Reflections on the Public Purpose of Marriage

My intention in writing this article is to explore long-standing legal principles of marriage and their scriptural endorsement as a means of delineating the over-arching public reason for marriage.

I will also provide examples that demonstrate how this public reason is being undermined by the re-definition of marriage. The repeated and inevitable result is that the mere intention of a couple to parent together is overriding the child’s inalienable right to its native identity and biological heritage.


Public Reason

Public reason is the ground of modern public policy. It requires that “rules can only be imposed rightly on persons when the rules can be justified by appeal to ideas or arguments that those persons, at some level of idealization, endorse or accept.”1

This concept owes much to the philosophy of John Rawls, Jürgen Habermas, and Gerald Gaus, who developed their ideas from previous work by Hobbes, Kant, and Rousseau.

While public reason doesn’t preclude wide-ranging and divergent personal reasoning (e.g. for entering marriage), in his book, Political Liberalism, John Rawls explains the necessity for those who engage in political debate to: “give properly public reasons to support the principle and policies [the] comprehensive doctrine is said to support.”2

Without public reason undergirding policy, society becomes unfair, privileging certain moral constituencies and private interests above others.

It is with reference to the public reason for marriage that the noted 18th century jurist Sir William Blackstone stated in ‘Commentaries on the Laws of England’:

The main end and design of marriage therefore being to ascertain and fix upon some certain person, to whom the care, the protection, the maintenance, and the education of the children should belong; this end is undoubtedly better answered by legitimating all issue born after wedlock, than by legitimating all issue of the same parties, even born before wedlock, so as wedlock afterwards ensues…because of the very great uncertainty there will generally be, in the proof that the issue was really begotten by the same man; whereas, by confining the proof to the birth, and not to the begetting, our law has rendered it perfectly certain, what child is legitimate, and who is to take care of the child.”3

This principle, known as the presumption of legitimacy through marriage, is a fundamental building-block of intergenerational kinship. Without this, lines of family descent and affinity would require constant legal interventions and intrusions upon privacy (e.g. DNA testing by default) fro legal recognition.

Nevertheless, the marital presumption of legitimacy (that through marriage the husband is presumed to be the father of his wife’s children) can still be overturned (i.e. is rebuttable) by clear and convincing biological evidence that someone else is the child’s father.

In other words, if biology (DNA evidence) contradicts the presumption, then biology wins.

So, the public reason for marriage is to fix spouses with joint responsibility for the care, the protection, the maintenance of children; but without undue intrusion upon family privacy. Nevertheless, in so doing, marriage law must continue to uphold (instead of intentionally overturning) the primacy of biological kinship.


Kinship in scripture and Christian tradition

This principle of kinship is evident in Genesis 2:23, 24. Adam’s declaration of kinship with Eve is central to the archetypal God-given marriage bond to which Christ Himself harks back. The impetus behind this archetype is the divine formation and differentiation of female Eve from male Adam’s own substance.

Beyond its statement of likeness, “flesh of my flesh and bone of my bones” is a description of Eve’s God-given derivation from Adam (which Paul explains to be mutualised in 1 Cor. 11:8 – 11).

So, in ‘Of the Good of Marriage’, St. Augustine highlights this native kinship as a God-given public good of marriage: “God willed to create all men out of one, in order that they might be held in their society not only by likeness of kind (generis), but also by bond of kindred (cognationis vinculo tenerentu)”.4 

Christ confirms this God-given Genesis archetype is part of the unrevoked divine ordering of intergenerational kinship: “That is why a man leaves his father and mother and is united to his wife, and they become one flesh.” (Matt. 19:5; Eph. 5:31)

It is not sexual activity, but this bond of kindred, which God initiated through the creation of Eve that remedies through family kinship and human society the concern that God Himself mentions: “It is not good that man should be alone.” (Gen. 2:18)

In Gen. 29:14, Laban uses similar phrasing to confirm the importance of his biological kinship to Jacob, his nephew: “Surely you are my bone and my flesh.”


Key historical evidence corroborating this public reason for marriage

In Roman times, as the public reason for marriage, the presumption of legitimacy was upheld by the maxim: “Pater est quem nuptiæ demonstrant” (“he is the father whom the marriage points out”)5

In the wake of the widespread destitution that resulted from Henry VIII’s Dissolution of the Monasteries (1536), his Vicar-general, Thomas Cromwell, not only implemented the Tudor Poor Laws, but also issued a mandate (in 1538) for parish priests to maintain parish registers of marriages, baptisms and funerals.6

Before the advent of General Register Office, the parish register of marriages provided presumptive evidence for fixing joint parental responsibility. This secured the care of all children of married parents. Nevertheless, this presumption could still be overturned by convincing contrary evidence that the husband was not the actual father.

