Movie journalists agree it's a trend: After a long spate of whimsy and fantasy, films are tackling serious matters again. Among current releases, ''Daniel'' deals with left-wing politics through the eyes of a man whose parents were executed for espionage. ''Merry Christmas, Mr. Lawrence'' analyzes East-West relations via a World War II prison-camp story.
This fall, judging from advance reports, more than a half-dozen new pictures will have topical subject matter, and at least some will take politically outspoken stances. ''Hanna K.,'' by the director of ''Missing'' and ''Z,'' examines Israeli fairness regarding the Palestinian cause. ''Silkwood,'' directed by Mike Nichols, is named after an actual woman who alleged abuses at a nuclear processing plant and then died under unusual circumstances.
The main characters of ''Under Fire,'' played by Nick Nolte and Gene Hackman, are journalists of the 1970s who get involved in the Nicaraguan civil war. Hackman stars again in ''Last River to Cross,'' about an American searching Vietnam for his missing-in-action son. Vietnam is also the focus of ''Streamers, '' about tensions among men awaiting combat, and ''Boat People,'' about a Japanese photographer who finds corruption raging three years after the fall of the Thieu regime.
''Deal of the Century'' reportedly takes a gallows-humor approach to the arms race. ''The Final Option'' - expected to be the most conservatively slanted of the new films - is described as a thriller about a Soviet-duped antinuclear group that besieges an embassy.
All these pictures come on the heels of a boom in historical movies as varied as ''The Return of Martin Guerre,'' ''La Nuit de Varennes,'' and even the comical ''Zelig.'' Clearly there is a tendency away from the frivolity of ''E.T.'' and the ''Star Wars'' epics and back toward the real world.
Why? For several reasons, I think. One is the success (in both dollars and prestige) of ''Gandhi,'' which proved that history and politics won't scare today's audiences away if cannily treated. The reception of other politically charged pictures - from ''The China Syndrome'' to ''WarGames'' and ''The Deer Hunter'' - has given further encouragement to producers and exhibitors alike.
The filmmakers may also be taking a cue from television, which - with its quick work habits and tight schedules - can plunge into topical material at will. And the overall level of feature-film production has been soaring in Hollywood lately. This means more pictures of all types - and more opportunities for risky projects to make their way from drawing board to sound stage.
The movie community could be making a bid for prestige, too, after its recent romance with very frivolous fare. Filmmakers like having an impact through their work, and the chance of influencing public opinion has tempted more than a few. Some of the forthcoming releases could well succeed on this level. According to a New York Times report, ''The Final Option'' has won praise from conservative politicians after advance screenings in Washington, while ''Under Fire'' has been lauded by a congressman who wants to prohibit the introduction of United States combat troops into Central America without clear congressional action.
The biggest reason for the new seriousness, though, could be just another swing of the old pendulum. Even moguls must long for a change after endless movies about space-borne heroes and kooky teen-agers. Evidently the change is here, and we're in for some provocative fare. That's good news. But it may not last long, especially if the box office doesn't swell - soon - with Hollywood's only constant: money.
Some of the recent comedies have declared war on the middle class. The result , predictably, is a draw.
Vacation is presented by National Lampoon, the same magazine that gave us ''Animal House'' a few seasons ago. And my, how the young Turks have mellowed. ''Vacation'' earns its R rating with a few dirty words and sex jokes. But compared with the boorishness of ''Animal House,'' it's like cream cheese after Limburger.
Chevy Chase plays a Chicago dad who loads his brood into the station wagon and heads for a ''fun park'' in California. The going is rough. The luggage won't stay on top, the hubcaps get stolen, the gas-station men are crooks, the kids are bored, and Aunt Edna seems to have expired in the back seat. But our hero won't quit, and even the final indignity - his destination is closed for repairs - finds him as resourceful as he is desperate.
It's a funny idea: the vacation as ordeal, the ''good time'' as a trial by highway, credit card, and insufferable in-law. Chase makes a good hero, smooth and bumbling at the same time, and the supporting cast is mostly excellent. But the gags are often obvious, and most of the vulgarity seems tacked on, like a sop to current fashion that even the filmmakers don't care much about.
And who's responsible for all the racist attitudes? Black people make two appearances: in a ghetto scene, where they're seen as thieves and prostitutes, and near the end, when a black man is forced at gunpoint to behave like a dog. Even if these supposedly comic scenes are necessary, which I doubt, where are some positive and dignified black portrayals to offset them - and show some good faith on the part of the filmmakers?
Ideally, perhaps, jokes aimed at blacks would seem no more or less offensive than those aimed at whites. But we certainly haven't reached that stage of racial equanimity, especially in Hollywood, where blacks are shockingly underrepresented in virtually all positions and productions. Next time, National Lampoon, how about roasting racism off the screen instead of treating it like an old pal?
By contrast, Mr. Mom tries so hard to be enlightened that it almost succeeds. Michael Keaton plays a laid-off engineer who minds the house while his wife (Terri Garr) makes a splash in the advertising biz.
The screenplay is even-handed to a fault - he finds how hard it is to run a household, she meets the pressures of the business world, and both learn to value their marriage more than ever. But the situations are stupid more often than funny, and the plot soon falls back on old canards about the suburban and corporate scenes being sexual playgrounds. Surely the movies could offer us a more original vision than this, even in a warm-weather farce.