In many respects, "Civil Unions" in California are very similar to marriage - but there are many areas where it's unclear how a civil union should be treated. I suppose a huge part for the reason for wanting same-sex marriage is psychological - wanting the respectability that marriage gives to a union. Opponents often say, "they can have all the rights they want, as long as they don't call it 'marriage.'" I don't know how often I've heard people say, "Why can't they just call it by another name?"

I think the main reason for opposing gay marriage is the same as the main reason for supporting it - the term "marriage" gives respectability, and helps to ensure that society treats a married couple like a family, not just partners in a legal relationship.

-Joe-