Soundness, Validity, and Gay Marriage

"Anybody who has several sexual partners in a year is committing spiritual suicide." Catchy first line, huh? It's funny when I read columns that start like that, and conclude with a controversial suggestion that I agree with. I'm obviously pretty slow to note this, but there's an interesting column in last Saturday's New York Times. The conclusion is that conservative Christian supporters of traditional family values ought to support legalization of homosexual marriage.

Marriage is in crisis because marriage, which relies on a culture of fidelity, is now asked to survive in a culture of contingency. ... Still, even in this time of crisis, every human being in the United States has the chance to move from the path of contingency to the path of marital fidelity — except homosexuals. ... We shouldn't just allow gay marriage. We should insist on gay marriage. We should regard it as scandalous that two people could claim to love each other and not want to sanctify their love with marriage and fidelity.

I found this interesting for two reasons. First, because it's a very different argument than I'm used to hearing from the right, and second, because it's a good object lesson for validity and soundness of arguments, which I discussed a few days ago. Here's an oversimplified version of the argument:

1. Sex, including homosexual sex, outside of marriage is bad.
2. The more marriage, including homosexual marriage, there is, the less sex outside of marriage there will be. Therefore,
3. It is good to encourage homosexuals to marry.

The argument is valid -- if we accept (1) and (2), we must accept (3). Of course, it's only sound if (1) and (2) are both true. (2) is an empirical claim that seems likely. (1) is a value claim that I disagree with as a universal claim. So we have an unsound, valid argument, which also happens to have a true conclusion. Go team.