The Journal of Value Inquiry
https://doi.org/10.1007/s10790-018-9663-8

Is Monogamy Morally Permissible?
Harry Chalmers1,2© Springer Nature B.V. 2018

1 Introduction
Imagine that two partners are in a romantic relationship, and that they are also (orperhaps a fortiori) friends. Yet theirs is not a typical relationship, for the partners
have agreed on a most unusual restriction: Neither is allowed to have additional
friends. Should either partner become friends with someone besides the other, theother partner will refuse to support it—indeed, will go so far as to withdraw her
love, affection, and willingness to continue the relationship.
Many of us, I think, would sense that there’s something morally troubling aboutsuch a relationship. If asked to explain what’s morally troubling about it, we might
say something like this: Friendships are an important human good, and when we’rein a romantic relationship with someone, we should want our partner to have such
goods in her life. Or at least, we should want our partner to be free to pursue such
goods as she sees fit. And part of letting our partner have the freedom to pursue
her own good is to refrain from imposing costs on her when she does so. In thecase of friendship, then, we shouldn’t impose costs on our partner—for example, by
withdrawing our love, affection, or willingness to continue the relationship—if hebecomes friends with someone else. Indeed, many would say that we should go further and actively support our partner’s efforts to find other friends. When our partner
becomes friends with someone else, we should be happy for her—for she now has
an additional source of value in her life.
So far, so good. But now consider this: Sexual and romantic relationships arethemselves an important human good. They, too, contribute to our well-being in
myriad ways—whether through sexual pleasure, through a special kind of emotional support and closeness, through helping us to discover more about ourselves,or through the countless other everyday joys of sharing one’s life intimately withanother. So why not simply be happy for our partner if he found an additional partner, much as we’d be happy for our partner if he found an additional friend? Is* Harry Chalmers
harrison_chalmers@brown.edu
1

Brown University, Providence, RI, USA

2

228 Waterman St. #11, Providence, RI 02906, USA

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disallowing one’s partner from having additional partners any better than disallowing one’s partner from having additional friends?1
Questions like these are rarely asked, and even less often taken seriously. Mostof us assume that there’s nothing morally suspect about having one’s relationship be
dyadic and exclusive—that is, involving exactly two partners, and permitting neither partner to engage in romantic or sexual activity with anyone outside the relationship.2 We tend to assume, in other words, that monogamy is morally permissible—that there must be some morally relevant difference between disallowing one’s
partner from having additional partners and disallowing one’s partner from having
additional friends. Yet finding a morally relevant difference between the two is much
more difficult than it might seem, for, as I’ll now argue, the standard defenses orjustifications of monogamy all fail. I take this failure to be evidence that the “noadditional partners” restriction of monogamy is in fact morally analogous to the “noadditional friends” restriction described earlier. Just as a categorical restriction on
having additional friends is immoral, so, too, is monogamy’s categorical restrictionon having additional partners.

2 Monogamy on the Defensive
We’ve seen above how monogamous restrictions are prima facie analogous to a
morally troubling “no additional friends” restriction. The task for those who would
defend monogamy, then, is to find a morally relevant difference between the twokinds of restriction. There are broadly two ways in which one might try to find sucha morally relevant difference: (1) argue that the “no additional friends” restriction has bad-making features that monogamous restrictions lack, or (2) argue thatmonogamous restrictions have good-making features that the “no additional friends”
restriction lacks.
It is easy enough to imagine how one might go about the first of these strategies. One might say, for example, that a restriction on having additional friends
would be much more onerous than monogamous restrictions. After all, to refrainfrom having additional partners merely requires that we keep our romantic andsexual activity to one person at a time, and surely that’s not so hard or extraordinary. But to refrain from having additional friends would require a much more
sweeping change to our social life. Were we to restrict ourselves from having
additional friends, we’d have to make sure not to be too friendly to others weknow, not to laugh or chat too much with them, not to invite them to spend timewith us, not to accept their invitations to spend time with them, not to go out of1
A handful of other philosophers have raised a similar question. See Bryan Weaver and Fiona Woollard,“Marriage and the Norm of Monogamy,” The Monist, Vol. 91, No. 3-4, (2008), pp. 508-510, along withNatasha McKeever, “Is the Requirement of Sexual Exclusivity Consistent with Romantic Love?” Journalof Applied Philosophy, Vol. 33, No. 2, (2015), p. 1. Unlike me, however, Weaver, Woollard, and McKeever go on to hold that monogamy is morally permissible in the end.
2
Here I draw from Carrie Jenkins’s useful definition of monogamy. See Carrie Jenkins, “Modal Monogamy,” Ergo, Vol. 2, No. 8, (2015), pp. 180-181.

