Slovak translation here 
I was surprised to learn that most moderate opponents of same-sex marriage have no problem with the idea of “domestic partnerships,” which give homosexual couples many of the legal benefits of marriage. Their thinking is: “If two homosexuals wish to share their lives and fortunes and take care of one another in sickness and old age, why shouldn’t they have the legal benefits that straight couples enjoy? Just don’t call it ‘marriage.'”
It seems a sensible compromise, unless, of course, one simply hates homosexuals and wants them to suffer.
Why not call it “marriage”? Because of a deep conviction that marriage is a more serious institution, because it provides the best framework for begetting and nurturing the next generation. Therefore, marriage should enjoy a higher dignity and status than mere domestic partnership.
Gay marriage advocates have a ready reply to this: straight people who cannot have children, or who choose not to have children, are allowed to marry. So marriage is not about reproduction.
There is no real reply to this argument. Yes, some anti-natal couples may change their minds and choose to have children. But that is not possible for sterile couples, who still can marry.
Gay marriage advocates also point out that sterile straight couples can still have families by adopting children or using surrogate parenting — and so can homosexual couples, which opens a whole new can of worms.
One can argue that homosexual couples are not optimal for the psychological development of children, which would be better served by parents of both sexes. But proponents of gay adoption could grant that argument and still retort that even suboptimal parents can give children better care than the staff of an orphanage — many of which, by the way, are staffed by people of only one sex, particulaly those run by religious orders, which are not exactly magnets for red-blooded heterosexuals either.
Homosexual marriage advocates demand marriage equality on the grounds that their couplings are not relevantly different from straight marriages, as long as sterile straights are allowed to marry for companionship, and to have families through adoption or surrogacy.
This argument cannot be dismissed as an example of modern one-size-fits-all egalitarianism run amok. For even Aristotle defined justice as treating equal cases equally — and if sterile straight couples can marry, then why not sterile homosexual couples? And if sterile straights can have families through adoption and surrogacy, then why not sterile gays? Why should homosexuals accept second-class status?
It strikes me that the only way to preserve marriage as an exclusively heterosexual institution is to deal squarely with the issue of straight people who cannot or will not reproduce. In the past, when the causes of sterility were poorly understood, it was always possible to believe that a miracle baby would come along. Furthermore, shorter life spans and higher standards of taste and dignity prevented marriages between people who are simply too old to conceive. Finally, the facts that celibacy leaves a lot to be desired and that birth control was unreliable made it very unlikely that fertile couples would never produce children, even if they did not want them. Thus it made sense to think of marriage as simply the union of heterosexuals — the kind of people who, prima facie, can produce children — and just treat the instances where that did not happen as negligible. Marry ’em all, and let God sort it out.
But modern medicine has changed everything. Today, when effective birth control (including sterilization) is widely available and fertile couples can confidently avoid conception; when individuals can know for certain that they are irreversibly sterile; and when men and women routinely live long beyond when they can have children, one has to ask: Is gay marriage any more a mockery of the institution than two octogenerians pushing their walkers down the aisle to tie the knot? Is marriage between homosexuals any more a mockery than marriage between straights who cannot or will nor have children, even through adoption or surrogacy, either from medical misfortunes or simply out of selfishness, hedonism, and immaturity?
If the opponents of homosexual marriage are willing to accept a “second class” institution — domestic partnership — for infertile couplings, then why not extend that to straight couples who cannot and will not reproduce? Indeed, why not make “second class marriage” the default status for all married couples, granting first class status only upon the birth or adoption of the first child?
Of course we are talking about legal marriages here, marriages recognized by the state. People are — and would remain — free to celebrate religious or spiritual marriages of their own design and definition. But the state need not recognize all of them.
In such a system, the existence of homosexual marriage would be entirely contingent on whether it is deemed desirable to allow homosexual couples to adopt children, avail themselves of surrogacy, or raise the children of one partner’s previous marriage. None of these arrangements strike me as optimal conditions for raising children if heterosexual alternatives are available.
Exploring the idea of limiting marriage only to couples who have children, while reserving domestic partnership for the rest, has benefits far beyond reframing the debate about homosexual marriage, which is a minor issue compared to the demographic and cultural problems caused by the decline of heterosexual marriage and the heterosexual family.
Even if homosexual marriage were not an issue, the distinction between marriage and domestic partnership allows us to refocus and recenter the institution of marriage on the sole function by which it merits special social and legal status: the procreation and nurture of the next generation. Such an arrangement would uphold the heteronormativity and reproductive purpose of marriage while giving options to those who fall short.