William Saletan of Slate thinks that polyamorous marriage doesn’t follow from gay marriage. He lists five reasons for why he thinks this is so:

1. Immutability. Kennedy tosses this into his opinion, bizarrely, as a side comment. Referring to gays who seek matrimony, he says, “[T]heir immutable nature dictates that same-sex marriage is their only real path to this profound commitment.” Later, he speaks of “new insights” that have transformed society, including this one: “Only in more recent years have psychiatrists and others recognized that sexual orientation is both a normal expression of human sexuality and immutable.” Kennedy doesn’t elaborate on these remarks, but they’re huge. Immutability is the biggest difference between homosexuality and polyamory. Even the pro-polyamory law review article cited by Roberts in his dissent acknowledges that immutability is a crucial factor in identifying unjust discrimination against classes of people—and that “polygamists are not born that way.”

He is saying here that homosexuality, unlike polyamory, is immutable, and hence non-analogous to polyamory. His argument goes something like this: one is born gay and remains so throughout life, but one isn’t born polyamorous, and nor is one biologically compelled to remain so throughout life.

Not so fast.

If gender is fluid, then sexual orientation is not immutable. Here is why:

Caitlyn Jenner was born a man and was a heterosexual for the majority of her life, but then she became a woman who is sexually attracted to other women, and hence her sexual orientation became homosexual. Since her sexual orientation changed from heterosexual to homosexual, it is by definition mutable.

“2. Loneliness. According to Kennedy, “Marriage responds to the universal fear that a lonely person might call out only to find no one there. It offers the hope of companionship and understanding and assurance that while both still live there will be someone to care for the other.” At the end of his opinion, Kennedy returns to this theme. He says gay people who are legally excluded from marriage are “condemned to live in loneliness.” You can’t say that about polyamorists. Legally, they may be condemned to monogamy. But not to solitude.”

No, they’re not. There is nothing stopping two gays from living with one another. Moreover, conservatives were willing to grant gay couples all of the rights and privileges granted to heterosexual couples (the so called civil union), and so it’s not the case that “material circumstances” unconducive to coupling and brought about by a lack of state privileges and rights were preventing gays from living as a couple.

3.Exclusion. Kennedy notes that when laws forbid gay marriage, “same-sex couples are denied all the benefits afforded to opposite-sex couples.” He lists many such benefits, including tax breaks, inheritance rights, property rights, adoption rights, hospital visitation, survivor benefits, and health insurance. He also points out that children in same-sex households “suffer the significant material costs of being raised by unmarried parents.” That’s not true for kids in polyamorous households. Their parents can marry—they just have to pair up, leaving one adult, at most, unaccounted for. And when they do, each couple gets the same spousal benefits as a monogamous couple.

And it’s not true of “gay couples” either, because conservatives were willing to grant gays “civil unions”, which gave gays all of the rights and privileges that come with marriage bar the word marriage itself.

4. Divided loyalty. Kennedy says marriage “embodies the highest ideals of love, fidelity, devotion, sacrifice, and family.” He doesn’t explain how these ideals distinguish homosexuality from polygamy. But they do. Fidelity and devotion are concentrated virtues. When you spread them out among multiple spouses (or, yes, even among children—that means you, Duggars), you dilute them. One article cited by Roberts notes that many polyamorists are “polyfidelitous,” which means they “don’t date outside their ménage.” But when you’re free to have sex with anyone inside the ménage, or to spend the weekend with this spouse instead of that one, the value of your fidelity and devotion are diminished, just as surely as inflation shrinks the value of a dollar.

This argument doesn’t work because it doesn’t work in all cases. A married, homosexual couple might not love one another as much as each member of a polyamours relationship loves one another, so does that mean that the said married, homosexual couples ought not have been able to marry? If you think I’m being pedantic, then consider this: conservatives used to argue that marriage is about children, to which pedantic leftists responded by pointing out that not all married, heterosexual couples have children. In the same way, not all married, homosexual couples love one another as much as members of a polyamours relationship love one another.

5. Conflict. Countless marriages have exploded and ended because two spouses couldn’t get along. With three or four spouses, it’s that much harder to keep everyone happy. Kennedy doesn’t talk about this, but Mary Bonauto, an attorney representing gay couples in Obergefell, discussed it during oral argument. When Alito asked her why states should have to recognize gay marriages but not plural marriages—and forced her to address the scenario of two men and two women in a foursome, which bypasses the usual complaint about underage or patriarchal polygamy—Bonauto replied that plural marriage might raise valid governmental concerns about “disrupting family relationships.” For example, she asked: “If there’s a divorce from the second wife, does that mean the fourth wife has access to the child of the second wife?”

Conflict isn’t unique to polyamarous marriage. One could say that, on average, it’s greater in polyamous marriages than in homosexual or heterosexual marriages, but then again, one could say that marriage is about children, and since, on average, heterosexual couples have more children than homosexual couples, homosexuals should not be able to marry. No leftist would accept that argument, so why should conservatives accept it with “conflict” substituted for “children”?