A Complete Guide to the Arguments for Monogamy

My thoughts on the biblical, theological, ethical, and philosophical arguments for monogamy

This is a live article that I expect to update as needed. If I am missing any relevant arguments, please contact me so I can add them.

My forthcoming book, Poly Theology: In Praise of Unnatural Love (Fordham, 2027), is not a work of apologetics, and as such, I do not attempt to address every possible argument for monogamy or against polyamory. Not only would such a book be tedious in the extreme, it would also be uninteresting. Few if any people have ever changed their minds about topics like this because someone else’s logical defeaters were stronger than one’s own. We are persuaded, if at all, because our experiences cast the world in a new light. In rare cases, a work—a book, a movie, an art exhibit, a poem, or perhaps in a rare instance, a piece of philosophy—invites us into a world that surprises us with its clarity, its moral beauty, its truthfulness. This new world may not necessarily be more rationally sound, but it may feel like a place one wishes to live and make one’s home. I highly doubt my book achieves such a goal, but I am more interested in sketching such a world than I am in defeating all the arguments one might mount against my position.

That being said, there may yet be some utility in constructing a comprehensive list of all the arguments deployed in support of monogamy. This is my aim here. The goal is breadth, not depth. It would be impossible to detail every possible nuance, but I hope to capture as many different arguments as I can—and to offer, as briefly as possible, my responses. I use the word “argument” very loosely. Few, if any, of these are actual arguments in any technical sense of the term. Most of them smuggle in hidden premises or rely on other forms of fallacious reasoning. Still, I am not going to get hung up on logic. I strive to treat each as fairly as possible and to present the most compelling version I can.

I hasten to add that I am not myself arguing that anyone should abandon monogamy. My book, as I make clear throughout, is not written against monogamy but rather argues for including monogamy within the more capacious embrace of polyamory. Monogamy is one way of loving another, but it is not the only way—and Christians have good reasons to make room for different approaches to romantic and erotic affection. In short, my work rejects mononormativity, or what some call compulsory monogamy. Reactions to my work that try to show why monogamy is good miss the point. The issue is not whether monogamy is the right course for many people (it is), but why it must be the right course for all people. The various arguments I outline here manifestly fail to make that case.

I have organized the arguments into the following broad categories: (1) biblical, (2) theological, (3) ethical, and (4) miscellaneous.

Biblical Arguments

The arguments from the Bible are often the ones people reach for first, especially American evangelicals. But they are the least convincing to me for a number of reasons. First, no one, no matter how biblicist, treats the whole Bible as uniformly normative. Everyone negotiates with the text, as Dan McClellan would say. Put in hermeneutical terms, everyone approaches the Bible with an interpretive lens, or at least a set of interpretive guidelines, that is external to the Bible itself. For this reason, theology, rather than the Bible, is everyone’s actual starting point, whether people acknowledge it or not.

Second, the Bible is an ancient library of texts that were written in and for a time, place, and cultural situation that is utterly alien to us today. Apologists like to claim that there is a group called the “people of God” or the “true church” that remains the stable, continuous audience and object of divine revelation from the primal origins of humanity to today, but such a community is a mythical fabrication posited ex post facto as a justification for treating these ancient texts as if they were written with us in mind today—when they were not. Christians, in particular, have little justification for regarding these texts as their own. To be sure, any person can treat a text—whether the canonical scriptures or Shakespeare or the Marvel Cinematic Universe—as their norm, if they so choose. But this is a choice one is free to make, not a command coming from on high. If Christians in the past chose to treat the Bible as normative, Christians today can also unchoose it.

I place these caveats up front because they apply to all of the following textual supports for monogamy.

