Will Baude has some interesting arguments against presexual marriage. Go ahead and read that again to make sure you got it right. For those having trouble figuring out this concept, he means that he doesn't think you should marry someone without first having sex with them, especially if you have a strong disfavorable attitude toward divorce.
His first argument is quite poor. "It would be bad to be stuck married to somebody whose views about the purpose and details of sex were drastically different from one's own." Ok. I agree. My wife and I had whatever such conversations as are necessary before getting married, and we didn't need to have sex to do so. I think this argument vastly underestimates the value of communication and understanding of the other person when it comes to sex.
The second argument is that sex is an important form of understanding someone. I agree. Then he somehow thinks it follows that "when something resembling eternal commitment is at stake, it's hardly wise to leave this chapter unperused". I don't see how you need to know every detail of someone before making a commitment for life. (I see no reason to think marriage is permanent. As marriage vows indicate, it ends at the death of whichever spouse dies first.)
There are some things you can't know until after you've been married for years. I'm not sure why you need to know how someone will be in bed beforehand. People who think you do just have no notion of growing to know someone, learning to appreciate things you might not initially understand, and growing to learn how to be better at everything you do. Why should it be different with sex? I don't see why any couple can't learn to be very good at serving each other sexually.
He challenges the notion that permanent monogamy can be natural by giving the simple evidence that not everyone holds that view. Apparently he has little sense of the varieties of what people might mean by 'natural' in this context. The usual sense is that there's a purpose for sex, not one necessarily observable by watching what happens, especially if it's a religious idea having to do with God's purpose for creating sexual unity between a man and a woman. This argument also ignores the Christian view of the fall, which masks numerous truths about the world that conflict with sinful desires. If such a state is real, then what people consider natural would be a very bad guide to what is natural. So the argument has little force against its intended audience.
I have only one positive thing to say in favor of the view he's challenging. He says "When I was taught about sex in school they warned us that once sex enters a relationship for the first time, everything changes. That isn't always true, but to the degree that it is, I think people should get married knowing what they're getting into rather than taking a random draw."
This seems to me to be a reason for the opposite of what he's saying. Consider also a statement he makes in his earlier post: "And sex can also build attachments between unmarried people (one does not forget one's first lover). Morse herself says that 'Science can now tell us how the hormones released during sex help to create emotional bonds between the partners.'"
It seems really funny for me to see someone acknowledge all this and then think that it should be perfectly fine to have sex with someone and then think that there's no presumption of continuing in the bond you've started. I have a hard time thinking of a breaking of the deep spiritual connection that goes on in sexual union, whether in marriage or outside it, as anything other than violence. The psychological evidence seems to support this. When I teach this material in an ethics class, my students seem to understand very clearly the view that sexual relations involve a union in spiritual ways that we can't put into words. They don't necessarily see it as harmful to have multiple sexual partners, but they do understand the argument that it's just plain not the best sex to be dividing oneself in promiscuity. When you combine this with the moral ideal of seeking what's best, there's a strong presumption against so dividing yourself sexually.
The view I see in the Bible is that once you've had sex with someone you really are spiritually married to them, whether you've legally acknowledged it or not. This view seems much more plausible at this point. Then breaking that bond by marrying someone else is tantamount to divorce, which is a violence that I think deserves strong moral condemnation. (The idea here is that people were too liberal when they thought you should get married when you conceive a child, i.e. when you're caught. The fact that you've had sex is enough reason for at least a presumption that you will get married, since you've already committed yourself on the most intimate level physically and are just breaking your own commitment by not doing so in a legal way. I should say that there may well be reasons that outweigh that presumption.)
Not everyone will follow all the steps in this argument, and so I agree with Baude's point at the end. "I think that we ought to be broadly tolerant of the fact that people we otherwise respect a great deal have vastly different views than us about sex.... I don't think that all views about sexual relationships are equally valid." It's nice that he recognizes this. Most people I know with views similar to mine are highly tolerant of those with more liberal views about sex, but many of those they tolerate frequently accuse more conservative people of intolerance, often with such venomous language that I have a hard time seeing as tolerant. It's refreshing to see someone not so two-faced about it.