Suppose that the state's only interest in promoting marriage is to encourage and support procreation. Take that as a given for this argument: you might not agree with that, but that's the position some people take. So given that, the state has NO interest in promoting SSM's, since they aren't involved in procreation...
So your question should be not why doesn't your marriage pose a threat (it doesn't), but why would the state encourage your marriage when it has no interest in it?
... [T]he state is not capable of distinguishing between a marriage like yours where you have chosen to remain childless and a marriage which produces children... The state should not try to draw a dividing line between different classes of heterosexual couples because it is not qualified or capable of making such a distinction. But the distinction between a heterosexual couple and a homosexual couple is pretty obvious, and the state IS capable of making that distinction.
Interesting theory that you are putting forward -- that it is a
lack of desire to support non-procreative marriage, rather than
active hostility to same-sex marriage, which is at the root of some significant portion of the opposition. Let's see if we can test that theory out.
You explain away the lack of opposition to marriage in which the couple has no desire to procreate, on the grounds it would be too difficult and too intrusive to determine which couples do and do not genuinely wish to procreate. Okay -- let's set that aside. You explain away the lack of opposition to marriage of infertile couples on the same grounds, that it would be too difficult and too intrusive to identify them. Again, okay -- let's set that aside.
But there is one heterosexual category for which this is not a problem: the elderly.
We know there is a
minimum age below which people are legally forbidden from getting married. For the purpose of this discussion, let's consider a proposal to establish a
maximum age of 65 as well. As someone who who believes marriage is about more than procreation, I oppose such a restriction. But those who believe that "the state's only interest in promoting marriage is to encourage and support procreation" should be as supportive of a ban on over-age marriage as they are on same-sex marriage.
(a) Women past menopause generally cannot become pregnant, so people who are only interested in supporting marriage where procreation is a possibility should have no interest in supporting the marriage of post-menopausal women. (b) As people age, the quality of the eggs and sperm they can contribute to an act of procreation deteriorates, so children born to older people are likely to be significantly less healthy than children born to unions of younger people. (c) Elderly people are likely to die, or suffer severely reduced physical and mental capabilities, before a child they create in their later years has grown to maturity. So if encouraging and supporting procreation is the state's only interest in promoting marriage, then there is no reason for the state to support marriage by people over 65.
If an amendment were proposed to the next "protection of marriage" bill to ban over-age marriages in addition to same-sex marriages, it would seem that people who oppose same-sex marriage for the reason you suggest should have no objection to the amendment. (Indeed, it would seem they should be happier with the bill with that amendment than without.)
If such a rider were attached to one of the current anti-gay-marriage bills, do you believe that people supporting the unamended bill form would continue to support it in amended form? Or do you believe (as I do) that most would fight against such an amendment being added and would, if the amendment passed, oppose the passage of the amended law?
If opponents of same-sex marriage people supported the amendment (and the amended law), that would indicate you are right in your supposition of the reason for their opposition to same-sex marriage. If they opposed amending the law in this way, and opposed passage of the law if such an amendment were added, it would indicate you are wrong in your supposition.
Unless some group pushes for such an amendment to one of these laws, we probably won't get to see in real life how many proponents of these "marriage protection" acts truly are concerned with supporting procreation and how many are simply using that as an excuse. But even in the absence of such a proposed amendment, there is a simple way to test your supposition.
If there are indeed a significant number of opponents of same-sex marriage whose opposition is rooted in
support of procreation rather than in
antipathy to homosexuality, then it should not be difficult for you to find people who are willing to say they would support such an amendment. Can you give me the names of five members of Congress -- either the Senate or the House -- willing to say they would support such an amendment? The names of five state legislators? The names of five spokespeople for grass-roots groups working to pass "marriage protection" laws who would support such an amendment? Or just two prominent members of the Bush administration willing to speak out in support of it?
If you can pass any
any of those tests, I will agree you have a valid point. Until then, the evidence indicates to me that it is animosity toward homosexuals rather than interest in procreation which is the main motivation to ban same-sex marriage.