I live in New Jersey. I don't know how to say that without sounding like I'm making either a confession or an appeal for pity. But the fact of the matter is that I like New Jersey, and have liked it ever since I moved there from Michigan four years ago. Of course, it has a state government, but then Michigan had one too, so I can't really say I'm worse off in that respect.

New Jersey is governed in part by a body that one wag has called a "dirty old legislature." Two years ago the lawmakers reduced the sexual age of consent to 13, apparently on grounds that anyone old enough to pay adult fare at the movie should have the right to form a liaison with anyone else who may be lurking there. For once the good and patient people of New Jersey refused to play the role of consenting adults, and the law was hastily repealed.

But the state, irrepressibly, is not moving to institute what it calls "sex education." A number of school districts in other sta tes already offer (or impose) such courses, but the idea isn't going over too well with us Jerseyites. Nor should it.

The whole idea of "sex education" as we know it is fraudulent. It is based on the assumption that good information leads to good behavior. To call this notion a half-truth would be to flatter it. Ever since Hugh Hefner brought mammography to the millions a quarter-century ago, we have been deluged with "openness," "candor" and the like. Has the increase in accessibility brought a decline in premarital pregnancies, veneral disease and other sexual disorders?

On the contrary. Any fair-minded person must admit that by every objective index we are doing a lot worse now than we were back when sex was surrounded by taboos, and had to be learned about in the gutter.

That is not, I hasten to add, an argument for taboo and gutter. It is simply a reminder of the obvious, that knowing the facts is of only limited value. Information is just one part of education. Real sex education has to be a form of moral education: if you want to get people to behave differently, you have to present them with moral imperatives. A good sex education the kind you should have gotten from your parents, includes such injunctions as, "Wait until you're married." People who reject that counsel are in an awkward position to argue against premarital pregnancy.

That's the trouble with sex education of the kind we're now being urged to adopt. The people who want us to have it are the very sort of people I'd rather not have administer it. They want to do away with conventional wisdom, but they also want to keep the benefits that the conventional wisdom produced and that modern enlightenment can't.

The problem is that you can never derive a conclusion in the imperative from premises in the indicative: as the philosophers say, "is" doesn't yield "ought." If you want to prevent the bad consequences of sex, you have to do what liberal folk hate to do: utter stern nagative commands. "Thou shalt not."

The irony is that liberals are making sex ugly, despite their frequent talk of developing "positive" and "healthy" attitudes toward it. Take away the support of morality, grounded in self-respect and self-restraint, with all the lovely reinforcement of courtship rites, and the only way to discourage misbehavior is to dwell on its nastiest effects. When chastity was implicit in our very manners, people needed only a little encouragement to be chaste. Now we spend an inordinate amount of time thinking up reasons and inventing motives for a virtue we once could take for granted.

Liberal-style sex education, by omitting the moral dimension, may inadvertently act to condone what it seeks to prevent. Treating sexual intimacy in the spirit of the clinic, it is likely to weaken not only the morality but the mystery of two sexes. The very reticence it seeks to overcome has its own place in sexual relations, and has helped keep people virtuous even when they couldn't explain why. Don Giovanni may do more good than Kinsey. At least that's the way I think most New Jerseyites feel about it.