KATHERINE MACKINNON is a woman with a mission. Like a modern-day Carry Nation, she intends to shut down America's dens of depravity MacKinnon's targets, however, are not the Piccadilly Filly or the Boathouse, but Nini's Corner and Out of Town News Katherine MacKinnon wants to make the world safe for America's women by closing down shops that sell smut.

MacKinnon, a University of Minnesota law professor and a recent speaker at the Law School, co-sponsored a Minneapolis municipal ordinance with feminist writer Andrea Dworkin that defines pornography as a violation of a woman's civil rights. This bill, which was vetoed by the Mayor, would have allowed anyone to sue the creators and distributors of pornography for damages, effectively putting them out of business.

The Dworkin-MacKinnon ordinance is part of a recent trend among feminists, who are critical of pornography and its effects on society's perception of women. Feminists like Dworkin contend that the portrayal of women as submissive sexual objects promotes a degrading attitude toward women that in turn leads to sexual discrimination, harassment, abuse, and rape. They have written articles, staged marches, and given speeches advocating the banning of obscene material because of its damaging effects on women.

And on May 1 the city of Indianapolis, with the aid of anti-obscenity activists from Minneapolis, drafted and passed an ordinance similar to MacKinnon and Dworkin's. It was immediately stayed by a Federal District Court judge, and further arguments on the ordinance's constitutionality are pending.

But the contentions of these activists rest upon two shaky assumptions. The first is that pornography directly fosters a sexist or aggressive attitude towards women. Studies have attempted to demonstrate this, but the most they have been able to show is a correlation between these attitudes and pornography. Some have pointed out that the increasing availability of pornography has coincided, with a large increase in sexual assaults. But most experts believe that rapes were grossly under-reported in the past, so the real increase in the number of assaults can only be guessed at. Furthermore, the role of pornography is not well understood; it' may act as a safety valve as well as a model for sexual aggression. Blaming rape on the prevalence of pornography is simplistic, and it may not be borne out by the facts.

The second assumption is that some workable definition of pornography can be found. The courts have had enormous difficulty trying to define what is and is not pornographic. In order to meet the criterion of specificity that the Supreme Court demands of a statute, the MacKinnon-Dworkin bill committed the sin of ridiculousness. Under the proposed ordinance, any work that portrays women "who are tied up or cut up or mutilated or bruised or physically hurt" or that shows women as "filthy or inferior" qualifies as pornography. Out goes A Clockwork Orange, Gone with the Wind, and almost every action film ever made. When MacKinnon was asked whether the bill was overly broad, she replied. "Tell us how to make it better." This statement effectively sums up the problem of subjectivity. Smut is in the eye of the beholder; it is difficult, if not impossible, to set an objective standard.

EVEN SETTING ASIDE these objections, however, MacKinnon's proposal still founders on several key points. Pornography may contribute to an attitude conducive to sexual harassment and rape, but the same has been about suggestive advertising. And why limit a campaign against violence to that committed against women? Studies have documented the link between violence on television and violent behavior; The A-Team encourages more violence than Hustler and Screw combined.

It is preposterous to hold creators responsible for the indirect effects of their speech or publications on certain dangerously impressionable members of society. Ought President Reagan to be able to sue Jodie Foster and Martin Scorsese because they inspired John Hinckley? One is reminded of the trial in Florida a few years ago, in which a juvenile delinquent claimed that his crimes stemmed from a Kojak addiction.

Dworkin and MacKinnon couch their discussion in terms of establishing equality between the sexes, but their real complaint is that women don't receive equal respect. Pornography is a double insult; it denigrates women and has fun doing it. But turning to the law to endorse a stiff-necked Victorian worship of womanhood's worth is hardly an answer. It implies that there is a moral right to extract respect from the disrespectful. A widespread perception of feminine inferiority infringes on the real equality of the sexes, but this perception must be changed by conversion, not coercion.

IT TOOK THE WOMEN'S movement 20 years to quash the turn-of-the-century stereotype of the suffragette as a humorless shrew. Foolish efforts to raise the status of women by fig-leaFing the media will ressurect this long-dead stereotype. Feminism fought a long battle to be taken seriously; feminists like MacKinnon and Dworkin are only inviting the kind of derision they want to avoid.

More important, when feminism appropriates the moral arrogance of the New Right, it starts to become indistinguishable from its opposite. There is no small irony in the fact that the MacKinnon-Dworkin bill would not have made it to the Mayor's desk without the support of two-right-wing city councilmen who saw the ordinance merely as a means for cleaning up the neighborhoods. Feminism began as a crusade for the dignity of half our nation, but if feminists like Mackinnon and Dworkin continue to focus on the wrong issues, it may degenerate into an hysterical ideology of sexual righteousness.