Of course, some people are quick to make that argument today — like Fredrik deBoer, who writes in Politico:
Now that we’ve defined that love and devotion and family isn’t driven by gender alone, why should it be limited to just two individuals? The most natural advance next for marriage lies in legalized polygamy . . . .Well, I'm sorry, deBoer, but you're missing something. Oh, I admit your argument has a certain appeal on the surface: how can we say a policy that excluded people from the institution of marriage based on their gender or sexual orientation was unconstitutional discrimination, without saying the same thing of a policy that excludes people based on their number? If it doesn't matter whether you're male or female, straight or gay, then how can it matter whether you're 2, 3, 5, 10, or 50 people?
In Chief Justice John Roberts’ dissenting opinion, he remarks, “It is striking how much of the majority’s reasoning would apply with equal force to the claim of a fundamental right to plural marriage.” As is often the case with critics of polygamy, he neglects to mention why this is a fate to be feared. . . .
[P]rogressives who reject the case for legal polygamy often don’t really appear to have their hearts in it. They seem uncomfortable voicing their objections, clearly unused to being in the position of rejecting the appeals of those who would codify non-traditional relationships in law. They are, without exception, accepting of the right of consenting adults to engage in whatever sexual and romantic relationships they choose, but oppose the formal, legal recognition of those relationships. They’re trapped, I suspect, in prior opposition that they voiced from a standpoint of political pragmatism in order to advance the cause of gay marriage.
In doing so, they do real harm to real people. Marriage is not just a formal codification of informal relationships. It’s also a defensive system designed to protect the interests of people whose material, economic and emotional security depends on the marriage in question. If my liberal friends recognize the legitimacy of free people who choose to form romantic partnerships with multiple partners, how can they deny them the right to the legal protections marriage affords?
Polyamory is a fact. People are living in group relationships today. The question is not whether they will continue on in those relationships. The question is whether we will grant to them the same basic recognition we grant to other adults: that love makes marriage, and that the right to marry is exactly that, a right. . . .
Conventional arguments against polygamy fall apart with even a little examination. Appeals to traditional marriage, and the notion that child rearing is the only legitimate justification of legal marriage, have now, I hope, been exposed and discarded by all progressive people. What’s left is a series of jerry-rigged arguments that reflect no coherent moral vision of what marriage is for, and which frequently function as criticisms of traditional marriage as well.
But polygamy is significantly different — even assuming for the sake of argument that we have no concerns about coercion or power disparities within any given polygamous relationship. As my mom, Ann Althouse, explained 9 years ago:
Legal marriage isn't just about love, it's an economic arrangement. Having the state authorize your union is not the same thing as having your friends and neighbors approve of you and your religious leaders bless you. It affects taxes and employee benefits -- huge amounts of money. A gay person with a pension and a health insurance plan is incapable of extending those benefits to his (or her) partner. He (or she) can't file a joint tax return. That's not fair. A polygamous marriage, however, puts a group of persons in a position to claim more economic benefits than the traditional heterosexual couple. That doesn't appeal to our sense of fairness.UPDATE: My mom sees a problem with her own argument from 9 years ago, in light of the majority's reasoning in Obergefell.
The law doesn't assess how much two people love each other. Two persons of opposite sexes can marry for all sorts of reasons. If there were a device that could look into their souls and measure their love, we wouldn't accept the outrageous invasion of privacy it would take for the government to use it. Excluding gay couples from marrying does generate the complaint that society does not sufficiently respect homosexual love, and by harping on this point, proponents of gay marriage activate their opponents who think that's a good thing.
But it's not all about love and who respects what. It's also about economics. And in that dimension, it's easy to distinguish polygamy.
ADDED: Judge Richard Posner points out another important distinction:
[P]olygamy imposes real costs, by reducing the number of marriageable women. Suppose a society contains 100 men and 100 women, but the five wealthiest men have a total of 50 wives. That leaves 95 men to compete for only 50 marriageable women.MORE: Jonathan Rauch observes:
[T]he case for gay marriage is the case against polygamy, and the public will be smart enough to understand the difference.UPDATE: My mom responds to those quotes by Posner and Rauch:
Gay marriage is about extending the opportunity to marry to people who lack it; polygamy, in practice, is about exactly the opposite: withdrawing marriage opportunity from people who now have it. Gay marriage succeeded because no one could identify any plausible channels through which it might damage heterosexual marriage; with polygamy, the worries are many, the history clear, and the channels well understood.
I've got a problem with that! Talk about a male perspective! What about the women who want to choose to share one man? They should be denied to preserve a pool of marriageable women for all the extra males that would otherwise have scarce pickings? Are women some kind of natural resource to be conserved for the benefit of males?UPDATE: Jonathan Rauch expands on his argument against polygamy.
As the old saying goes: Feminism is the radical notion that women are people. If women think they are better off as multiple wives to one high-quality male, why should they be cut off from that way of life so that some less-desired male will have better odds of getting a woman for himself? Is this everybody-gets-just-one theory of marriage some kind of welfare program for undesirable males?
I can see that society fears its renegade young male and would like to tame them through marriage, leveraging the power of their sexuality lest they expend that energy in acts of violence and dissolution. I can see the idea of using women for this purpose and rejecting polygamy because it takes women out of commission in that service. . . . But if you use that as your overt argument, you're going to run up against ideas about women's autonomy and freedom. We're not society's tools.