A recent flier sent to my house urged me to vote for Measure 36, a state constitutional amendment which would define marriage as being between one man and one woman. A recent Oregonian article also laid out the reasoning for the supportes of Measure 36. Similarly, Sozo in a comment to my previous post also laid out a defense of traditional marriage. All three said the same thing: children are better off with a mother and a father.
This is, of course, a complete non-sequiter.
The reasoning is that if you outlaw gay marriage, then you will not have gay couples parenting children. But that is patently untrue. Gay unmarried couples currently have children (whether through adoption, or IVF, or from previous heterosexual encounters). Preventing such couples from getting married will not magically make those children go away. All that it does is deprive those children of the stability of a legally recognized family structure.
Futhermore, if you were to follow this logic to its end, then you would outlaw all forms of single parenthood whether it be through divorce, death of a spouse, or the parents never getting together to begin with. Interestingly, it seems to validate living-together without getting married.
As a side note, the veracity of the statement "children are better off with a father and a mother" is currently in debate. Experts on both sides agree that longer-term studies are needed to decide the issue. All they know so far is that there are differences in how the children are raised when raised by gay parents, but it is not yet clear if the differences are harmful in comparison to being raised by heterosexual parents. So far the evidence leans toward it just being different but not harmful, but more work needs to be done.