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our way to support them when they’re in need, not to accept their support when
we’re in need—in short, we’d have to make sure that our relations to all others(save our partner) stay businesslike at best. Such a straightjacketed social life issomething no minimally decent person would want for her partner.
I grant that a restriction on having additional friends would be a good deal
more onerous than monogamous restrictions, and that this is, in some sense, amorally relevant difference between the two kinds of restriction. Yet it is a morally relevant difference only in a weak sense, namely that it suggests that the
restriction on having additional friends is morally worse than monogamous
restrictions. And this, of course, is not what the defender of monogamy needs—
since however worse the restriction on having additional friends is, it could, for
all we know, be that monogamous restrictions are still morally impermissible.
Some morally impermissible actions, after all, are worse than others; ceteris paribus, it’s morally worse to assault someone than to tell him a lie, yet that hardly
suggests that lying is morally permissible.
What the defender of monogamy needs, then, is not simply to show thatmonogamous restrictions are morally better than the restriction on having additional friends, but that monogamous restrictions are morally permissible. And to
do that, the defender of monogamy will have to go beyond strategy (1) above;that is, she’ll have to go beyond simply arguing that the restriction on having
additional friends has bad-making features that monogamous restrictions lack.
After all, however many unique bad-making features the restriction on additional
friends might have, what matters is whether there is even one bad-making featurethat it shares with monogamous restrictions. I’ve suggested above that there isa bad-making feature they share: Both restrict one’s partner’s access to a prima
facie important human good—in one case, (additional) friendships, in the other,(additional) sexual and romantic relationships.
At this point, the defender of monogamy might say that while both kinds ofrestriction have this apparently bad-making feature, this is a problem only for the
restriction on having additional friends—for only this latter restriction seems tolack any justification. There’s simply no good reason why partners should restrict
one another from having additional friends. When it comes to sexual and romantic relationships, however, there are good reasons why partners should restrict
one another from having more than one at a time. Here the defender of monogamy is opting for strategy (2) above—that is, arguing that monogamous restrictions have good-making features that the restriction on additional friends lacks.
This is a more promising route than strategy (1), for, to the extent that monogamy
has unique good-making features, that could explain why monogamy is morally
permissible while the restriction on having additional friends is not. Let’s consider, then, some attempts to find unique good-making features of monogamy—in
short, some defenses of monogamy.
Here, regrettably, I cannot consider all the defenses of monogamy on offer. In
particular, I must set aside some of the more sophisticated and recherché defenses
in favor of those that are simpler, better known, and more likely to resonate withmonogamists in general. Given the very limited state of the literature on the topic,
even these latter kinds of defenses of monogamy have not yet received much critical13

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attention. In addressing them here, I hope to show that defending monogamy turns
out not to be nearly as easy as most people assume.
2.1 The Specialness Defense
One common defense of monogamy is that monogamy helps one’s romantic relationships to be special. Many think that there is or can be a distinctive value inchoosing, and being chosen by, just one person.3 This distinctive value, the thought
continues, is enough to justify monogamy.
The most obvious problem with this defense of monogamy is that it seems toapply equally to the case of friendship. If having only one partner makes for a more
special romantic relationship, and if the value of this specialness is sufficient to justify monogamous restrictions, then it is difficult to see why having only one friend
would not likewise make for a more special friendship, and why this specialness
would not likewise justify the “no additional friends” restriction described earlier. But clearly such an appeal to specialness could not justify the “no additional
friends” restriction. Having additional friends does not make any particular friendship less special. And the same holds true for affectionate or loving relationships
more broadly. Consider, for example, the relationship between parents and children.
We do not generally think that having strictly one child is a way of making the parent-child relationship more special; were one to have more children, would not one’s
relationship with the first child remain just as special? And would not one’s relationships with the other children be just as special as one’s relationship with the firstchild? If indeed that is so, then those who defend monogamy on grounds of specialness must point out a relevant difference between romantic relationships and otherloving relationships—some difference in virtue of which one could have a more special romantic relationship by having only one partner yet not have, say, a more special parent-child relationship by having only one child. It is far from clear whether
there is such a difference, much less what it might be.
I can think of only one reason why one might think that monogamy helps one’s
relationships to be special: if one understands “special” to mean “exclusive.” (Thissense of “special” occurs in sentences like “There will be special seating for us at
the event.”) Under this understanding of “special,” monogamy indeed helps one’s
relationships to be special; that, of course, follows trivially from equating “special”
with “exclusive.” But surely there is more to this defense of monogamy than thetrivially true claim that monogamous relationships are more exclusive than nonmonogamous relationships. We must, then, find another understanding of “special.”
I propose that we understand “special” here to mean “highly valuable.” This,I think, is a much more natural sense of the word to use when talking about

3
McKeever (op. cit., p. 9) is among those who defend monogamy by appealing to specialness: “[Sexualexclusivity] provides the lovers with a space that belongs to them, together, and to them only. Their sexual world becomes a world that only they inhabit…. This is valuable in itself, as a way of celebrating theuniqueness of the relationship and its intrinsic value…. [S]haring sex exclusively can be one way of making the relationship distinct and special.”

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Is Monogamy Morally Permissible?﻿	loving relationships (e.g., “My relationship with this close friend is very special”).
If monogamy helped relationships to be more special in this sense, that would certainly be a point in its favor. Notably, however, it does not follow from the fact thatmonogamy makes a relationship more special in the first sense, the sense of exclusivity, that it makes a relationship more special in the second sense, the sense ofbeing highly valuable. Or at least, if it does follow, it is not at all obvious. Especiallyin light of the other examples of loving relationships, such as parent-child relationships, I cannot come up with any good reason to think that exclusivity somehow
helps a relationship to be highly valuable.4 What seems more likely is that it is only
if one conflates the above two senses of “special” that this defense of monogamy
will seem plausible.
2.2 The Sexual Health Defense
A further defense of monogamy centers on sexual health. The idea is that having
multiple sexual relationships at a time leads to a much higher risk of sexually transmitted infections (STIs) and, in heterosexual relationships, of unwanted pregnancy.
If partners want to reduce such risks, they are well advised to restrict each other to
one sexual relationship at a time—in other words, to embrace monogamy.
Sexual health is an important concern. For multiple reasons, however, it fails tojustify monogamy. First, a concern for sexual health is simply too narrow to justify
the full range of monogamous restrictions. After all, monogamous restrictions apply
not only to sex, but to activities like intimate dancing and outercourse, and often toemotional intimacy as well. Even if the sexual health defense succeeds in justifying
monogamous restrictions on sex, it does little to justify these other restrictions thatare a part of monogamy.
More damningly, the sexual health defense does not even succeed in justifying
monogamous restrictions on sex—not in light of the various methods of contraception and safer sex. Through properly using condoms and other methods of safer sex,
partners can dramatically reduce the risk of STIs and unwanted pregnancy.5 Somemight object that even with such methods, the risk is not wholly eliminated. But
then, there are risks of all kinds to be found in activities that we nevertheless findworthwhile. Driving, biking, and playing sports, for example, all involve risks, particularly risks of bodily harm or even death. Yet it would be silly to say, merely onthat basis, that we ought not to engage in such activities, or that it is okay for partners to forbid one another from engaging in them. I see no reason for thinking that
non-monogamous sex is any different.
4

