So I'll repeat the question: can you state your real argument in favor of gay marriage?
Note: I'm asking why you favor it, not why you feel it is politically feasible.
Why are you trying to bring his personal opinions into play?
Sp332 and myself want to hear an argument for gay marriage which does not logically lead to legalized polygamy. Aristus is arguing that gay marriage will not politically lead to legalized polygamy.
"Marriage is an institution with the primary purpose of providing a good environment for children and their biological parents. We only permit sterile straight couples to get married to promote the illusion that marriage is about love and happiness for the married couple. Since a polygamous household is not a good environment for children, we ban polygamy."
Continuing in the tradition of stating opinions that are not ours but are potentially interesting:
One could argue that at the time these laws were made, checking for sterility was impossible and is now potentially prohibitive or inaccurate as medical science improves.
The most one can do is show that some more generally accepted subjective value implies the a specific subjective value. A more general argument: "any act performed in private between consenting adults is morally acceptable. This implies gay sex is OK."
(That's also a specific example of a general argument which most proponents don't actually believe. See this comment thread for an example: http://news.ycombinator.com/item?id=806581 )
2) State-recognized marriage is not a right. Like copyright, it is the granting of certain privileges, at the expense of the state, with the expectation that the state will benefit. You have a human right to write books and songs, and you have a human right to choose a partner. Separately, the state may have laws to encourage those things. A law recognizing gay marriage is not saying "you're equal with everyone, you can drink from the same water fountains." It's saying "we encourage gay marriage. We want to incentivize it." What is the case for that? Seems like it should be a sociological, economic one.
2) Yep. In this case I mean rights as in "water rights" as opposed to higher-order natural rights. Pragmatic reasons to encourage gay marriage are largely the same as for regular ones: married people live longer and are generally more happy. Stable households mean stable communities. Sensible distribution of estates. More homes willing and able to adopt the millions of kids who need them. Etc. Procreation is not the entire or even the most important reason to encourage households.
Unfortunately those arguments don't hold water with people who think being gay is immoral in and of itself.
Any society that accepts and encourages gay marriages is committing suicide.