Part of that parental responsibility relates to inheritance. Again, Blackstone, in describing lifelong contingency for a married couple to have offspring, wrote:

“A possibility of issue is always supposed to exist, in law, unless extinguished by the death of the parties; even though the donees be each of them an hundred years old.”7

So, the lifelong contingency for offspring (based on validly applying the prima facie possibility of issue) and the required intergenerational perdurance of kinship relations provides the objective basis for the opposite-sex requirement of marriage.


How does marriage’s contingency for offspring relate to childless couples?

This ‘possibility of issue’ is a prima facie [i.e. at first sight] contingency that does not prevent infertile straight couples from marrying. At first sight, opposite-sex couples are presumed to warrant this contingency.

Despite this objective prima facie requirement, the marriages of infertile straight couples have been cited as a comparator to demonstrate that the denying marriage to same-sex couples (whose relationship is constitutively incapable of procreation) constitutes homophobic discrimination.

In fact, the constitutive incapacity to procreate is not infertility. The World Health Organisation objectively describes the latter as “a disease of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse.”8

Furthermore, the possibility of issue is also the objective reason that, in Schalke and Kopf v Austria (2011), the European Court of Human Rights upheld the ruling of the Austrian Constitutional Court and rejected the same-sex couple’s claim against the Austrian state for not legislating for same-sex marriage:

“Neither the principle of equality set forth in the Austrian Federal Constitution nor the European Convention on Human Rights (as evidenced by “men and women” in Article 12) require that the concept of marriage as being geared to the fundamental possibility of parenthood should be extended to relationships of a different kind. (…) “The fact that same-sex relationships fall within the concept of private life and as such enjoy the protection of Article 8 of the ECHR – which also prohibits discrimination on non-objective grounds (Article 14 of the ECHR) – does not give rise to an obligation to change the law of marriage.”9

From time immemorial, the use of subsidiary routes to parenthood (such as adoption) has meant that there is no similar impetus for childless straight couples to gender-neutralise the marital presumption of legitimacy, or campaign for triple-parenting laws.

What’s important is that any subsidiary routes to parenthood do not overturn the child’s inalienable right to its biological kin.


Public reason - The law’s duty to promote perdurant (biological) kinship ties

While there are other subsidiary forms of kinship (e.g. adoption), the settled and stable character of primary ‘blood’ relations is critical to the intergenerational permanence of kinship and ancestry.

Boston Law School Professor Scott T. Fitzgibbon highlights this in this 2015 paper, ‘The Law's Duty to Promote the Kinship System’ 10:

“Note the socially settled and stable character of kinship roles. They are not bargained out anew in each iteration. Your belief as to who is your sister is the same as that of your parents, and of all your relatives, on that point. The roles are slow to change. The meaning and moral content of parenthood, grandparenthood, and other kinship offices alter little from generation to generation. These features-perdurance of membership, stability of role-are basic to the achievement of kinship goods.”

This intergenerational requirement for perdurance of membership explains why family kinship is best founded upon types of relationships for which the shared social meaning is immutably defined.

As FitzGibbon further explains:

“You will always be a son or daughter of your parents. Aspirationally, and in many instances actually, your father will always be the husband of your mother. Your grandparents and cousins and so on will be such so long as you and they live. From most such roles, no one can resign. The duties and responsibilities of such roles cannot be abjured without a hit to reputation and even to self-esteem. These roles last even beyond the grave; they will be mentioned in your obituary and on your gravestone.”

Professor Fitzgibbon highlights the danger of legal re-definition of kinship roles and relations, by contrasting the permanence of such perdurant relations with the transitory nature of contractually re-defined kinship:

“Contrast the instability, inconstancy, and dis-integration introduced when family membership is based upon the slippery surface of contract. Contracts may be created at any time and with almost any person. The duties they create may be assigned to others. They may last for but short periods; they may be discharged; they may be voided by change in circumstances or mistake. They may be rescinded by consent. They may be-they usually are-mutually independent: the purposes of one agreement may be divergent from those of others. A party to a contract may be excused if the other party has committed a misrepresentation.”

So, according primacy to biological kinship is an essential bulwark against children being made vulnerable to these vagaries of contractually defined and re-defined kinship forms.


Biological kinship undermined - ‘Real world’ examples

  • The matter of Q.M. vs. B.C. (2014) 11

This case provides a modern-day example of how marriage law has been leveraged in an attempt to override the primacy of a child’s native kinship. This threatens the child’s inalienable right to its identity and ancestry.