Writing in a similar context, Hallie Liberto suggests that there’s something positively troubling in connecting the value of a relationship to its exclusivity. Specifically, such an attitude appears to objectify
one’s partner. Or, as she puts it, “When we treat our partner’s sexuality as more valuable to us because
access is limited, then we treat it in the same way that we treat a privately owned painting” (Hallie Liberto, “The Problem with Sexual Promises,” Ethics, Vol. 127, (2017), p. 411).
5
For accessible and comprehensive information on how the various methods of safer sex reduce the riskof STIs and unwanted pregnancy, I recommend Planned Parenthood’s website (https://www.plannedparenthood.org).

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A genuine, intellectually honest assessment of risk must take into account not
only the fact that a risk exists, but the nature and extent of the risk weighed against
the benefits of the activity that carries the risk. In order to justify monogamy ongrounds of sexual health, one would have to show that the risk of STIs and unwanted
pregnancy is so serious, and the benefits of non-monogamous sexual activity sominor, that it makes sense for partners to refuse one another even the possibility of
taking on board a new sexual relationship. To be sure, some cases may well fit thisdescription, especially in areas where protection, contraception, and STI testing areunavailable. However, for those of us in developed countries with access to contraception, protection, and STI testing, considerations of sexual health alone are not
likely to justify monogamy.
Risk assessments ought generally to be done case by case, with open discussion
between partners. Admittedly, even for those who do have access to sexual healthresources, in some cases sex with another may not be worth the risks involved. For
example, suppose that a certain person refuses to discuss his sexual history, gettested, or use protection. In such a case, clearly each partner in a couple would beright to bar one another from sex with that person. Acknowledging the potential forcases like this, however, does nothing to justify the across-the-board restrictions
inherent to monogamy, for there are other cases in which the risks are much lower(say, when a new potential partner is perfectly willing to discuss his sexual history,
get tested, and use protection). Embracing non-monogamy, it is essential to remember, does not at all mean that one must be open to any sexual contact between one’s
partner(s) and others. Rather, it means that one will, at least in principle, be open
to sexual contact between one’s partner(s) and others in at least some cases. Moreprecisely, if one is to be consistent in one’s non-monogamy, one should be open tosexual contact between one’s partner(s) and others in any case in which there is no
good reason not to be open to it.
2.3 The Children Defense
The next defense of monogamy centers on raising children. Specifically, one might
think that monogamy is the healthiest relationship style for raising children; children develop best when they see their parents as romantically involved only with one
another. Of course, this point could justify monogamy only for partners who havechildren, particularly young children; it does nothing to justify monogamy for partners who are child-free or whose children have grown up. Still, many partners do infact have young children. So if indeed in those cases monogamy is justified, that’s astrong point in monogamy’s defense.
There are multiple problems with this defense of monogamy. The first is that,even if we assume that it is harmful to children to see their parents be romanticallyinvolved with others, it does not follow that parents ought not to be romanticallyinvolved with others. To draw an analogy, we might suppose that watching violent
films is harmful for young children. It does not follow, of course, that parents ought
not to watch violent films. They need only make sure that, if they decide to watch
violent films, they do so when their children are away or asleep. Similarly, even13Is Monogamy Morally Permissible?﻿	

if young children need to see their parents as monogamous, parents are nevertheless free to have other relationships; they need only keep their other relationships
private. Perhaps this will strike some as wrongfully hiding the truth from children.
Yet that objection seems odd; since when are parents not allowed to have a private
life? Moreover, as a matter of course, parents refrain from exposing their children tothings that the children are considered too young to confront or understand—not theleast of which happen to be the parents’ own sexual relations. Why would the parents’ sexual relations with others be any less okay to keep private?
Thus far in my response I have assumed that children develop best when they
perceive their parents as monogamous. As it turns out, there is no good evidence
for this assumption; it is mere speculation, with about as much plausibility as the
speculation that children develop best with heterosexual parents. By the evidence
available, whether a family environment is monogamous or non-monogamous does
not by itself have any bearing on how suitable it is for children.6 Apart from havingbasic, material needs met, what matters most for children is having an ample amountof love, support, acceptance, and understanding. There is no reason to suppose thatparents must be monogamous for their children to have the love, support, acceptance, and understanding that every child needs. If anything, for parents to have otherpartners who help provide these needs is likely to be helpful, not harmful, to thechildren.7
Still, some might feel a lingering worry. One feature of non-monogamous relationships, after all, is that partners break up. A pair of non-monogamous parents willoften have a gradual stream of partners coming into and out of their lives over theyears. If the children get to know and to spend time with these partners, the children
are prone to becoming attached. Thus, when either parent breaks up with a partner,
does that not present a hardship for the children? Won’t the children feel hurt andabandoned?
It is indeed true that non-monogamous parents sometimes break up with theirpartners—including partners who have become a valued part of the children’s lives.
In not at all such cases, however, will this present a hardship for the children; particularly when the breakup is amicable, the ex-partner might well remain friends
with the parents and thus continue to have a place in the children’s lives. Of course,
in cases where the ex-partner does depart from the children’s lives, whether for having broken up with the parents on bad terms or for any other reason, that is indeed
saddening for the children. Ultimately, though, such a prospect is not a good reason
6
Unfortunately, empirical research on children in non-monogamous families is still quite limited. From
what research does exist, however, it seems that children in non-monogamous families do every bit aswell as children from monogamous families. In her pioneering work on the subject, sociologist Elisabeth Sheff found that the children she interviewed from non-monogamous families “[o]verall… seemed
remarkably articulate, intelligent, self-confident, and well adjusted” and “appeared to be thriving with theplentiful resources and adult attention their families provided” (Elisabeth Sheff, The Polyamorists Next
Door: Inside Multiple-Partner Relationships and Families (Lanham, MD: Rowman & Littlefield, 2014),
p. 135).
7
Jenkins (op. cit., p. 184) raises a similar point. For a more extended discussion, see Daniela Cutas, “On
Triparenting. Is Having Three Committed Parents Better than Having Only Two?” Journal of Medical
Ethics, Vol. 37, No. 12, (2011), 735-738.

