What, then, are the justifications for California's decision in Proposition 8?
The explanation mentioned most often is tradition. But simply because something has always been done a certain way does not mean that it must always remain that way. Otherwise we would still have segregated schools and debtors' prisons. ...
The second argument I often hear is that traditional marriage furthers the state's interest in procreation—and that opening marriage to same-sex couples would dilute, diminish, and devalue this goal. But that is plainly not the case. Preventing lesbians and gays from marrying does not cause more heterosexuals to marry and conceive more children...
This procreation argument cannot be taken seriously. We do not inquire whether heterosexual couples intend to bear children, or have the capacity to have children, before we allow them to marry. We permit marriage by the elderly, by prison inmates, and by persons who have no intention of having children.
Another argument, vaguer and even less persuasive, is that gay marriage somehow does harm to heterosexual marriage. I have yet to meet anyone who can explain to me what this means. In what way would allowing same-sex partners to marry diminish the marriages of heterosexual couples?