JOE is the kind of movie that makes people start to hate irrationally and want to kill each other. I guess that's no small achievement, but it doesn't cover up the fact that this low-budget American film is a mindless exploitation picture, a quasipolitical Beyond the Valley of the Dolls .

A man named Norman Wexler reportedly wrote Joe's screenplay in about a week. It shows. This movie has one of the most preposterous plots of all time, full of the kind of implausible events that made comic books so irresistibly attractive just before puberty.

Joe is a hard-hat type of guy (making $160 a week and enjoying it less) who one day hears a stranger sitting next to him at a bar confess to a murder. This stranger, you see, is a $60,000-a-year advertising exec who has just killed his wayward daughter's junkie-freak boyfriend and has no fears about admitting his crime to the first person he sees.

Rather than being shocked by the ad-man's admission, though, Joe is thrilled to death. Why? Because Joe is a working man, and working men by definition feel that all "hippies" and "niggers" should be sent to early graves. Right? (I might point out quickly here that Joe does not exactly provide fuel for Marxist-Leninist dreams of the future.)

So thrilled is Joe at hearing this casual confession of murder that he even starts up a friendship with the ad-man-a friendship that cuts across so-called class lines, a friendship the ad-man must accept for fear that Joe might otherwise turn him into the police. From this point on the film moves further into the land of the unreal; suffice it to say that its last half-hour is loaded with graphic sex, drug-popping and grand scale violence.

All of which would be quite fine, were it not for Wexler's insistence on mixing politics with the fun and games. Not real politics, but tabloid-style politics. Rabble-rousing that titillates all by playing on everyone's prejudices to no one's advantage.

Joe is depicted as a lovable Art Carney-styled nitwit, oppressed by inflation and inflamed by grand memories of that great war, WW II. You could almost love him, were his solution for his anxieties something other than shooting down long-haired youths. So, needless to say, you despise him instead. I've read that in New York freaks frequently stand up at the end of the film and yell, "I'm going to kill you, Joe!" at the screen. Swell.

Conversely, the freaks in the film come across as smack-shooting nymphomaniacs, who, in their spare time, sell phony dope to innocent high-school girls, steal people's wallets and frequent macrobiotic restaurants. In its willingness to defame all comers, Joe is marvelously democratic. While, in the end, it is the freaks who get murdered, the film's sympathies remain ambiguous. The verdict on the killers seems to be an equivocal "justifiable homocide."

IN THEIR ability to make everyone angry without taking a stand on anything, Joe's creators are performing the same kind of function that witnesses say Charles Manson had in mind when he allegedly hoped that blacks would be held responsible for the Sharon Tate murders, thereby kindling a race war. Vietnam is never directly mentioned in Joe, and plain old murder is the screenplay's raison d'etre as well as its resolution. Plain old murder not to be confused with revolution, repression or even the hard-hat-inflicted violence at a political rally on Wall Street last spring.

Joe makes you mad. It can inspire you to hate. But not the kind of hate you might feel towards our President or Marshall Ky. Rather, blind hate, as you might feel towards someone who accidentally ran his car over your dog. We are entitled to some blind hate, but Joe seeks to direct our hatred towards an entire segment of the population, a segment that presumably, like our own, defies generalization.

Hopefully most people who see Joe won't take it as the responsible political statement its creators wish it were. And, once you realize the film's failings on its most ambitious level, you can enjoy it on others. Viewed in this way, Joe is a lot of fun.

A couple of scenes are especially juicy. At one point, for reasons too amazing to explain, Joe and the ad-man participate in a freaky orgy (pronounced with a hard "g" by Joe) in the freak-infested East Village. The two hippie-haters take their share of the free sex, grass and psychedelia that abound in such haunts-and the results are, well, curious.

This same device of juxtaposing the mores of characters from wildly different socio-economic constituencies also pays off in an amusing sequence involving a dinner at Joe's house in Queens for the adman and his wife. (Joe and his spouse's social habits prove totally incomprehensible to the affluent couple-and vice versa.) Granted this device is as old as time; still, it has served movies well, from such American Depression comedies as Frank Capra's It Happened One Night to such recent sophisticated Kitsch as the current Mick Jagger Performance.

Peter Boyle's neatly turned caricature of the title character adds a great deal to the humor of Joe -as does, in a different way, the atrocious acting contributed by everyone else in the cast. Director John G. Avildsen keeps the whole thing moving, but it is unfortunate that the script's political pussy-footing and fierce determination to touch all the exploitational bases (to the extent of sacrificing all credibility) trip him up from time to time. Perhaps if screenwriter Wexler had spent, say, a month on the screenplay, Joe might have had the uncomplicated force necessary to qualify it as great trashy film-making-a category of which Russ Meyer's Beyond the Valley must remain the summer's outstanding example.