SOCIAL SCIENTISTS, legislators, educators and a lot of parents will be watching the dairy state next year. It's not milk price supports or the Green Bay Packers that provoke interest but a new law -- the first of its kind in the nation -- just adopted in Madison. The statute imposes financial responsibility for infants born to unmarried minors on the baby's grandparents. Its objective is not only to cut down on teen-age pregnancies by involving the teen-agers' parents, but also to reduce the burden on the state's welfare rolls. Sixty percent of all teen-age mothers nationwide require aid. The question is whether it will work, since if it does there is little doubt that other states will want to take similar action.

Out-of-wedlock births to teen-agers are devastating not only to the girls who bear children too soon, before completing their education or learning a skill or developing the emotional maturity and stability required of a parent. We know also that children born under these circumstances start out in life with an extraordinary number of strikes against them, raising the probability that they, too, will find it very hard to move out of poverty later in life.

How does society step in to discourage premarital pregnancy when its traditional moral code requiring abstinence seems to be in abeyance? Increasingly it seems that parents have left the answer to this question and their responsibility in relation to it to the schools and social service organizations. The Wisconsin law is designed to remind potential grandparents that this change of attitude in which so many of them acquiesce, albeit uneasily, has consequences and that they must accept responsibility which is theirs. Not such a bad idea.

We expect that the law will have an impact on families with any ability at all to make support payments. This is likely to be specially true of boys and their parents who, in most cases, have borne little of the burden so far. Welfare families pose quite another problem, and the Wisconsin regulations for applying the new law in these cases are still being written. The law itself is a temporary one that must be reconsidered in 1989. But if it produces results, the primary beneficiaries will not be the taxpayers or even the dependent infants, but those teen-agers who postpone parenthood until they've had their full share of childhood themselves.