The Fate Of Gay Conservatism, Ctd

Video re-posted from earlier today (podcast available here). A reader writes:

I watched your appearance at the Cato Institute in which you came to intellectual fisticuffs with Maggie Gallagher.

There was one point of debate on which I felt you had a strong argument against Maggie that you didn't use: Maggie was constantly trying to throw gay marriage off the table, and yet continued to put it back on the table herself, particularly when she referenced supposed violations of religious conscience related to laws that restrict discrimination by institutions whose religious beliefs define marriage as between a man and a woman.  In the context of that debate, she mentioned that part of what makes the traditional definition of marriage sacrosanct is that only a union between a man and a woman can produce new life.

I wonder why didn't you ask her: how does allowing homosexual marriage diminish the ability of heterosexual marriage to produce life?

Her response could've been nothing credible. The only way it would diminish the life-producing aggregate of heterosexual marriage is is heterosexual divorce rates go up after homosexual marriage becomes the law of the land.  And in every state where same-sex marriage is legal, divorce rates have either stayed level or actually dropped.  In fact, divorce rates are higher in states with outright bans on same-sex marriage.

I believe in the end, this is an argument about justice: in order for an injustice to be committed against a person or group of people, there has to be an injury.  Where is the injury to heterosexual marriage here?  How is the ability of a heterosexual marriage to produce life diminished in any way by granting same-sex couples the right to marry?  What is the injustice she claims exists?
Her citing public opinion is also interesting: public opinion about racial discrimination in many states was in the majority favoring discrimination prior to Brown vs. Board.  Does that make segregation historically correct in her eyes?  She may think it impolite to compare traditional marriage to racial discrimination, but she cannot avoid this question if she intends to be intellectually consistent: if she believes that public opinion polls should inform questions of social equality, she must necessarily believe that the majority support of segregation laws in many Southern States prior to Brown v. Board vindicated the policy of segregation. If on the other hand, she believes segregation was unjust, then she cannot reasonably use public opinion polls as an argument for her position; the majority has been wrong on questions of social justice in the past, so it ill suits anyone to rely on polls to vindicate their beliefs. As she said herself: she was Conservative when it was unpopular to be so.  To fight against public opinion when it opposes you and martial it to your aims when it is with you is not intellectually honest.
One last thing:  public opinion is often biased towards the status quo and easily manipulated by changes of public policy.  A generation after Loving V. Virginia was decided, people who grew up with inter-racial marriage being the norm no longer question it.  in fact, they take it for granted as something that anyone ought to be able to do.  This wasn't always the case.
So the final nail in the coffin for Maggie Gallagher is this: if same-sex marriage is legalized across the nation, and it remains so for the next several decades, a generation of Americans will grow up "with" same-sex marriage, just as a generation grew up in desegregated schools after 1954; and just as a generation grew up with inter-racial marriage after 1967.  We no longer question whether these decisions resulted in a more just society.  Yet at the time, they were extremely contentious.  This means, yet again, that public opinion is a terrible indicator of whether or not a policy is correct or just. It simply reflects the biases of a generation toward the status quo.
Until Maggie can answer as to what injury same-sex marriage causes to the "life-creating" potential of heterosexual unions (she can't), or is willing to come out in support of publicly supported segregation laws as vindication of her appeal to opinion polls in support of her position, she will be unable to make a convincing moral case against same-sex marriage; and indeed she can't, because there is no injury to speak of that would make same-sex marriage unjust to heterosexuals.