It was only yesterday, was it not, that we were being assured that the redefinition of marriage to include same-sex partnerships would have no impact on persons and institutions that hold to the traditional view of marriage as a conjugal union? Such persons and institutions would simply be untouched by the change. It won’t affect your marriage or your life, we were told, if the law recognizes Henry and Herman or Sally and Sheila as “married.”

Those offering these assurances were also claiming that the redefinition of marriage would have no impact on the public understanding of marriage as a monogamous and sexually exclusive partnership. No one, they insisted, wanted to alter those traditional marital norms. On the contrary, the redefinition of marriage would promote and spread those norms more broadly.

When some of us warned that all of this was nonsense, and pointed out the myriad ways that Catholics, Evangelicals, Mormons, Eastern Orthodox Christians, Orthodox Jews, Muslims, and others would be affected, and their opportunities and liberties restricted, the proponents of marriage redefinition accused us of “fearmongering.” When we observed that reducing marriage to a merely emotional union (which is what happens when sexual reproductive complementarity is banished from the definition) removes all principled grounds for understanding marriage as a sexually exclusive and faithful union of two persons, and not an “open” partnership or a relationship of three or more persons in a polyamorous sexual ensemble, we were charged with invalid slippery-slope reasoning. Remember?

No one, they assured us, would require Catholic or other foster care and adoption services to place children in same-sex headed households. No one, they said, would require religiously affiliated schools and social-service agencies to treat same-sex partners as spouses, or impose penalties or disabilities on those that dissent. No one would be fired from his or her job (or suffer employment discrimination) for voicing support for conjugal marriage or criticizing same-sex sexual conduct and relationships. And no one was proposing to recognize polyamorous relationships or normalize “open marriages,” nor would redefinition undermine the norms of sexual exclusivity and monogamy in theory or practice.

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That was then; this is now.

I must say, though, that I still can’t fathom why anybody believed any of it—even then. The whole argument was and is that the idea of marriage as the union of husband and wife lacks a rational basis and amounts to nothing more than “bigotry.” Therefore, no reasonable person of goodwill can dissent from the liberal position on sex and marriage, any more than a reasonable person of goodwill could support racial segregation and subordination. And this, because marriage, according to the redefiners, consists principally of the emotional union of people committed to mutual affection and care. Any distinctions beyond this one they condemn as baseless.

Since most liberals and even some conservatives, it seems, apparently have no understanding at all of the conjugal conception of marriage as a one-flesh union—not even enough of a grasp to consciously consider and reject it—they uncritically conceive marriage as sexual-romantic domestic partnership, as if it just couldn’t possibly be anything else. This is despite the fact that the conjugal conception has historically been embodied in our marriage laws, and explains their content (not just the requirement of spousal sexual complementarity, but also rules concerning consummation and annulability, norms of monogamy and sexual exclusivity, and the pledge of permanence of commitment) in ways that the sexual-romantic domestic partnership conception simply cannot. Still, having adopted the sexual-romantic domestic partnership idea, and seeing no alternative possible conception of marriage, they assume—and it is just that, an assumption, and a gratuitous one—that no actual reason exists for regarding sexual reproductive complementarity as integral to marriage. After all, two men or two women can have a romantic interest in each other, live together in a sexual partnership, care for each other, and so forth. So why can’t they be married? Those who think otherwise, having no rational basis, discriminate invidiously. By the same token, if two men or two women can be married, why can’t three or more people, irrespective of sex, in polyamorous “triads,” “quadrads,” etc.? Since no reason supports the idea of marriage as a male-female union or a partnership of two persons and not more, the motive of those insisting on these other “traditional” norms must also be a dark and irrational one.

Thus, advocates of redefinition are increasingly open in saying that they do not see these disputes about sex and marriage as honest disagreements among reasonable people of goodwill. They are, rather, battles between the forces of reason, enlightenment, and equality—those who would “expand the circle of inclusion”—on one side, and those of ignorance, bigotry, and discrimination—those who would exclude people out of “animus”—on the other. The “excluders” are to be treated just as racists are treated—since they are the equivalent of racists. Of course, we (in the United States, at least) don’t put racists in jail for expressing their opinions—we respect the First Amendment; but we don’t hesitate to stigmatize them and impose various forms of social and even civil disability upon them and their institutions. In the name of “marriage equality” and “non-discrimination,” liberty—especially religious liberty and the liberty of conscience—and genuine equality are undermined.