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for parents to stick to monogamy. After all, there are all kinds of figures who giveinvaluable support and guidance to children, and to whom the children become
attached, yet who have only a passing presence in the children’s lives. As children
grow older, they must say goodbye to valued teachers, coaches, camp counselors,
grandparents, pets, and friends. I doubt anyone would suggest that it would be betterin the end if such figures were never an important part of children’s lives in the firstplace, just so the children could be spared the pain of seeing them go. Even with thepain of saying farewell, the children are better off for having known them. But then,
why would the same not hold true in cases where non-monogamous parents cut ties
with one of their partners?
A further point is that the above worry—the worry about how children might beaffected by breakups between parents and their partners—applies not only to nonmonogamous parents, but also to monogamous single parents. A monogamous single parent might well have a series of partners gradually coming into and out of herlife as her children grow up. Is the risk of the children’s being harmed by breakups so grave that monogamous single parents ought not to start new relationships?
Surely few would want to say this.8
There is only one further way I see of defending monogamy by appealing to theneed to protect children, and that is to charge that non-monogamy is too impractical for raising children: Parents simply do not have enough time or energy to devote
themselves adequately both to their children and to (multiple) other partners. Butthat leads us to the next defense of monogamy, a defense that deserves a section of
its own.
2.4 The Practicality Defense
One might defend monogamy on practical grounds. One might argue, for instance,that while it would be nice if we could devote our romantic attention to unlimited
partners at a time, our time and energy are finite. Being monogamous, then, is a way
for us to ensure that we do not, by taking on too many partners at a time, become
unable to devote the time and energy to our partner—and, if we have them, our children—that are called for in a relationship.
There’s no doubt that we humans are limited in our time and energy. Yet this doesnothing to justify monogamous restrictions. The mere fact that we are incapable ofdevoting our romantic attention to unlimited partners at a time hardly justifies setting the limit to one. After all, we are likewise incapable of having unlimited friends
at a time, but surely that doesn’t justify a “no additional friends” restriction like theone described in the introduction.
Another problem with the practicality defense is that it could be directed at any
use of time and energy that does not involve one’s partner or children. Should one
pursue a hobby or spend time with one’s friends, then—barring the prospect of having one’s partner and children along for everything one does—one will be spending

8

Thanks to an anonymous referee for suggesting this point to me.

13Is Monogamy Morally Permissible?﻿	time and energy away from one’s partner and children. Surely there is nothing wrong
with this. Indeed, it is a normal part of healthy relationships. But in light of this, thepracticality defense is in trouble. Since it is acceptable for one to spend time andenergy away from one’s partner and children, why should it matter if some of thetime and energy one spends away from one’s partner and children happen to involvesex and romance with others? From the standpoint of time and energy management,
at least, there seems to be nothing wrong here.
There is, however, an improved version of the practicality defense. Specifically,
one might propose that not merely time and energy management, but considerationsof people’s emotional limitations can justify monogamy. Romantic relationships,
after all, require us to extend our concern to others, to be wrapped up in their world,
to become vulnerable to them. And, no matter how much we may wish it were otherwise, we can love and care for other people only so much. Given the emotionallydemanding nature of romantic relationships, along with our own emotional limitations, it is entirely legitimate to focus our attention on developing one relationshipat a time—and to expect our partner to do the same. In at least some cases, partners
who commit to directing their attention in this way will have a deeper, more manageable, and more satisfying romantic life than they would if they spread themselvesmore thinly.
While more plausible than what came before, this new version of the practicality
defense has its own set of problems. The first stems from the fact that not all forms
of non-monogamy involve openness to multiple emotionally intimate relationships
at a time. In some forms of non-monogamy, the focus is on sex rather than emotional intimacy. Even if we grant that a single romantic relationship will leave us
emotionally exhausted, allowing casual sex on the side (but nothing beyond that)
seems just as much a solution as opting for full-blown monogamy.
But surely this won’t do, some will object—for what starts as a bit of casual sex
on the side can all too easily become something more serious. If we wish for security and stability in our romantic relationships, then, we must stick to monogamy.
This maneuver, I must say, strikes me as tenuous. Surely much of the time, we canreasonably be confident that the potential for a close emotional bond with anotheris low, and that the connection is purely or primarily sexual. Nevertheless, we canset that issue aside. For there lurks a deeper problem here. To see what it is, let us
imagine a case in which a casual sexual relationship does morph into something
more serious. It begins with two acquaintances who decide to indulge in the occasional hookup. At this stage, their connection will not be emotionally draining, since
it lacks an emotional bond altogether. Now imagine, though, that over time theirconnection comes to hold a deeper emotional significance. The two come to have
not just a sexual acquaintanceship, but a sexual friendship. Surely this new stageof their connection need not be emotionally burdensome—not more than any otherfriendship, anyway. Now imagine, lastly, that their sexual friendship becomes more
serious still—indeed, that it becomes a close friendship. Must it now be emotionallyburdensome?
No again, it seems. After all, close friendship is not something we in general findemotionally taxing—more truly the opposite, in fact. Rather, in our close friendships
we find a source of love, support, and empathy. And even when close friendships

