[I think that title means "the splendor of logic" but I'm shaky on making adjectives in Latin.]
I recently posted an article on my Facebook about a movement of mostly Catholic university students campaigning for traditional marriage in Maryland. I included the following quotation in my link:
Shortly after setting up at a busy intersection, reactions erupted from passing traffic. All sorts of reactions -- honks of approval, thumbs up, double thumbs up, and applause. Then there were some who let out ghastly strings of insults, all in the name of “tolerance.” Why did they insult us? Because our banner stated this truth: “God’s marriage = one man + one woman.”
I cannot be sure without asking, and I don't want to ask, but I believe this prompted a friend of mine––call her Ariadne––to update her status with a kind of rebuttal:
So, let me get this straight...Charlie Sheen can make a "porn family", Kelsey Gramer can end a 15 year marriage over the phone, Larry King can be on divorce #9, Britney Spears had a 55 hour marriage, Jesse James and Tiger Woods, while married, were having sex with EVERYONE. Yet, the idea of same-sex marriage is going to destroy the institution of marriage? Really? Re-post if you are proud to support equal rights.
Amidst the welter of "Like" votes and supportive comments, one person was kind enough to point out the logic here is a bit… off… although she didn't elaborate. Allow me to elaborate.
Let's formalize Ariadne's argument:
Supporters St of traditional marriage t (i.e. heterosexual monogamy) believe homosexual marriage h undermines/destroys the institution of marriage m.
The behavior of many St actually undermines/destroys m.
Therefore the arguments of St against h are invalid.
This is a weepy ad hominem fallacy, with a splash of emotive tu quoque. Let's run the argument in a parallel scenario:
Supporters Sh of honesty h believe lying l undermines/destroys the goodness of human communication c.
The behavior of many Sh actually undermines/destroys c.
Therefore the arguments of Sh against l are invalid.
Supporters Sr of reforming the (USDA) food pyramid r believe the conventional food pyramid p undermines/destroys optimal human health h.
The (gustatory) behavior of many Sr actually undermines/destroys h.
Therefore the arguments of Sr against p are invalid.
I'll run two more versions, just because it's fun:
Supporters Sl of a law enforcement agencies l in society believe legal anarchy a (?) undermines/destroys the goodness of social harmony s.
The behavior of many Sl actually undermines/destroys s.
Therefore the arguments of Sl against a are invalid.
Suporters Sm of Western medicine m believe heavy drinking and smoking ds undermine/destroy optimal human health h.
The behavior of many Sm actually undermines/destroys h.
Therefore the arguments of Sm against ds are invalid.
I hope you see how poor this reasoning is.
"I've seen lots of NBA players miss shots from the three-point perimeter, so it's not an NBA rule that you have to make three-pointers from that line. You can make three-pointers from anywhere on the court, as long as you don't hurt anyone and you really, truly, sincerely intend to make a three-pointer. Re-post this if you are proud to support equal shooting rights in the NBA."
That's the level of logic we're dealing with here.
If proponents of traditional marriage based the nature of marriage on the quality or performative excellence of its "practitioners", then Ariadne's argument would be valid and sound. (A stronger argument would be to say that, since supporters of traditional marriage cannot agree, even among themselves, on a single definition or policy for marriage, there's not even a coherent case for traditional marriage.) Instead, the defense of traditional marriage––nay, the defense of marriage itself––rests on the principles of social and biological fruitfulness and order. When heterosexuals sin against that order by "doing marriage" so poorly, they eo ipso underscore the intelligibility and dignity of marriage. Indeed, defenders of homosexual marriage like Ariadne invoke the examples of bad heterosexual marriages because they implicitly agree those couples failed to live up to what marriage is, namely, lifelong monogamy between heterosexual partners.
Interestingly, while writing this post, I learned of a fallacy I had not known before: the argument from fallacy! (I call it the fallacy fallacy.) This fallacy occurs when A rejects the conclusion cb of B's argument b because b is dialectically fallacious. Showing that b is fallacious does not, however, suffice to show cb is false, since only an argument that cb is false would demonstrate ~cb. Hence, I am not saying that, because Ariadne's argument is fallacious, therefore homosexual marriage is wrong; doing so would mean I commit the fallacy fallacy. Rather, all I have done in this post is show that her argument against traditional marriage is fallacious and does not suffice to show the rightness of homosexual marriage and certainly doesn't suffice to invalidate defending traditional marriage.