The Alexandria school board's resolution in support of a proposed "teen clinic" didn't mention the dispensing of contraceptives and birth-control devices. It didn't have to. Everybody knew what the controversy over the clinic -- to be located either in or near the city's only public high school -- was about.

"The emotional, social and fiscal costs of teen-age pregnancy are overwhelming," explained Judy Seltz, the school board member who introduced the resolution. "Our kids need the clinic."

Seltz exhibited no awareness that her two-part formulation might have constituted a non sequitur.

Surely everybody agrees that teen-age pregnancy -- and teen-age childbearing -- is costly. Surely no one disputes that Alexandria's high school students could use a health clinic. It is the doubtful relationship between the two that is at the center of the controversy.

Will the establishment of the clinic (which still must be approved by the city council) make a serious dent in the problem of teen-age pregnancy and childbearing?

Try putting the question another way: are Alexandria youngsters getting pregnant because they don't know about, or cannot get, birth-control devices? The six members of the school board who voted in favor of the resolution obviously believe they are. The two who voted "no" and the one who abstained have their doubts.

The doubts are well-founded. T. C. Williams has one of the most extensive sex-education curricula in the state. Its students have access to two clinics -- one run by the city Health Department, the other by a Methodist church -- that dispense birth-control information and devices. But Northern Virginia still has the highest rate of teen-age pregnancy in the state.

There is also the question of whether the school board's endorsement of the clinic amounts to an endorsement of adolescent sexual activity. The supporters obviously don't think they are sending mixed signals. But are they?

Suppose the problem at issue was "the emotional, social and fiscal costs" of teen-age drug abuse, and the proposed remedy was a clinic designed to help young drug abusers avoid the awful consequences of their behavior -- perhaps by teaching them fine points of safe dosages, clean needles and first-aid for cases of accidental overdose. Everybody might agree that drug abuse was a serious problem. But how many would conclude that our kids need such a clinic"? Wouldn't we be afraid that such a drug-education program might increase, rather than decrease, the incidence of drug abuse?

I know, I know. Sex and drugs are different; one is natural and at least tacitly legal, while the other is artificial and unlawful. The point is the psychology involved. Why would anyone expect the establishment of a clinic to curtail one form of dangerous activity and not the other?

But isn't the alternative to the "teen clinic" an ineffectual "just say no" campaign? While I believe that our schools ought to be helping youngsters to say "no" to adolescent sex, I grant that moral preachments won't do the job.

What will? The answer begins with getting the question right. It is no coincidence that the highest pregnancy rates are among those youngsters who have the greatest doubts about their futures. The question is not how to teach young people to avoid the consequences of premature sex but to give them a reason for doing so.

Carol Randolph, the former TV host and now newspaper columnist had it right the other day.

"After years of doing television shows on the topic of teen pregnancy," she wrote in the Washington Times, "I have come to the conclusion that young women who believe they can make something of their lives, {that} they can achieve certain goals, haven't got the time or the inclination to become pregnant."

Just so. If Alexandria really wants to help its teen-agers -- boys as well as girls -- it ought to look for ways to steer them into worthwhile careers, to let them know that they have it in their power, with help from the wider community, to "make something of their lives."

Contraceptive ignorance isn't the problem; despair is. Replace that despair with a well-founded confidence in the future, and the teen pregnancy epidemic will take care of itself.