The fundamental error made by some supporters of conjugal marriage was and is, I believe, to imagine that a grand bargain could be struck with their opponents: “We will accept the legal redefinition of marriage; you will respect our right to act on our consciences without penalty, discrimination, or civil disabilities of any type. Same-sex partners will get marriage licenses, but no one will be forced for any reason to recognize those marriages or suffer discrimination or disabilities for declining to recognize them.” There was never any hope of such a bargain being accepted. Perhaps parts of such a bargain would be accepted by liberal forces temporarily for strategic or tactical reasons, as part of the political project of getting marriage redefined; but guarantees of religious liberty and non-discrimination for people who cannot in conscience accept same-sex marriage could then be eroded and eventually removed. After all, “full equality” requires that no quarter be given to the “bigots” who want to engage in “discrimination” (people with a “separate but equal” mindset) in the name of their retrograde religious beliefs. “Dignitarian” harm must be opposed as resolutely as more palpable forms of harm.

As legal scholar Robert Vischer has observed, “The tension between religious liberty and gay rights is a thorny problem that will continue to crop up in our policy debates for the foreseeable future. Dismissing religious liberty concerns as the progeny of a ‘separate but equal’ mindset does not bode well for the future course of those debates.” But there is, in my opinion, no chance—no chance—of persuading champions of sexual liberation (and it should be clear by now that this is the cause they serve), that they should respect, or permit the law to respect, the conscience rights of those with whom they disagree. Look at it from their point of view: Why should we permit “full equality” to be trumped by bigotry? Why should we respect religions and religious institutions that are “incubators of homophobia”? Bigotry, religiously based or not, must be smashed and eradicated. The law should certainly not give it recognition or lend it any standing or dignity.

The lesson, it seems to me, for those of us who believe that the conjugal conception of marriage is true and good, and who wish to protect the rights of our faithful and of our institutions to honor that belief in carrying out their vocations and missions, is that there is no alternative to winning the battle in the public square over the legal definition of marriage. The “grand bargain” is an illusion we should dismiss from our minds.

Of course, with sexual liberalism now so powerfully entrenched in the established institutions of the elite sector of our culture (and, let us not kid ourselves, fully embraced by the President of the United States and the leadership of the Democratic Party), some view the defense of marriage as a lost cause. I think that is another mistake—one that sexual liberals have every reason to encourage their opponents to make, and ample resources to promote. We’ve all heard the argument (or taunt): “The acceptance of same-sex marriage on a national scale is inevitable. It’s a done deal. You had better get on the right side of history, lest you be remembered in the company of Orval Faubus.”

Of course, this is what we were told about a “woman’s right” to abortion in the mid-’70s. But it didn’t turn out that way. A greater percentage of Americans are pro-life today than in the 1970s, and young people are more pro-life than people of their parents’ generation. The idea promoted by the abortion lobby when their cause seemed to be a juggernaut—that “the American people will inevitably accept abortion as a matter of women’s rights and social hygiene”—proved spectacularly false.

Or, speaking of “social hygiene,” think back to the 1920s and ’30s when eugenics was embraced by the elite institutions of American society—from the wealthy philanthropic foundations, to the mainline Protestant denominations, to the Supreme Court of the United States. Affluent, sophisticated, “right-minded” people were all on board with the eugenics program. It, too, seemed like a juggernaut. Only those retrograde Catholics, joined by some other backward religious folk, resisted; and the thought was that the back of their resistance would soon be broken by the sheer rationality of the eugenics idea. The eugenicists were certain that their adversaries were on “the wrong side of history.” The full acceptance of eugenics was “inevitable.” But, of course, things didn’t quite turn out that way.

Note that my point here is not to say or imply that redefining marriage is morally equivalent to abortion or eugenics. There are obvious and important differences. My point is about the claim by progressives and some others in each case that the triumph of the cause was “inevitable,” and that those who declined to go along were “against progress” and had placed themselves on the “wrong side of history.”

Does that mean that the reverse is true, that the conjugal conception of marriage will inevitably prevail in law and culture? No. There is nothing inevitable in this domain. As the left-wing—but anti-Hegelian—Brazilian legal theorist Roberto Unger used to preach to us in courses at Harvard Law School, the future will be the fruit of human deliberation, judgment, and choice; it is not subject to fixed laws of history and forces of social determinism. As the Marxists learned the hard way, the reality of human freedom is the permanent foiler of “inevitability” theses. Same-sex marriage and the assaults on liberty and equality that follow in its wake are “inevitable” only if defenders of marriage make their adversaries’ prophecies self-fulfilling ones, by buying into them.

An earlier version of this essay appeared on Mirror of Justice.