1. Adam and Eve

One commonly hears that God’s creation of Adam and Eve provides a template for all relationships for all time. Especially important is Genesis 2:24: “Therefore a man leaves his father and his mother and clings to his wife, and they become one flesh.” The Gospels record Jesus echoing this passage (see Mark 10:7–9; Matt 19:4–6). There are many problems with this. First, even if this is a template for marriage, it does not preclude having other relationships—as we see clearly in the accounts of polygyny among the Israelite patriarchs. Many polyamorous people today are married, but also have other partners. Nothing about the Genesis/Gospels passages suggests that this marital bond must be exclusive. Second, the creation accounts in Genesis 1–2 are not read as providing an exclusive template in other contexts. The account of the creation of dualities in Genesis 1—such as “dry land” in distinction from the “seas”—does not deny there are places that mix land and water, such as a marshy bog. We don’t treat the creation accounts as a literal blueprint for the entire created order, so why should we treat Adam and Eve as a blueprint for the entirety of gender norms and sexual relations? Hebrew Bible scholars point out that the text is using the literary device of merism, in which dualities stand in for the whole range of options between these extremes. Perhaps we could treat Adam and Eve’s sexual bond as a similar merism.

2. Symbolism of pairs

The story of the great flood and Noah’s ark is often cited in support of monogamy because of the way the animals are paired off as they board the ark. Pair imagery appears elsewhere in the biblical texts as well. This is not an argument at all but supposedly contributes to an overall picture that sees pair-bonding as a divinely ordained norm for creation. Even if we took this literary pattern (rooted in sexual dimorphism) as normative—and there’s no compelling reason why we should do so—pair-bonding as such does not logically require exclusivity. We see this clearly enough among nonhuman animals, who frequently have multiple sexual partners and at best mate with one partner for a season before moving on to others. But now we are moving beyond literary imagery in the Bible to the argument from nature (see #10).

3. God’s warning against kings having too many wives

Deuteronomy 17:17 reads, referring to God’s instructions on limiting royal authority: “And he must not acquire many wives for himself or else his heart will turn away; also silver and gold he must not acquire in great quantity for himself.” This text is evidently written with the example of Solomon in mind, part of the Deuteronomist morality tale that will later explain God’s judgment on Solomon and others. Besides being obviously connected to a very specific time and place, the text is specifically directed against kings, and the problem with “many wives” here is the concern with idolatry, something that the narrative in Kings will highlight later. The patriarchal assumption of polygyny hardly needs to be pointed out, but that alone renders the text irrelevant to the conversation about polyamory. For the aftermath of the Solomon story, see 1 Kings 11:1–13.

4. Nuptial imagery in the prophetic and wisdom texts

The prophetic and wisdom texts in the Hebrew Bible are full of marital imagery and analogies, most famously Hosea’s unfaithful wife, Gomer, and the erotic literature in the Song of Songs. The patriarchal assumptions built into the prophetic texts are well known and make these stories of little contemporary relevance. Even so, none of these passages makes any kind of normative claim regarding monogamy. Examples of monogamy in the Bible do not translate into compulsory monogamy today.

5. Jesus’s use of the Adam-Eve example as a model for marriage

I have already treated this in principle in my discussion of Adam and Eve above (#1), but I highlight it here since many people claim that, if Jesus says something, it must be a command for all times and places. This is a negotiation with the text built on assumptions that the reader brings to the Bible.

6. The deutero-Pauline use of the nuptial pair-bond as an analogy for the relation of Christ and the Church

According to the author of Ephesians, “Husbands should love their wives as their own bodies. He who loves his wife loves himself. For no one ever hates his own flesh, but he nourishes and tenderly cares for it, just as Christ does for the church, because we are members of his body. ‘For this reason a man will leave his father and mother and be joined to his wife, and the two will become one flesh.’ This is a great mystery, but I am speaking about Christ and the church” (Eph 5:28–32). The passage has a special place in Christianity’s traditional teaching on marriage, since the “great mystery” phrase is the source—thanks to the Vulgate’s translation of mysterion as sacramentum—for the sacramentality of marriage. Whether husband and wife are the analogans for the analogatum of Christ and the Church, or vice versa, does not matter; the point is that many see the exclusivity of Christ’s relationship to the Church as a clear indication that God mandates monogamy.

