I want to promote this idea out of the comments thread from the previous post.
For those who (understandably) didn't read my long entry from last night, the gist of Charles Cooper's pro-Prop-8 closing argument, such as it was, was that (a) the state's primary purpose in encouraging opposite-sex marriage is to prevent accidental out-of-wedlock pregnancies; and therefore (b) the state shouldn't allow same-sex couples to get married, because they can't have accidental pregnancies.
In the course of making this argument, he noted that it was in the state's best interest for even infertile opposite-sex couples to get married, because it reduces the likelihood of kids being born out of wedlock:
[...] the fertile member of that couple will be less likely to engage in sexual relationships with third parties and raise anew a threat of some type of unintentional or what I have been referring to previously as irresponsible procreation.
Commenter Zim pointed out this morning that this argument applies equally well to bisexuals.
Because (paraphrasing Zim):
Consider a same-sex couple where one member of that couple is bi.
If that couple gets married, then the bi member of that couple “will be less likely to engage in sexual relationships with third parties” of the opposite sex, and to thereby risk an out-of-wedlock accidental pregnancy.
Therefore, the logical conclusion of Cooper's argument is that, just as the state encourages infertile couples to marry, the state must encourage bisexuals to marry, regardless of the gender of the person they marry.
Glad to hear you're in favor of at least some same-sex marriages, Mr. Cooper!
(I realize that this issue was a side point in Cooper's argument; I imagine he would find some way to drop this bit if he had to. I also realize that his whole argument is a tissue of illogic, so attempting to draw logical conclusions from it is probably pointless. But I was entertained enough by Zim's idea that I wanted to draw more attention to it.)