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do contain challenges, such as moments of stress or tension, these do not tend to
be dominant or definitive features of the friendship; they are the exception rather
than the rule. On the whole, our close friendships energize, encourage, and empower
us. And their doing so does not appear at all contingent on whether they happen to
involve sex. Thus, we may conclude that the above partners’ connection in its final
stage need not be emotionally draining. And now for the crucial point: Their connection in its final stage just is a romantic relationship. In having a sexual relationship that is equally a friendship—and not just a friendship, but a close friendship—
the partners hold a deep bond both physically and emotionally. It is precisely thiskind of bond that is a hallmark of romantic relationships. The result we face, then, isthat romantic relationships need not be so emotionally burdensome after all.
Why might it seem to so many that romantic relationships, by their very nature,
leave us emotionally exhausted? One thing that might explain the popularity of thisthought is the common assumption that one’s partner is supposed to meet all of
one’s deepest personal needs, such as love, sex, and companionship. In holding thisassumption, partners subject themselves to a more stringent standard of behavior in
their relationships. Any failure of either partner to meet the other’s personal needs
will present itself as a grinding obstacle that must be set straight, should it be possible, in order to have a proper relationship. To live under such a standard can no
doubt be tiring.
The assumption that one’s partner is supposed to meet all of one’s personal needs,
however, is itself a relic of monogamy. If one is allowed to have no more than one
partner at a time, then it is easy to see why one’s partner would be expected to meetall of one’s personal needs. When no one else is allowed to provide sex or romantic
love, failures of one’s partner to meet these needs will, barring cheating, mean thatthese needs will go unmet. But absent a background of monogamy, the assumptionthat one’s partner is supposed to meet all of one’s personal needs collapses. If one
is allowed to have multiple partners at a time, after all, then failures of a certain
partner to meet some of one’s personal needs do not have to be grinding obstacles in
the way of a satisfying romantic life. For one can simply have those needs be met byanother partner. For example, for some partners the focus can be on fulfilling sexual
needs, while for other partners the focus can be on emotional needs.
While such arrangements might at first seem strange, a similar pattern holds infriendship: We do not expect a friend to be everything, to provide everything, tomeet all of our personal needs. (Indeed, imagine that one did hold such an expectation of a friend—would we not find this neurotic and absurd?) Some friends arevaluable to us in some ways, while other friends are valuable to us in other ways.
Why should it not be the same with our partners in romance?

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2.5 The Jealousy Defense
I arrive now at what appears to be the most popular defense of monogamy, thedefense that comes almost immediately to everyone’s mind: the appeal to jealousy.9
In jealousy our thoughts and feelings flail about within a mire of crippling anxiety, despair, self-loathing, sometimes even rage. And it all seems to come from seeing our partner take an interest in someone else. What option is left to us partners,
then, but a mutual promise to forsake all others? At stake here is our comfort, ourhappiness, our sanity. Only monogamy can keep us safe from jealousy; that is its
justification.10
In the face of the sheer power of jealousy, it’s easy to lose sight of the question of
why we feel jealous. Yet that is a question worth posing here at the outset, for jealousy, when we pause to reflect on it, truly is odd. After all, when we see our partner
find joy in someone else, would it not make more sense for us to be happy for her?
Would it not be truer to our love, truer to our good will, to share in her joy? Surely
delight and encouragement are the right, the sensible, the mature—truly, one might
say the loving—reaction to our partner’s good. Why, then, when our partner’s good
happens to involve an interest in someone else, do we feel so awful instead?
The answer, I think, can only be that we feel jealous precisely because we areless rational and less mature than we could be. Were it not for certain unreasonable
fears and preconceptions that burden our minds, we would react to our partner’s newlove in the way that is so evidently called for: by simply being happy for him. Whichfears, which preconceptions keep us from this? First and foremost here is the fear of
losing our partner to someone else.11 When we feel dread at the prospect of our partner’s finding a new lover, what most often underlies our feelings is the worry thatour partner will come to desire her not in addition to us, but instead of us.12 Second,
what breeds jealousy further is the common assumption that if our partner wishes
for another or finds happiness in another, this means that there’s something wrong
with us and our relationship—in short, that we’re “not enough” for our partner.13
When we see any indication of interest in someone else as a sign that our partner is
9In their studies of the public’s perceptions of non-monogamy, Conley et al. find that “a major perceived benefit of monogamy is the avoidance of jealousy” (Terri Conley, Ali Ziegler, Amy Moors, Jes
Matsick, and Brandon Valentine, “A Critical Examination of Popular Assumptions about the Benefits
and Outcomes of Monogamous Relationships,” Personality and Social Psychology Review, Vol. 20, No.
10, (2012), p. 7).
10
Roger Scruton is among those who press this point. See Roger Scruton, Sexual Desire (New York,
NY: The Free Press, 1986), p. 339.
11
See Aaron Ben-Ze’ev, “Jealousy and Romantic Love,” in Sybil Hart and Maria Legerstee, eds., Handbook of Jealousy: Theory, Research, and Multidisciplinary Approaches (Chichester, UK: Wiley-Blackwell, 2010), pp. 42-43.
12Indeed, so central to jealousy is the perceived threat of losing one’s partner to another that someresearchers prefer simply to make this the very definition of jealousy (Conley et al., op. cit., p. 7).
13
For some data in support of this point, see Gregory White, “Jealousy and Partner’s Perceived Motives
for Attraction to a Rival,” Social Psychology Quarterly, Vol. 44, No. 1, (1981), 24-30. See also Conley
et al. (op. cit., p. 6), who note that “[g]enerally, monogamous people assume that others enter a CNM[consensually non-monogamous] relationship only if they are dissatisfied in their relationship with theirprimary partner.”13