As Robert Shore-Goss, Will Stockton, and I have all pointed out, however, the analogy here indicates nothing of the sort. The Church, in this analogy, is a corporate body, a collective noun representing a vast, potentially infinite, number of people. If the relation of Christ and Church is supposed to represent the model for marriage, then we have to conclude this is a plural marriage. The attempt to treat the Church here as a singularity, representative of a single person, is a linguistic sleight of hand. I discuss this passage in more detail in my book.

7. Requirements for overseers in the pastoral epistles

In 1 Timothy 3:2, we read that a bishop or overseer must be “married only once” (or, more literally, be “the husband of one wife”). This is about the closest we come to a stated requirement for monogamy, but at best it only applies to people in positions of church authority. As with all of these biblical passages, though, there is no reason why such a text must be treated as normative today, when nothing about the church or society remotely resembles the first-century Mediterranean world. Moreover, many Christians reject the office of bishop entirely, so it makes little sense to still treat this particular requirement as binding.

Theological Arguments

8. One God, one spouse

One of the oldest theological arguments, going back at least to Tertullian, is that monotheism is properly reflected in the practice of monogamy. As Tertullian famously put it, “Unum matrimonium novimus sicut unum deum,” or, “We recognize one marriage, just as we do one God” (De monogamia, 1.4). Tertullian thus grounds marriage in a metaphysics of cosmic unity represented by monotheism. Implied in this position is an analogy of relation between God and humanity that we can formulate as follows: The relationship Christians have with God ought to determine the relationship Christians have with each other. The application of this analogy results in what I call the “argument from monotheism” (AFM). For many, this is the most compelling theological argument for monogamy, and since it comes up so frequently, especially by those enamored with ancient Christianity, I will address it at greater length.

I begin with two important observations. The first is that Tertullian has much more in view than just monogamy here, or to put it another way, “monogamy” means more to him than most people mean today. Notice that he does not say, “We recognize one spouse, just as we do one God.” No, it’s one marriage. Tertullian argues against the practice of digamy, the idea that a person can marry someone new after the death of one’s spouse (or, for those who accept divorce, after the end of one’s first marriage). According to Tertullian, every marriage is an eternal act, and since each person is an immortal soul whose identity persists beyond physical death, the spiritual bond of marriage does not cease with one’s mortal end. (There are some mental and hermeneutical gymnastics that proponents of this position have to navigate in responding to Jesus’s declaration in Mark 12:25 (cf. Matthew 22:30; Luke 20:34–35) that there is no marriage in heaven.) So “monogamy,” for Tertullian, is best understood in its literal etymological sense as “one marriage,” whereas most modern people understand it as “one spouse” or “one partner.” The notion that two people dating could be monogamous would have been linguistically incomprehensible to Tertullian.

My second observation is that some theologians have responded to the AFM by denying that God is singular. Drawing on social trinitarianism, Hugo Córdova Quero and Joseph N. Goh argue that trinitarian perichoresis, the doctrine of mutual indwelling among the divine persons of the trinity, provides a model for human friendship, and since “all friendships are sexual” in the broad sense of involving bodies, love, and desire, the trinity provides a theological grounding for polyamorous relationships. I have rejected this argument in print already, but it is a legitimate response to any theology that draws a social analogy between God and humanity. To be sure, there are versions of the AFM that seem to draw a direct connection between the numerical oneness of God and the numerical oneness of one’s spouse—a crude and clumsy attempt to map divine ontology to human sociality that any theologian should find ridiculous. But the ancient AFM is more nuanced than that. It’s less a numerical template than a metaphysical claim about the protological ground and eschatological end of all creation. With this more sophisticated claim in view, let us turn now to the problems.

First, if the worship of one God determines the proper number of spouses—or sexual or romantic partners—then why not the proper number of pastors, or bosses, or branches of government? Why shouldn’t the Christian only have one friend or one occupation or one residence, all in order to reflect the eternal unity and simplicity of the Godhead? On what grounds do we restrict the argument to the number of spouses or partners one has? Conversely, if Christians accept that there is no binding norm regarding the number of friends, neighbors, coworkers, mentors, supervisors, or political leaders one is permitted to have, then why assume that God’s singularity provides a template for the proper number of sexual and/or romantic partners? Applications of the AFM evince a great deal of special pleading.

