The normal arguments go like this:
Conservative: Gay “marriage” denigrates the traditional, irreducible construct of marriage. If we allow gay “marriage,” then what’s next? Three people will want to get “married,” or six people and two goats, or a man and his television.
Liberal: That’s ridiculous. You are advancing preposterous scenarios in an effort to win an argument over a legitimate issue. Everyone knows that gay “marriages” have the same features as straight marriages: two committed spouses caring for each other, raising children, and committing to each other for life.
I can’t think of any other issue on which societal opinion has moved so rapidly from a seemingly time-tested viewpoint to a radically different one as gay “marriage.” And, unfortunately, the results have not been pretty—those who fear the destruction of traditional marriage have had plenty to substantiate their worries.
For example, a recent advice column in Slate, which I had to pay close attention to because I first assumed that it was a parody, mentions identical-twin brothers who can finally remove the secrecy surrounding their incest because “we live in a state where same-sex marriage is legal, so we’re getting pressure to settle down.” There are more and more stories like this—various “non-traditional,” even morally repugnant, relationships seeing a ray of light pointing towards legitimacy.
I actually am not really bothered by gay “marriage”; I would prefer that government not be in the business of trying to define, regulate, or intervene at all in any relationship among consenting adults.