H. Chalmers

dissatisfied with us, it’s only natural for us to feel hurt at the sight of our partner taking interest in another. Although other factors can play a role in jealousy, it is these
two—the fear of losing our partner to someone else, along with the assumption thatfor our partner to show interest in someone else is a gesture of dissatisfaction with
us—that appear to lie most insidiously at its root.
Now that we have in mind these key factors behind jealousy, we are in a better position to consider whether monogamy is the solution. Many people take it asobvious that monogamy is the only answer, or at any rate the best answer, to jealousy. In fact, however, this is far from obvious. As is well known, monogamy does
not preclude jealousy; indeed, it is a commonplace in monogamous relationships toworry whether one’s partner is interested in someone else, or even simply whether
she might become interested in someone else. Why is this? Wasn’t monogamy supposed to ensure freedom from jealousy? As it turns out, it’s no surprise that monogamy fails to preclude jealousy. For monogamy is not a way of addressing the factors,
described above, that underlie jealousy; instead, it is merely a capitulation to them.
I use “capitulation” quite intentionally here. What I mean by it is that, rather thanconfronting the underlying needs or problems that jealousy indicates, monogamy isinstead simply a way of avoiding behaviors that trigger jealous feelings, even at thecost of restricting the partners’ freedom and well-being. To see in more detail what I
mean, let’s consider an example from another context. Imagine that two partners are
beset by jealousy not of the romantic or sexual kind, but jealousy of a kind that centers on one another’s accomplishments in the workplace. Each fears seeing his own
work become outmatched by that of his partner. This fear, in turn, feeds on the partners’ shared assumption that if one’s partner is producing superior work, that shows
one’s own work to be inadequate. In the face of their jealousy, the partners mutuallycommit to putting out only mediocre work from now on; that way, neither will feel
jealous of the other’s accomplishments.
Now let us ask ourselves whether the partners have chosen a healthy, desirable
solution to their jealousy. Clearly not—and not simply because the doubts and disquiets of jealousy remain likely to lurk in the partners’ minds. (“Oh dear—what if hegets careless on his current project and ends up producing something good?”) Moredeeply, what is wrong is the very spirit, the very direction of the partners’ wholeapproach to the matter. Rather than running away from their jealous feelings, as it
were, by restricting their behavior so as not to trigger them, the partners should confront their jealous feelings head-on. They should take responsibility for their feelings, seek to overcome their insecurities, work to free themselves from the fears andfalse assumptions that give rise to the problem in the first place. They should, inshort, take the path of greater maturity.
I’d now like to suggest that monogamy is analogous to the above case. Monogamy, too, is a capitulation to jealousy. Just as with workplace jealousy, the proper
response to romantic and sexual jealousy is not to restrict our behavior in order toavoid triggering it, but instead to confront it head-on. Below I’ll say more about how
we can do so. First, though, we should take a moment to recognize just how counterproductive monogamy’s capitulation to jealousy really is.
Not only does monogamy fail to be a guarantee against jealousy. Worse, bycapitulating to jealousy, monogamy in fact perpetuates it. To see how, consider the13

Is Monogamy Morally Permissible?﻿	

opportunity costs that are a part of monogamy. If you are in a monogamous relationship, your partner has committed not to be with anyone else. By this simple fact,monogamy makes it much more natural to worry about keeping your partner. For
in being with you, your partner is forgoing other options, and the only way for him
to openly pursue those options is to end his relationship with you. From here seeps
the unshakable awareness: “The more desirable those other options seem, the moredesirable it will seem to my partner to leave me for someone else.” It’s this kind of
relationship style that breeds jealousy so well, that stokes the fear that your partner
will decide to “trade up.” Under monogamy, it’s all too natural to be concerned not
simply that your partner likes you, but that he does not like anyone else more.
Together with this heightened fear comes a sense of pressure: pressure to be more
impressive than the others, to ensure that you always one-up the “competition” foryour partner. (How sad it is that monogamy makes the word competition come sonaturally here, when talking about something like the love of your partner!) Anda trying task this often is. As noted earlier, monogamy fosters an expectation thatyou’re to fulfill all of your partner’s personal needs; after all, it’s not as if she isallowed to reach out to other partners here. Naturally, facing such a high standard
only makes it easier to feel insecure, to worry whether you’re really enough for yourpartner. In every mistake, every shortcoming lies an invitation to wonder, “Might
this just have led my partner to think, even if only for a moment, that it’d be nicer if
someone else took my place?” All of this builds up a perfect environment for jealousy to fester.
As these considerations suggest, monogamy is not the solution to jealousy;
indeed, it is largely what makes jealousy so persistent a problem in the first place.
The kind of context in which jealousy most readily stews is that of a refusal toshare, that of competition for something—precisely the kind of context sustainedby monogamy. By abandoning monogamy, we destroy much of the lifeblood of jealousy. Accordingly, it is with the abandonment of monogamy that the real solution tojealousy begins.14
But abandoning monogamy is only the first step. Other steps remain. Rather thancapitulating to jealousy in the vain hope that that will make it go away, as monogamy does, these further steps involve confronting jealousy directly. That is how
we can best be assured of being free of jealousy in the end—or, at the very least,
assured that whenever jealousy does arise, we will have healthy, effective ways ofcoping with it and working through it.
Here, more specifically, are some of the key steps by which we can confront jealousy directly. The first is simply to realize how irrational jealousy is. Jealousy is built
on a bed of unreasonable fears and false preconceptions. Consider, first, the assumption that for your partner to feel interest in someone else is a sign of dissatisfaction
14

Note that this conclusion is consistent with what Conley et al. (op. cit., p. 7) conclude in their reviewof the relevant research: “Although only a few studies have examined jealousy in CNM [consensually
non-monogamous] relationships, their results indicate that jealousy is more manageable in these relationships than in monogamous relationships… and is experienced less noxiously…. Despite the common
belief that monogamy is a way to prevent feelings of jealousy… research has shown that levels of jealousy were actually lower for those in CNM relationships than in a monogamous sample….”