That being said, it is manifestly the case that Christians have drawn a connection between monotheism and monarchism—a connection that Erik Peterson famously criticized in his 1935 essay, “Monotheism as a Political Problem.” According to Peterson, “The one monarch on earth—and for Eusebius that can only be Constantine—corresponds to the one divine monarch in heaven.” Whether Peterson was entirely fair to Eusebius is beside the point. What remains beyond dispute is that many have used the AFM with respect to political order, just as many today use it with respect to erotic order. But why apply it to one and not the other, as many Western Christians who embrace parliamentarian or presidential systems of government do? No doubt there are some Catholic integralists with a medieval fetish who argue we must apply the AFM to every aspect of our social lives, but this is obvious foolishness.

Second, a strict application of the AFM to erotic existence ought to make celibacy, not monogamy, normative. (The reason marriage works here is because of the “one flesh” concept, to which I will turn later.) Indeed, this is what we find in the ancient church, where Tertullian, Augustine, and virtually every other early Christian understood celibacy to be the norm and model for Christian life, following the examples of Jesus and the apostle Paul. Many permitted marriage as a concession, but even Augustine, who argued for the sacramentality of marriage, believed that married couples should be celibate once they were finished raising children. That Christians have almost wholly abandoned this way of thinking shows how selectively people apply the AFM today, in ways that call into question the entire argument.

Third, a cosmic metaphysics that tends toward singularity and unity need not conflict with polyamory at all. It is hardly a novel insight to point out that the world is teeming with diversity. The same God that, according to this metaphysical schema, has ordered all things to tend toward simplicity has also generated, in an act of overflowing abundance, a cosmos composed of unfathomable differences and varieties, multiplicity upon multiplicity. There is no contradiction here because those who subscribe to this Neoplatonic metaphysic understand the vast diversity of creation to be grounded ontologically in the singularity of God. The Many live, move, and have their being in the One; they go forth from God and will return to God, in the exitus and reditus of creation that concludes with apokatastasis. There is therefore no reason why polyamory cannot be part of the complexity of human existence. Multiple loves can be ordered toward the singular Good just as multiple human beings, multiple forms of labor, multiple children, multiple works of art, and so on ad infinitum, all reflect the same eschatological end. But we could also emphasize plurality. Polyamory could reflect the manyness of creation, while monogamy, or celibacy, reflects the singularity of the cosmic end. Here I am making essentially the same argument that Augustine makes when he explains why both polygamy and monogamy are sacramental—a point that Christian defenders of mononormativity do not like to admit.

Fourth, and finally, why exactly must our erotic lives reflect some cosmic metaphysical order of being? Christians who draw on these classical arguments from antiquity seem to think this is self-evident, as if the ancient notion that the microcosmic reflects the macrocosmic is an immutable law of nature. These are the types who regard any demurral with respect to the analogia entis as a sign of terminal mental illness. Almost invariably, the ones who make these claims also pine with nostalgia for the aesthetic beauty of the Ptolemaic cosmos and view nominalism as the beginning of the decline of Western society. If you don’t know what I’m talking about, consider yourself lucky. The point is: this notion that “one God” means “one spouse” (or rather one marriage) only makes a lick of sense if one presupposes the entire metaphysical world(view) to which such claims belong. Nostalgic traditionalists may sincerely believe they belong still to that world today, but they are just as modern as the rest of us and are only cosplaying at antiquity. We can firmly set this argument aside.

