Marriage is something easy to take for granted. But America has been undermining it. The no-fault divorce revolution, in particular, harmed marriage deeply, by changing it to allow either party to just walk away from it.

Same-sex marriage carries the process of undermining marriage further. Marriage, traditionally understood to be the union of one man and one woman that is the basis of family life, is again re-formed according to contemporary preferences.

Most people recognize that marriage has certain characteristics that are inherent in it and should not be subject to human preferences. For example, most of us think that marriage should be between two people, not three or more. Why? Because we think that the nature of marriage requires that the people involved really commit the whole of themselves to one other person. No matter how much and how sincerely three people may love each other, most of us think they should not be able to have a married threesome.

Likewise, another essential – not just optional – feature of marriage is gender complementarity, because men and women each bring something different to the most important function marriage serves: bringing new children into existence. The state has an interest in fostering marriage as the privileged place for raising children, so that they have both fathers and mothers. In the case of homosexuals, there is simply no interest the state has in the private, "intimate" relationship of two people.

Because the opponents of the state marriage amendment know that they will lose an election focused on the question of same-sex marriage, they have tried to invent another issue. They claim that the second part of the amendment will deprive people of various benefits.

But the authors of this amendment, from the very beginning have said that the amendment will have no impact on such benefits. The ones making that argument are the ones opposing the amendment, whose self-interest is to make it mean something less popular. Who should know more about what the amendment means?

(What is the purpose of the second part of the amendment? Simple: it prevents not only same-sex marriage, but also unions identical to same-sex marriage, but with merely a different name, and other unions virtually identical to same-sex marriage, with only minor differences in order to evade the prohibition. None of this touches on the right of people – homosexual or heterosexual – to various benefits, as long as the benefits are not based on a marriage-like legal status.)

Marriage is not something we can keep manipulating without damaging it. We live in a society where marriage is already seriously weakened. Rather than making it even more plastic or "adjusted to human preferences" than it is, we should be trying to restore its solid core and its stability. That's what the amendment does, and why we should vote for it.

Wolfe is a professor in the Political Science Department and a member of the Wisconsin Coalition for Traditional Marriage's advisory council.