A public notary in Brazil has registered a three-person partnership as a legally recognized civil union . Brazilians are waiting to see how other public officials treat the notary’s action.

The notary, Claudia do Nascimento Domingues, who serves the city of Tupa, “said the move reflected the fact that the idea of a ‘family’ had changed. ‘We are only recognising what has always existed. We are not inventing anything. For better or worse, it doesn’t matter, but what we considered a family before isn’t necessarily what we would consider a family today’.”

Now, the reason of principle that intimate partnerships of three or more persons cannot truly be marriages, and should not be legally recognized as marriages or the equivalent, is . . . Well, remind me again, what is it?

Of course, the reason is fairly clear for those (I’m one) who understand marriage as a conjugal partnershp, i.e., a multi-level (and in that sense comprehensive) union of husband and wife founded on the biological (“one-flesh”) communion made possible by the sexual-reproductive complementarity of spouses. For an explanation and defense, see here ; for a more detailed statement of the case, and response to critics, see the forthcomng book by the same authors under the same title.) But what is the reason for those who propose to ditch the conjugal understanding of marriage and replace it with a conception of marriage as sexual-romantic domestic partnership (what one opponent of the conjugal conception describes as your relationship “with your Number One Person”)?

To be sure, there are those (such as the three hundred plus self-described “lesbian, gay, bisexual, transgender and allied activists, scholars, educators, writers, artists, lawyers, journalists, and community organizers,” including such notables as Gloria Steinem, Barbara Ehrenreich, and Kenji Yoshino), who have already signed on (quite literally) to the proposition that there are no reasons of principle (or valid reasons of any kind) for conceiving marriage or the equivalent as a two-person relationship, as opposed to a relationship of three or more individuals (triads, quadrads, etc.) in a polyamorous sexual partnership. (See the manifesto ” Beyond Same-Sex Marriage ,” expressly demanding legal recognition of, among other things, “committed, loving households in which there is more than one conjugal partner.”)

But what is the reason of principle that can be given by those who, while rejecting the idea that sexual-reproductive complementarity is an essential element of marriage, do not—-or do not yet —-wish to give up the idea of marriage as the sexually exclusive union of two, and not more than two, persons? Is there a reason of principle? Or is the belief in “two-ness” mere bigotry?