> There is a substantive difference between the sexes
> that could rationally limit what combination should
> be allowed to get married
Interesting. Could you expand on what those differences are, that might yield rational reasons?
Also, please could you let me know if they extend to: couples where one or both are infertile; couples where one or both partners have a genetic intersex conditions, such as Klinefelter syndrome; couples where one or both partners had gender reassignment shortly after birth due to medical intervention; couples where both partners are living as men, but one was born female, but no surgery has been performed; as the before, but surgery has occurred; couples where medical accident has led to removal of genitalia; completely asexual male/female couples who have decided they wish to live together and support each other.
Lets clarify some terms: by marriage I mean the institution recognized by government. Of course, anyone can get "married" to anything they want--it just wont be recognized by government.
The government has an interest in promoting social policy it believes is a benefit to society, by way of its power of taxation. It is not entirely unreasonable to believe that society is better served with the family unit being anchored by one man and one woman, and thus believe that government benefits should be limited to this "ideal" case.
Personally I don't care one way or the other, but I don't entirely dismiss this idea either. I am hardcore "evolutionist", in the sense that I believe there is hidden value in the way things have played out over the eons. The fact that we evolved distinct sexes and sexual dimorphism is not something to be dismissed as an accident of history. There is information encoded in these facts that may not be readily discernible from our vantage point, but it is there nonetheless (just like there is practical information encoded in various culture's scriptures against eating pork). I do believe society is better off with the "traditional" family unit as its cornerstone, and so government reserving benefits for this traditional unit does make a certain amount of sense. I don't think the benefit is big enough, nor do I care enough, to try to deny people the symbolic label and a handful of tax-breaks though. But framing the issue of marriage as a civil rights issue has always seemed a little absurd to me.
Also, please could you let me know if they extend to: couples where one or both are infertile; couples where one or both partners have a genetic intersex conditions, such as Klinefelter syndrome; couples where one or both partners had gender reassignment shortly after birth due to medical intervention; couples where both partners are living as men, but one was born female, but no surgery has been performed; as the before, but surgery has occurred; couples where medical accident has led to removal of genitalia; completely asexual male/female couples who have decided they wish to live together and support each other.
Also any links to your research in this area.