Even then, marriage had attributes that traditionalists would like to forget. Husbands who forced themselves on their wives were not guilty of rape, since they were legally entitled to sexual access. Contraception was forbidden in many states. Only in 1965 did the Supreme Court decide that such laws "violate the right of marital privacy."
The ideal of marriage enshrined in the 1950s reflects a myopic nostalgia for a phase that didn't last. The 1960s brought no-fault divorce, which allowed wives as well as husbands to dissolve their bonds without proving some terrible transgression by the spouse.
This was an earthquake, causing unprecedented numbers of unions to collapse. A writer for the conservative Family Research Council said that under no-fault divorce laws, marriage became "nothing more than notarized dating." Maggie Gallagher of the National Organization for Marriage said their effect was nothing less than "the abolition of marriage."
In a sense, she's right. But you don't see many conservatives trying to repeal no-fault laws in the name of "traditional marriage." Gallagher misses the more fundamental point: This institution is not something passed down unaltered from generation to generation, like the family silver. It is continually in flux, taking forms that would surprise our forebears.
Marriage, like transportation, has always been a part of human existence. But riding a donkey is very different from flying in a jet, and modern marriage has only superficial similarity to what went before. Just as we embrace each new mode of travel that enhances human welfare, no one should mind adapting marriage to the needs of modern people.
Extending matrimony to same-sex couples advances the same interests cited in support of heterosexual marriage: encouraging stable commitments, offering a framework for procreation and upholding the interest of children in a legally protected family. If male-female marriage is good for straights and society, it's hard to see how same-sex marriage can be bad for gays and everyone else.
Conservatives shouldn't think of the change as a repudiation of the past. They should think of it as starting a new tradition.