The court said: “Here, the respondents seek to rely on the presumption of legitimacy to establish Ms. S. as J.C.’s second mother, effectively extinguishing J.C.’s right to have a father. Ms. C.’s credible and uncontradicted testimony at the hearing was that she did not have sexual relations with any man other than Mr. M. during the period of J.C.’s conception, and that Mr. M. is J.C.’s father.  Thus, there is no dispute that Ms. S. is not, and could not possibly be, the second parent of this child.  Moreover, Ms. S. reconciled with Ms. C. after Ms. C. discovered she was pregnant, and presumably after she had been told that the child was fathered by Mr. M.”

Ms. C was seeking to extinguish her child’s inalienable right to the native paternal component of its identity (in favour of her former spouse) by insisting that the marital presumption of legitimacy should be gender-neutral.

the plaintiff framed her attempt to erase her daughter’s male parentage as a right of marriage equality. The judge said as much:

“Ms. C. argues that the rights of “non-biological parents” are entitled to the same constitutional protections afforded biological parents and suggests that the Marriage Equality Act requires that all spouses be treated in a completely gender-neutral manner.  It is this court’s view that the Marriage Equality Act does not require the court to ignore the obvious biological differences between husbands and wives.  For instance, as explained above, Domestic Relations Law § 73 can be easily applied to same-sex female married couples, but not to same-sex male couples, neither of whom are able to bear a child.  In the same vein, neither spouse in a same-sex female couple can father a child.  Thus, while the language of Domestic Relations Law § 10–a requires same-sex married couples to be treated the same as all other married couples, it does not preclude differentiation based on essential biology.”

In fact, such attempts to supplant native parenthood with intentional parenthood are not anomalous. There are numerous other case law examples, including those listed below:

Each case points to the ‘lived experience’ of a child’s “inalienable right to retain his true and genuine personal, legal and family identity” being legally undermined by the demand for marriage to be gender-neutralised in the name of equality.

Dr. Jennifer Roeback Morse, founder of the Ruth Institute, has explained how California’s three-parent law directly resulted from a case (In re: M.C.), which is similar to Q.M. vs B.C. Thereby, California’s social services sought to disestablish the known father’s relationship with her child in favour of her former same-sex spouse 12:

“If all same-sex couples were completely and permanently committed to ensuring that their child would never have a relationship with his or her other biological parent, then there would be no particular drive for same-sex parenting to lead to triple-parenting. But this is obviously a very strong condition. Some female couples will want their children to have an ongoing relationship with their father. Some fathers will want a relationship with their children. Hence, we can see that through situations such as these, normalizing same-sex parenting creates momentum for triple-parenting.”

“Only some known donor fathers will be fathers on the exact terms desired by the two women. Other fathers will desire something different, either more or less involvement than the women want. We cannot count on private agreements among the parties to solve all problems and manage all disputes. A subset of these cases is going to end up being settled by the family courts. Therefore, not only does same-sex parenting create an impetus to triple-parenting, it creates an impetus for state involvement in the ongoing management of these complex relationships.”

The International Lesbian and Gay Association provided the following as an amendment to the Proposed European Convention on Family Status 13.

Parental affiliation:

Article 12 – Spouses and registered partners:

‘A person who is the spouse or registered partner of a child’s parent at the time of that child’s birth shall also be considered as a parent, regardless of genetic connection.’

Through this amendment, the ILGA has sought to establish marriage/civil partnership as the legal vehicle for ensuring that same-sex couples’ co-option of a third-party male progenitor would not be able to disestablish their joint parenthood intentions.

In reflecting on each case, it should not be forgotten that access to legal remedies does not justify the unwarranted shifting of the burden of proof to the child’s known and responsible biological father. The shift in the burden of proof is a direct result of gender-neutralising marriage’s presumption of legitimacy. This impacts the public purpose of marriage.

As Dr. Morse reflected on California’s three-parent law 12:

“The solution…is not to amend the law to allow three parents. The solution is to amend the law to remove the possibility of a person unrelated to the child, either by biology or adoption, being counted as a parent. The solution is to stop requiring a gender-neutral reading of a statute that is based on the biological, gendered facts of human reproduction.”

In the UK, this effort to secure the presumption of legitimacy for same-sex married couples is evident in the following memorandum which was submitted in 2013 for the Committee stage of the Marriage (Same Sex Couples) Bill 14:

“In order to help our children and grandchildren, and those of the other 8000+ same sex parents in this country, I would urge you to ensure that the legal situation of our children is exactly like that for any other child.”