9. The sacramentality of monogamous marriage

The sacramentality argument has its roots in Augustine’s famous treatise, “On the Good of Marriage,” about which I write at some length in my book. Unfortunately, most people misread this treatise quite badly and assume that sacramentality only pertains to monogamy, even though this is not what Augustine actually says. His concern in this treatise is to provide a theological support for marriage, and since marriage took a polygamous form in the Hebrew scriptures, he provides an account of the sacramentality of both polygamy and monogamy. Here is the key passage:

For this reason, just as the several wives of the ancient fathers were a symbol of our future churches arising from all nations being subject to the one man Christ, so too the fact that our ecclesiastical leader is a man who has had only one wife symbolizes the unity arising from all nations being subject to the one man Christ. . . . Therefore, just as the sacrament of plural marriage of that age was a symbol of the plurality of people who would be subject to God in all nations of the earth, so too the sacrament of singular marriage of our time is a symbol that in the future we shall all be united and subject to God in the one heavenly city. (De bono coniugali, 18/21)

Both polygamy and monogamy, according to Augustine, symbolize different aspects of the eschatological goal of the cosmos. In both cases, the movement is toward a final unity (as in Tertullian’s use of the AFM), but this final unity can be seen from two directions: if we look at creation we see a vast multitude being brought together in the celestial kingdom; if we look at Christ we see a singular leader toward whom all creation tends and in whom they are all united. Both directions are valid, and thus both diversity and unity—both polygamy and monogamy—are sacramentally symbolic.

Of course only one of these remains valid for Christians today, according to Augustine, but his reasoning for this is rooted elsewhere, especially in the New Testament’s references to monogamous marriage (see above). Augustine also has a rather idiosyncratic and mostly implied argument regarding the lack of need for children that doesn’t warrant inclusion in this list.

10. God’s creation of a monogamous natural order

The argument from nature (AFN) is by no means unique to Christians, but Christian theology has long been specially invested in the category of nature for reasons rooted in both theology and ethics—hence the heavy emphasis on natural law in the Catholic tradition.

There are many problems with the AFN, and I discuss them in detail in my book. The tendency to ground morality in nature is a deeply rooted tradition. Humans naturally want to ground their contingent values and norms in structures of nature that are supposedly immutable and eternal, flowing as they do from the god(s) who created all things. In doing so, these people blithely disregard any concerns about the “naturalistic fallacy”—the term for “a kind of covert smuggling operation in which cultural values are transferred to nature, and nature’s authority is then called upon to buttress those very same values” (Lorraine Daston). While C. S. Lewis recognized that “nature does not teach” (Four Loves), this lesson seems to have been forgotten—if it was ever known—in the contemporary Christian debates over love and sexuality.

Theologians like myself who were trained in the school of Karl Barth ought to be inoculated against any temptation to use the AFN. As Barth argued so powerfully, there is no way to reason our way from nature to God, or from the natural patterns and orders to divinely authorized values and norms. God’s revelation is found in Christ, and Christians ought to derive their ethics from the Christ-event. For those informed by dialectical theology, therefore, the only question to ask is whether mononormativity follows from the person and work of Christ. The answer to that, I argue, is an emphatic no. The extent to which Christian proponents of mononormativity pay virtually no attention whatsoever to Christology—instead emphasizing the AFN—is an indirect confirmation of my argument.

Setting aside the problems with the AFN, the argument from the natural world fails even on its own terms. It is no accident that books like Sex at Dawn and The Myth of Monogamy make use of nature to support their argument that nonmonogamy is our natural condition, while monogamy is a cultural imposition placed upon human beings by moral and political authorities as a way to keep society in line. As a principled opponent of the AFN, I reject the pro-nonmonogamy use of the AFN just as much as the pro-monogamy use. But the Sex at Dawn arguments, drawing on the promiscuity of near-human relatives like the chimpanzees and apes—as well as the promiscuity of other animals, like birds—only shows how flawed the arguments from nature all are.

Those who believe that nature teaches their own preferred morality have opened a logical Pandora’s Box that only creates moral chaos, since nature always becomes a magic mirror that reflects whatever it is we want to see.

11. The eschatological goal of humanity in the one heavenly city

I have already touched on the eschatological argument above in discussing Augustine’s use of the AFM and his argument regarding sacramentality. I include it here simply to clarify that eschatology is a discrete doctrinal ground for monogamy alongside the doctrine of God (#8), sacramentology (#9), and doctrine of creation (#10). As I’ve already pointed out, this argument does not support monogamy any more than polyamory. Even if humanity moves toward singularity, it is a plurality of people, nations, and cultures that are on the move—and one can view the eschaton from the perspective of either singularity or multiplicity. In any case, as I observed above, neither necessitates any particular moral conclusion regarding sexuality and erotic love.