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H. Chalmers

with you, a sign that you are “not enough” for him. Implicit in this idea is a viewof relationships as driven by a need to correct for deficiency. In such a view, beinga good partner is like filling an empty receptacle: If you do your job well, there isnothing left to be filled, nothing that your partner could possibly gain from having
another partner. Thus, if your partner does become interested in someone else, it
must be because of some deficiency in your partner’s life that you’ve failed to offset,
some portion of the receptacle that you’ve failed to fill. But this is a false and pernicious view of relationships. It’s not—or at least, it need not be, and arguably should
not be—as if we form relationships as a way of correcting for some problem or deficiency in our lives; rather, we form relationships because they are a source of value
within our lives and within the lives of our partners. And there’s no tension between
having a perfectly fine relationship with one partner while acknowledging that additional relationships could make for additional sources of value within our life andwithin the lives of others.15
Once more, we might consider an analogy with friendship. To make a new friend
is no indication at all that there’s something wrong with an existing friend. It doesn’t
even remotely suggest that the existing friend “isn’t enough.” (And let’s imagine
now that the existing friend did confront us with such a charge. “What’s wrong—am
I not enough for you?” he demands. How sadly neurotic, how appallingly petty andimmature this would be!) After all, at least in typical, healthy cases, we form friendships not to correct for some deficiency, but to add a source of value to our lives andto the lives of our friends. The same, it seems, holds true for love. Just as we haveno reason to feel hurt when a friend of ours makes an additional friend, we have noreason to feel hurt when a partner of ours finds an additional partner.
Consider, next, the fear that is so central to jealousy: that of losing a partner tosomeone else. When in the grip of this fear, we often forget to ask ourselves a simple
yet crucial question: If our relationship is mutually fulfilling, shouldn’t we trust ourpartner not to leave us for someone else? Of course, for many of us, being monogamous will have made this a more difficult question to answer. As noted earlier, undermonogamy the stability of our relationship is not just a matter of whether it’s fulfilling on its own terms; rather, it’s likely also to be a matter of whether our partner
perceives other potential relationships as more fulfilling. To the extent that she does,
she’ll have reason to leave us for someone else. But let’s assume here that we’vealready taken the first step toward overcoming jealousy, namely abandoning monogamy. Absent monogamy, for our partner to suspect that another relationship would
be fulfilling, or even more fulfilling than his relationship with us, need not present a
reason for him to leave us. For we’ve left it open to him to pursue others while staying with us; we haven’t forced him to choose between us and another. With this inmind, let’s come back to the above question: If our relationship is mutually fulfilling,shouldn’t we trust our partner not to leave us for someone else? It appears so. That
our partner would leave us for someone else—and would leave us despite being in

15Franklin Veaux and Eve Rickert, in their comprehensive guide to non-monogamous life, echo thispoint. See Franklin Veaux and Eve Rickert, More than Two: A Practical Guide to Ethical Polyamory(Portland, OR: Thorntree Press, 2014), p. 317.

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Is Monogamy Morally Permissible?﻿	a mutually fulfilling relationship with us—does not seem like the kind of prospect
toward which it is reasonable to harbor so much fear. By realizing and reflecting on
this, we are likely to loosen the fear’s hold on us.16 (And what if our relationship is
not mutually fulfilling? Then, presumably, it is not worth maintaining in the firstplace. For our partner to leave us for someone she’s happy with would then be something to be welcomed, not feared.)
Admittedly, there are circumstances that make more salient the prospect of yourpartner’s leaving you for someone else. For example, what if your partner discovers
that she would find being with a certain other person even more fulfilling than being
with you, yet this other person lives far away, in someplace you cannot move to? Inorder to be with the other, your partner would have to move away from you. In cases
like this, it might seem that there’s good reason to fear that your partner will leave
you for someone else. It might seem, further, that monogamy would function as akind of protective barrier here; if two partners have decided to restrict themselvesfrom sex and romance with outsiders, then each partner is less likely to discoverthat there is someone else with whom he has better sex, to whom he feels a deeper
romantic connection, or with whom he otherwise gets along better.
Yet there is something puzzling, if not deeply unsettling, in the hope that yourpartner will remain ignorant of options that are better for her. While seeing yourpartner abandon you for another is no doubt painful, consider the nature of the alternative just described: a case in which your partner stays with you only because,
given monogamous restrictions, she has not experienced a certain other person—aperson whom she would in fact be happier with. Is that really that desirable a stateof affairs? Indeed, is it not that state of affairs that we should be more concerned to
avoid here? When leaving us for someone else is the path to a more fulfilling romantic life for our partner, should we not want that for him? However much it may crush
us to see our partner leave us behind in this way, our love and care for her should
lead us to want what’s best for her. Even when it is reasonable, then, to suspect thatour partner will leave us for someone she’s happier with, that is a prospect to be welcomed rather than feared.
To welcome such a prospect might seem to require a high degree of emotional independence from one’s partner—and, indeed, it almost certainly does. By

16

The kind of principle invoked here—that realizing and reflecting on the irrationality of a certain
thought or feeling helps one to overcome it—is among the foundations of some prominent approaches
to psychotherapy, particularly cognitive therapy and rational emotive behavior therapy. See Cory Newman, “Cognitive Restructuring/Cognitive Therapy,” in Christine Nezu and Arthur Nezu, eds., The Oxford
Handbook of Cognitive and Behavioral Therapies (New York, NY: Oxford University Press, 2016), 118141, along with Monica O’Kelly and James Collard, “Rational Emotive Behavior Therapy,” in Christine Nezu and Arthur Nezu, eds., The Oxford Handbook of Cognitive and Behavioral Therapies (NewYork, NY: Oxford University Press, 2016), 142-159. See also Ronald de Sousa, “Love, Jealousy, andCompersion,” in Christopher Grau and Aaron Smuts, eds., The Oxford Handbook of Philosophy of Love
(Oxford, UK: Oxford University Press, 2018), n.p., retrieved from http://www.oxfordhandbooks.com/
view/10.1093/oxfordhb/9780199395729.001.0001/oxfordhb-9780199395729-e-30, for a discussion of
how jealousy can be transmuted into compersion—that is, finding joy rather than anguish in the fact thatone’s partner is enjoying sex or romance with someone else—by modifying the “framing story” in lightof which one interprets one’s feelings.