“That includes in particular that if they are born into a same sex household by whatever means or adopted by one, both their parents are considered in law as their true parents with equal parenting rights. Should those parents split up or should one of them die, there must be absolutely no question that the remaining parent has full parental rights exactly on the same footing that would apply to children in a conventional marriage.”


The Argentinian ‘Disappeared’ – the child crisis that precipitated formulation of the U.N. Declaration of the Child’s Right to Identity

The impact of the Argentinian junta’s policy towards the children of some 30,000 people who were “disappeared” during the “Dirty War” (1976 – 1982) provoked global outrage 15.

These children were reassigned by law to grow up as part of the “family” of members of the fascist regime. By legal fiat, their kinship was completely erased. Instead, they were bestowed as rewards to officials and loyal supporters of the generals.

In essence, the junta was prioritising kinship through legally-endorsed intention above biological kinship.

As a consequence of this atrocity, the Argentine government that succeeded the junta described the child’s right to identity as follows:

“The child has the inalienable right to retain his true and genuine personal, legal and family identity”.16

This was the basis for Article 8 (the Child’s Right to Identity) in the U.N. Convention on the Rights of the Child.

It is not discriminatory for this right to be asserted on behalf of children, who would be otherwise denied a part of their native identity.


The Church of England’s current official position on same-sex marriage

In 2012, Church of England’s responded to the government consultation on same-sex marriage 17. The summary went:

“The Church of England cannot support the proposal to enable “all couples, regardless of their gender, to have a civil marriage ceremony”.

“Such a move would alter the intrinsic nature of marriage as the union of a man and a woman, as enshrined in human institutions throughout history. Marriage benefits society in many ways, not only by promoting mutuality and fidelity, but also by acknowledging an underlying biological complementarity which, for many, includes the possibility of procreation.”

The statement was widely criticised by scholars and LGBT advocacy groups. For example, in their book, ‘Legally Married, Love and Law in the UK’ 18, Professors Scot Peterson and Iain MacLean insisted that: “these claims are, we shall argue, essentially sectarian Christian ones”.

Yet, the aforementioned ruling of the European Court in Schalke and Kopf v Austria, which is neither sectarian, nor particularly Christian, certainly coheres with the Church of England’s statement.

I would agree with the authors of Legally Married that: “marriage has served multiple purposes, including providing a stable place for children to grow, giving people a secure way of transmitting property and limiting the number of sexual partners people can have”.

However, I would disagree strenuously with their overly reductive conclusion that “because none of this really reflect the ‘essence’ of marriage, the modern, democratic state has the power to change what it recognises as marriage, provided that a majority of people or their representatives support the change”.

As we’ve seen, the objective ‘essence’ of marriage as the founding bond of generative family kinship means that the institution:

  1. Is “geared towards the fundamental possibility of parenthood” (as endorsed by the ECtHR)
  2. Has permanent contingency for offspring, i.e. “the possibility of issue is always supposed to exist in law” (as noted English jurist, Sir William Blackstone put it)
  3. Assures, through the rebuttable presumption of legitimacy, that “the child has the inalienable right to retain his true and genuine personal, legal and family identity” (as was declared in the wake of the ‘lived experience’ of children of the Argentinian ‘disappeared’)
  4. Requires perdurance of kinship ‘offices’, rather than contractual re-definition

To undermine this essence (as exemplified by the International Lesbian and Gay Association, and the aforementioned case law examples) is to deny the objective public purpose of marriage.

David Shepherd



  1. Stanford Encyclopedia of Philosophy: Public Reason
  2. Political Liberalism, John Rawls
  3. Commentaries on the Laws of England (Book 1, Chapter 16), Sir Wiliam Blackstone
  4. Of the good of marriage, St. Augustine.
  5. The Paternity Establishment Theory of Marriage and its ramifications for same-sex marriage constitutional claims, Gage Riley LL.M (Virginia Journal of Social Policy and the Law)
  6. Parish registers were introduced in 1538 by Thomas Cromwell, after his trip around Europe, where he saw that other countries (e.g. Germany, Italy) were already doing this
  7. Commentaries on the Laws of England (Book 2, Chapter 8), Sir Wiliam Blackstone
  8. World Health Organization (WHO). International Classification of Diseases, 11th Revision (ICD-11) Geneva: WHO 2018.
  9. Verfassungsgerichtshof (VfGH), B777/03, 13.12.2003
  15. Memory and Truth in Human Rights: The Argentina Case
  16. Interpreting the Child's Right to Identity in the U.N. Convention on the Rights of the Child, George A. Stewart
  18. Legally Married, Love and Law in the UK’, Peterson/MacLean

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