In an essay in today's edition of his blog Dappled Things the Ordinarily Straight-Thinking Occasionally Pipe-Smoking Jim Tucker complains about homemade wedding vows in which putative couples deliberately leave out any reference to their pairing lasting "'till death do us part", and he's not angry merely because of the further paring down of Hopkinsesque language in our rituals. What irks him is that nobody is complaining about this sort of thing the way they complain about civil "unions" between homosexual couples. He says that it is "inconsistent" to protest the one but not the other. His reasoning appears to be that, since folks who protest civil unions for homosexual couples do so on moral grounds, then anyone who has any objection to any other kind of pairing on moral grounds ought to protest as loudly.
But that doesn't follow at all, and for two reasons. The first is merely practical. It may be that I do not approve of "marriages" in which the couples have no intention of staying together forever, but that's not to say that I find that kind of arrangement as worrisome as other possible arrangements. To say that all morally dubious arrangements ought to be protested with equal vigor would entail that we protest unjust parking tickets with the same vehemence that we protest abortion. Both are cases of injustice, after all. Or, in a more realistic example, it is to say that we ought to invade North Korea and bring down its government, because that's what we did in Afghanistan and Iraq.
The second reason why Tucker's argument won't work is more philosophical. The reason why conservatives are opposed to civil unions among homosexual couples has nothing to do with the moral status of the proposed union. Not all conservatives agree that such unions are, in fact, immoral. What all, or at least most, conservatives would agree on is that the government has no reason to involve itself in legislation--either pro or con--regarding friendships between private citizens. This means that, in fact, the government not only has no business "recognizing" civil unions between homosexual couples, it doesn't really have any business recognizing unions between heterosexual couples either. Marriage, in a perfect world, would be entirely within the domain of the Church. The fact that most governments do recognize heterosexual unions has nothing to do with morality and everything to do with protecting the interests of the state: it is in the state's interest to see to it that its population does not dwindle to zero. For that reason it provides incentives, in the form of various government-sponsored perks, for heterosexual unions. The value of these unions is independent of how long they last, just so long as they are more likely than not to produce offspring. Civil unions between homosexual couples cannot produce new life, even in principle, so no state has any particular interest in promoting such unions.
Catholics, as a matter of doctrine, must oppose civil and private unions between homosexual and heterosexual couples if those unions violate either the divine or the natural law, as both would if there were any sexual relations outside of the Sacrament of Matrimony. In this regard everyone is treated equally. The difficulty, of course, lies in the fact that homosexuals have no particular inclination to have sex with folks of the opposite sex, and so they are not inclined to enter into the Sacrament of Matrimony. What they tend to want is recognition of the love they feel for their partners, on the one hand, and some sort of share in the government-sponsored perks of heterosexual marriage on the other. There's no compelling reason to think that it is inconsistent to think that civil unions of the homosexual kind could lead to the recognition of all sorts of bizarre things being granted government-sponsored perks while thinking that those of the heterosexual kind are less likely to have that effect.