Is there really “something highly contradictory,” as Kathryn Shelton argued here on Doublethink, about a position that “advocates the regulation of marriage, but rallies behind a platform for smaller government”? Or, on the contrary, is the promotion of marriage critical to limited government, as traditionalist conservatives—among others—regularly contend?

Shelton’s argument has three main components. First, she claims that in promoting marriage as a conjugal (husband-wife) bond, the government engages in crony capitalism: “picking winners and losers in marriage may be just as detrimental to America as picking winners and losers in the economy.”

But if that’s right, is Shelton herself impermissibly picking winners and losers when she argues that “monogamous gay couples” should be treated as marriages? Why “monogamous”? Why “couples”? Why not treat polygynous, polyandrous, and polyamorous relationships as marriages? Are people inclined to multiple-partner relationships “losers” on Shelton’s view?

These questions aren’t scaremongering or slippery slope argumentation. First, in 2009 Newsweek reported that there are over 500,000 polyamorous households in America. Second, prominent scholars and LGBT activists have called for “marriage equality” for multi-partner relationships for since at least 2006. And third, most importantly, once she jettisons sexual complementarity, what principle could Shelton offer to limit civil marriage to monogamous couples?

Second, Shelton suggests that religion is to blame for our impasse: “The debate about gay marriage seems to be so delicate mainly because neither party has clearly defined the difference between holy marriage and state marriage.”

Civil law and church law are clearly two different things. But that only reinforces the point: to decide what to recognize as a marriage, the state must be clear on its own view of what marriage is, and why recognizing (and therefore regulating) such a relationship serves the public good at all. Yet Shelton never addresses these points. She simply assumes that civil marriage should take no notice of sexual embodiment, complementarity, the way sexual powers are ordered to procreation, and the ideal family structure for providing children with both mother and father. Might these be the truths grounding civil marriage?

In other words, Shelton’s view is anything but “neutral.” It is every bit as robust as the traditional conjugal view she rejects. It is only less candid about its own definition of marriage: emotional-sexual union.

Third, Shelton makes a civil libertarian argument: “Denying monogamous gay couples the rights to a host of … benefits is clearly discriminatory, arguably against existing laws forbidding discrimination by sexual orientation, and simply un-American.”

“Clearly discriminatory” and “simply un-American” are sensible claims only if one has previously defined what marriage is and which distinctions are relevant, and which irrelevant (and therefore arbitrary, unjust), for a sound marriage policy. We are all in countless bonds that get no legal recognition, no legal benefits, and no one thinks this discriminatory—because no one thinks they are marriages.

This is why her appeal to a civil rights analogy—“Allowing heterosexual couples to ‘win’ and homosexual couples to ‘lose’ is as prejudiced as the Jim Crow laws”—simply begs the question. As has been explained time and time again, race is utterly irrelevant to what marriage is. But the precise disagreement in our current marriage debates is whether sexual complementarity—because of the type of bodily union it makes possible through conjugal acts—is relevant to marriage. Shelton clearly thinks that it is not. But one has to argue for, not simply assume, one’s conclusion.

Putting these threads together, Shelton reaches her conclusion that marriage supporters “are essentially advocating for the Church and the State to be one and the same. They are fighting for bigger government and cronyism in marriage, although they claim to want more individual freedom and personal liberties elsewhere. The inherent contradiction is astounding.”

But there is no contradiction here once one considers the actual arguments advanced by Shelton’s opponents and left unaddressed by Shelton herself.

In our article in the Harvard Journal of Law and Public Policy “What is Marriage?” my co-authors and I have argued philosophically that marriage by its very nature is a union of a man and a woman. (Later this month Encounter Books will release an expanded and enhanced version of the argument.)

At the heart of the argument is an understanding that natural (not supernatural, sacramental, or religious) marriage is a pre-political institution springing from human nature itself. Prior to any governmental diktats, marriage has its own essential structure and norms and serves its own ends. Our marriage law should reflect the truth about what marriage is.

Government promotes the institution of marriage because of the ways in which marriage serves the political common good. Marriage brings together a man and woman as husband and wife to be father and mother to any children their union produces. As the sexual acts that unite a man and a woman are the same acts that bring forth new life, the state has an interest in channeling sexual desire toward a stable relationship: marriage. As children have a right to, and tend to do best when, reared by their mother and father, the state protects child welfare by encouraging adults to make commitments to each other and their children by living according to the norms of marriage. So while the state disregards our ordinary friendships and extended family relationships, it rightly regulates and promotes marriage and marital childbearing and rearing.

But any attempt by government to redefine or recreate this pre-political association, to obscure its essential features and reshape it to serve external social ends, is a prime example of state tyranny—something liberty-loving, limited-government supporters should resolutely resist.

Recognizing same-sex relationships as marriages would also weaken marriage as a social institution and harm the common good. It would redefine marriage as essentially an emotional bond, rendering marital norms—monogamy, sexual exclusivity, and permanence—arbitrary. The public message it would send would deny the importance of the complementarity of mothers and fathers to the parenting enterprise, and would result in poorer outcomes for many children. As a result, the state’s welfare and judicial activities would expand, and religious and other civil liberties would be threatened.

In a series of articles for Public Discourse, the online journal that I edit, the Austrian-school economist Dr. Jennifer Roback Morse has developed the argument of her first book, Love and Economics: Why the Laissez-Faire Family Doesn’t Work, to address additional libertarian concerns. She argues that “Privatizing Marriage Is Impossible,” that “Privatizing Marriage Will Expand the Role of the State,” and that “Privatizing Marriage Is Unjust to Children.”

Shelton’s claims about liberty, crony (marital) capitalism, and limited government make sense only if one thinks the family is just like any other market activity. But sex makes highly needy, totally dependent, non-autonomous market actors: children. Promoting marriage as a conjugal union between a man and a woman is the least restrictive way a government can help ensure that children are reared to become healthy, upright, economically productive and responsible citizens that make limited government possible.

Ryan T. Anderson is the William E. Simon Fellow at the Heritage Foundation and the Editor of Public Discourse. With Sherif Girgis and Robert P. George he is author of What is Marriage?: Man and Woman: A Defense to be released by Encounter Books later this month.