The question of same-sex marriage is usually approached as though the state awarded couples the benefits of marriage by right of their mutual affection – and shouldn’t all affections be included as a matter of justice?
But the purpose of state-sponsored marriage is to protect and nurture children, not to dignify every sort of fond feeling. Same-sex romantic partnerships are, by their nature, unrelated to the production and raising of children and so are not the kind of friendships suitable for marriage.
In contrast, sexual love between a man and a woman is fundamentally ordered to the procreation of children. Children are the expected natural outcome of the relationship, which forms, not coincidentally, the ideal arrangement for their care and raising.
The statistics are beyond dispute at this point: Children do best socially, emotionally, academically and materially if they are raised and nurtured by their own parents in a single household. Marriage between a man and a woman is the best incubator of future citizens, so governments have always tried to promote and fortify the institution.
Others may “pinch-hit” in the raising of children when the natural family structure has collapsed. However, an intact natural family is statistically preferable, and society recognizes this fact through the rights and benefits conferred by state marriage.