Ethical Arguments

12. People are happier in monogamous marriages

When biblical and theological claims fail, people often turn to practical, ethical claims. The first one is that people are happier in monogamous marriages. Evangelicals, who love to tout how happy evangelical Christianity makes people, love to use this argument in their writings, but the research contradicts their claims. In a 2025 report published in the Journal of Sex Research and reported in the Guardian, a team of researchers “found that while some studies found relationship satisfaction was greater in monogamous relationships than non-monogamous relationships, other studies found the reverse to be true, and most found no difference at all.” The same was true regarding measures of sexual satisfaction. In short, “the analysis revealed no overall difference between non-monogamous and monogamous relationships.”

13. Children are happier in monogamous homes

The other practical argument people use is that children are happier in homes with monogamous parents, and thus monogamy ought to be socially compulsory. Inconveniently for them, the research does not support this claim either. A 2024 study published in the Journal of Social and Personal Relationships found that children of polyamorous parents had positive views about their parents’ partners, seeing them as significant adults in their lives who, in addition to being a source of fun, “contributed to their material well-being,” “took care of them,” and “contributed to expanding their circle of friends.”

Speaking as a polyamorous person with two children, I can confirm that my kids view my partners as a very positive part of their lives. My daughter always complains when I tell her that none of my partners is coming over. There’s no question at all that my partners make her life better in so many ways.

Having said this, there are certainly better and worse ways to introduce polyamory to children. For practical details on how to handle this, I recommend reading More Than Two, 2^nd ed., by Eve Rickert and Andrea Zanin (Thornapple Press, 2024).

Miscellaneous

14. The exclusivity of marital self-giving

One of the arguments most central to the Catholic Church’s position in the doctrinal note, Una Caro, is that the act of giving oneself to one’s spouse in marriage is so all-consuming that it has to be exclusive. According to the Vatican, one cannot give oneself to a second or third person, if one has already given oneself fully and truly to the first. I’ve included this under the miscellaneous category because it is not truly theological in nature. One does not have to be a Christian to think the act of marital consent is competitive with any other act of consent with another person.

While this is not a properly theological claim, it conflicts, in my view, with what manifestly is a theological claim—namely, that Christ’s self-giving to humanity, and humanity’s corresponding self-giving in love toward others, is not competitive but rather superabundant. God’s gracious self-giving to one person is hardly competitive with God’s gracious self-giving to another person. Indeed, it is central to the Christian gospel that all people are potentially capable of receiving God’s grace—and for universalists like myself, all people actually do receive God’s grace. If God’s act in Christ reveals the fundamental truth of self-giving elsewhere, then it follows that self-giving is not competitive but rather wholly noncompetitive. God’s self-giving can be infinitely actualized anew, and thus those who participate in God (i.e., all people) are in principle capable of giving themselves anew without restriction.

Parents especially know this to be true. Every parent who cares for their child experiences a daily act of self-giving in which they give themselves wholly to their child in a hundred different ways. Each act of self-giving is complete in itself. Furthermore, a second or third or fourth child does not compete with the first. The parent not only can give themselves wholly to each new child, but they actually do so regularly. Experience proves to us again and again that self-giving is noncompetitive and ever more abundant.

Christianity’s traditional sacramentology further confirms this point. While Christians have often treated marital consent as a unique and separate act, the doctrine of Eucharistic presence shows us that Christ’s self-giving—the gifts of his body and blood—is not a one-time act that cannot be repeated, as the Vatican claims about marriage, but rather an infinitely repeatable act. Christ’s gift of himself to one person does not compete with his gift to another person. A person who partakes of Christ’s body and blood today can partake again tomorrow. Each act is wholly complete in itself because divine self-giving is noncompetitive, always open to new acts and new persons. Divine grace is always inclusive, permanently open to more people.