PROFESSOR of Government Martin Kilson played a moral trump card yesterday. In a letter to the editor, Kilson took issue with a column in which my editorial page colleague Matthew Joseph argued that Jesse Jackson lacks elective experience necessary to be president of the United States. Kilson labelled Joseph's views "neoracist."

Exchanges about Jackson's experience follow a predictable enough pattern. Now, according to this ritual, it is time for someone to argue that the real racist would spare Jackson's record the scrutiny it would receive were he white. This might trump Kilson's trump, countering his slander with another slander.

Charges of racism are blunt political instruments that shut down discussion and crush understanding. In the debate Kilson would have, the winner is whoever invokes the most stunning cloture.

Joseph makes a by-now standard case against Jackson. His view is less troubling to one favorably disposed toward Jackson's candidacy than Kilson's response. The professor's letter contributes not at all to any debate in which standards for those who would hold high elective office might be formed.

The professor takes pains to point out that Joseph's views betray "neo-racism," which "is essentially different from old-racism." In Kilson's full explanation, "neo-racism" is "a twisted-neurotic racist virus abroad among some white students--mainly white-ethnic newcomers to the middle classes--and while this neo-racism is essentially different from old-racism, it must be met and fought head-on, and the pressure must be kept on college administrations across the country."

What--any professor might ask if Kilson's letter were a student's paper--does this cryptic sentence mean? Calling neo-racism a twisted-neurotic virus, while vivid, leaves the term undefined. Its essential difference from old-racism evidently has to do with those who propound it, namely "white-ethnic newcomers to the middle class." Could the reference be to Jews (like Joseph) and Catholics (like me)?

If it's so, we're victims precisely because we're newcomers, because we have yet to be dressed-up and made presentable for the professor's polite society. The enemy Kilson wants "fought head-on" is our true, malevolent selves. And it's a reasonable, if debatable, proposition that such a fight is needed.

It's less reasonable, though, to believe that the corrective is membership in the elite Harvard establishment Professor of Government Kilson serves. Remember, the establishment is one in which Kilson both encourages political discussion in the classroom and is pleased to be a fearless thought-policeman outside it, quashing debate with allegations of "neo-racism."

IT'S WORTH considering how Kilson's academy looks up close. Consider what happened last semester when students adopted Kilson's tactics, coming up with their own code-word for racism--"racially insensitive"--and used it in pitting themselves against the Winthrop Professor of History, Stephan Thernstrom. The students, who brought their complaint before a College committee, objected to remarks Thernstrom made in Historical Studies A-25: "The Peopling of America," including characterizations of Jim Crow laws as beneficial to Blacks in diffusing white antagonism.

Any professor who rallied to Thernstrom's defense ran the risk of seeing his own reputation smeared. And any who sided with the students would break ranks with colleagues appointed for life. But the faculty is not so timid that these explanations suffice.

In the Thernstrom incident, any remark, by any professor, threatened to undermine academia's most cherished principle: the sanctity of the classroom. Any remark would make it a shade less true that there is something about what goes on in the classroom that removes it from the realm of debate--that whoever presides there is entitled to some unchallengeable prestige.

Enjoining argument over the Thernstrom incident would have implied acceptance of the agreement on which all discussion depends: that the best case should prevail. That would matter not just for Thernstrom, this time. It would establish a precedent by which to judge other professors, other times. And so Kilson had as little to say as his colleagues.

That's the price he paid so that he might now say, with full professorial sway, what in some other fellow's mouth would be small-minded. And he has the audacity to suggest that anyone who would question what he believes is in the grip of an unspeakable sickness. If the rest of us defer because of Kilson's title, or because of the stylish prefixes he uses, we'll pay a price now.