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H. Chalmers“emotional independence” here I do not at all mean a lack of love or affection, butrather, being comfortable with oneself, satisfied with oneself, secure in oneself. To
be emotionally independent in this sense is to understand that, however much one
treasures one’s relationship, one does not require one’s partner for one to happy;
one could still live a deeply fulfilling life even if one’s partner decided to leave. The
more one attains this kind of emotional independence and maturity, the less one islikely to suffer from the insecurity that lies at the core of jealousy.17 As ever, themost genuine security comes from within. Just as one should be prepared to face life
should one’s partner die, one should be prepared to face life should one’s partner
decide to leave.
Abandoning monogamy, recognizing the irrationality of jealousy, and cultivating emotional independence are together a foundation for overcoming jealousy.
Of course, they do not guarantee that one will never feel jealous at all. Many nonmonogamous relationships involve occasional moments of jealousy. But then, many
non-monogamous relationships have likewise been the site of partners’ discovering
powerful ways of coping with and working through their jealousy.18 Such experiences suggest that jealousy is not something to which partners in a non-monogamous relationship must resign themselves. Rather, when partners in a non-monogamous relationship find themselves feeling jealous, they can simply accept it as achallenge to be managed constructively, much like other challenges that arise inrelationships.

3 Conclusion
With that I conclude my responses to what are, in my view, the most prominent
defenses of monogamy. If my responses are on the mark, these defenses all fail. Of
course, there are other, less well-known defenses.19 Regrettably, I cannot respond tothem here. And even if these further defenses likewise fail, there remains the possibility that newer, better defenses of monogamy will arise. Still, given the apparent
failure of what might have seemed its flagship defenses, monogamy is in a bad way.
Unless some other defense turns out to succeed where its more prominent forerunners have failed, monogamous restrictions will, by all indications, be analogous tothe morally troubling restriction on having additional friends. Thus, while the case17
On this point, see Peter Salovey and Judith Rodin, “Coping with Envy and Jealousy,” Journal ofSocial and Clinical Psychology, Vol. 7, No. 1, (1988), 15-33, together with Peter Salovey and Judith
Rodin, “Provoking Jealousy and Envy: Domain Relevance and Self-Esteem Threat,” Journal of Social
and Clinical Psychology, Vol. 10, No. 4, (1991), 395-413, who find that higher self-reliance and selfesteem are associated with lower levels of jealousy. See also Laura Guerrero, “Attachment-Style Differences in the Experience and Expression of Romantic Jealousy,” Personal Relationships, Vol. 5, (1998),
273-291.
18
See Dossie Easton and Janet Hardy, The Ethical Slut: A Practical Guide to Polyamory, Open Relationships, and Other Adventures ­(2nd ed.) (Berkeley, CA: Celestial Arts, 2009), ch. 13, along with Veaux
and Rickert (op. cit., ch. 8). As these discussions show, one theme in dealing with jealousy is the importance of maintaining communication. When partners know that they can voice their feelings to one
another and be accepted and understood, jealousy has less of a chance to smolder.
19
See, for example, Weaver and Woollard (op. cit., pp. 515-519).

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Is Monogamy Morally Permissible?﻿	

I’ve advanced against monogamy is not conclusive, it is, at the very least, suggestive. However far the matter remains from being settled, the evidence thus far points
largely in one direction: We morally ought to reject monogamy. Just as one morally
ought to allow one’s partner to have additional friends, one morally ought to allow
one’s partner to have additional partners.
A few final clarifications are called for. First, in suggesting that non-monogamy ismorally required, I’m not suggesting that partners have no right to be monogamous.
That is, I’m not suggesting that partners ought to be coercively prevented fromholding one another to monogamous restrictions (whatever such coercive prevention would mean in practice). Even if a certain restriction is immoral, partners could
still—and, I believe, often or typically do—have the right to hold one another to it.
This, at any rate, is what I take the case to be with monogamy. Partners indeed havethe right to be monogamous, though that does not suffice to make monogamy right.
Second, at this point some might feel a lingering worry: Isn’t non-monogamy aradical lifestyle change? Could people really be expected to abandon so much ofwhat is familiar to their romantic life? In fact, however, non-monogamy need notpose as radical a lifestyle shift as it might seem. Contrary to what people often
assume, being non-monogamous does not mean that one must maintain multiple
relationships at a time. After all, one can be non-monogamous and in a relationshipwith only one person at a certain time—for example, in a case in which one simply hasn’t found others in whom one is interested. For that matter, one can even be
non-monogamous while single, just as one can be monogamous while single. Whatbeing non-monogamous means, rather, is simply that one is open to having multiple
relationships at a time—open in the sense of rejecting restrictions thereon—both foroneself and whatever partners one might have.
Thus, even if you have little desire to pursue multiple relationships at a time, you
can live accordingly while remaining non-monogamous. You can stick to relationships with only one person at a time; the key is simply that you remain open to yourpartner’s having multiple relationships at a time, should she desire it. Now, if yourpartner likewise has no interest in pursuing multiple relationships at a time, thenyour relationship with him will, from a certain distance, appear no different froma typical, monogamous relationship. Crucially, though, in being non-monogamous,
you and your partner would both remain open to having multiple relationships at atime. That is, you and your partner would recognize that if either of you does cometo desire an additional relationship, neither of you will in principle stand opposed topursuing it. It is this openness, rather than the actual state of being in multiple relationships at a time, that is the essence of non-monogamy.20

20
Thanks to [Zach Barnett, Tobias Fuchs, Hollie Lohman, and several anonymous referees] for helpfulcomments and discussion.

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