Although we know from biological science the equal contributions that both parents make to the genetic identity of a child, it is still true to say that the mother is the “more natural” parent, the parent by birth. A woman can give up a child for adoption, or, thanks to modern reproductive technologies, can even bear a child not genetically her own. But there is no way to deny out of whose body the new life sprung, whose substance it fed on, who labored to produce it, who wondrously bore it forth. The father’s role in all this is minuscule and invisible, in contrast to the mother, there is no naturally manifest way to demonstrate his responsibility.
The father is thus a parent more by choice and agreement than by nature (and not only because he cannot know with absolute certainty that the woman’s child is indeed his own). One can thus explain the giving of the paternal surname if the following way: the father symbolically announces “his choice” that the child is his, fully and freely accepting responsibility for its conception and, more importantly, for its protection and support, and answering in advance the vital question: Who’s my dad?
The husband who gives his name to his bride in marriage is thus not just keeping his own; he is owning up to what it means to have been given a family and a family name by his own father. He is living out his destiny to be a father by saying yes to it in advance. And the wife does not so much surrender her name as accept the gift of his, given and received as a pledge of (among other things) loyal and responsible fatherhood for her children. A woman who reuses this gift is, whether she knows it or not, refusing the promised devotion or, worse, expressing her suspicions about her groom’s trustworthiness as a husband and prospective father.
Patrilineal surnames are, in truth, less a sign of paternal prerogative than of paternal duty and commitment, reinforced psychologically by gratifying the father’s vanity in the perpetuation of his name and by offering this nominal incentive to fulfill his obligation to mother and child. This naming custom enables the father to become explicitly the parent-by-choice that he, more than the mother, must necessarily be. Fathers who will not own up to their paternity, who will not “legitimate” their offspring, and who will not name themselves responsible for childrearing by giving their children their name are not real fathers at all, and their children suffer. The former stigmatization of bastardy was, in truth, meant to protect women and children from such irresponsible behavior.
Leon R. Kass – Leading a Worthy Life: Finding Meaning in Modern Times p.132