title role in the movie "Oh, God" is played by George Burns. The more so as Burns simply comes on as what he is - which is to say a borscht-circuit comic.