Ian Harris argues the focus should not be on the scope of the words "marriage" and "civil union"but rather the substance of relationships.
If a rose by any other name would smell as sweet, why doesn't "civil union" for a committed partnership smell as sweet as "marriage"?
After all, couples in a civil union are wed in all but word.
In ordinary usage, however, the two terms recognise a fundamental difference between the relationship of a man and a woman, and one between two men or two women - and what's wrong with acknowledging that?
The current call by some same-sex couples to allow "marriage" to apply to them therefore seems to me to be seeking change but not difference.
They have made their commitment to each other publicly and with legal effect. With one proviso, it seems unnecessary to press for a change that would leave them exactly where they are now.
Far more useful would be opening up a discussion on the quality of every relationship, heterosexual or homosexual, and on what makes for loving long-term partnerships.
The proviso relates to adoption.
Homosexual partners are not permitted to adopt a child. Remove that barrier - and research shows children with same-sex parents fare pretty much the same as those with male-female parents - and the last trace of statutory discrimination goes with it.
However, a comment by US President Obama that he supports legalising gay marriage has spurred Labour MP Louisa Wall to draft a Bill that would redefine marriage to apply to any couple who have formally committed themselves to one another.
Sure, there are some same-sex partners who would like to be known as married rather than couples in a civil union. For heterosexual couples, the word is important because in every culture and every age it has described the union of a man and a woman, and they see no good reason to change that now. Most use the word "marriage" not as a way to express superiority or to judge others, but because it is precise and makes sense.
Homosexuals have not always been so enamoured of marriage. In 1969, the Gay Liberation Front in New York declared: "We expose the institution of marriage as one of the insidious and basic sustainers of the system. The family is the microcosm of oppression."
Twenty years later Paula Ettelbrick, a professor of law and women's studies, wrote: "Marriage runs contrary to two of the primary goals of the lesbian and gay movement: the affirmation of gay identity and culture and the validation of many forms of relationships."
Twenty years on again and there has been a sea change. American homosexuals are now campaigning for "marriage equality" as a basic human right. Adding to a puzzling mix, a poster at a recent demonstration declared: "Attention heterosexuals: We want to be miserable too!"
Yet the term "civil union" does not denote second-class citizens in a B-grade partnership, as the advocates of change suggest. It implies no lack of respect for those involved - some civil unions are heterosexual anyway.
It is unfortunate that the focus is the scope of the word "marriage", not the substance of the relationships, which is beyond anything the law can prescribe.
That, however, is the very area where discussion could prove most productive, and where same-sex and man-woman pairings might learn from each other.
What, for example, makes a good marriage?
A good civil union?
The answer lies not in whether they carry the label "marriage", but what each partner brings to their relationship.
American scholar of myth Joseph Campbell saw a mythic depth in marriage. When two people find their proper counterpart, he said, they develop a spiritual identity: the two become one. That involves sacrifice, a word meaning "making sacred".
"If marriage is only a love affair it will end in disappointment," he said.
"It's an ordeal, and the ordeal is the sacrifice of ego to a relationship in which two have become one. You're sacrificing not to each other but to unity in a relationship.
"The Chinese image of the Tao, with the dark and light interacting - that's the relationship of yin and yang, male and female, which is what marriage is. You're no longer this one alone, your identity is in a relationship."
Mythically, that involves "the sacrifice of the visible entity for a transcendent good ... By marrying the right person we reconstruct the image of the incarnate God [Godness enfleshed in the human], and that's what marriage is."
What Prof Campbell is pointing to could, of course, apply to people in traditional marriages and in civil unions - or not. The labels are secondary.
• Ian Harris is a journalist and commentator.
