I think Gallagher's view is something like this: If you're too explicit about marriage (as a civil, legal institution, anyway) being just about regulating procreation, it loses the mystique that pulls people into it. So you can't just reserve the institution for people who have or are having children. Marriage, on this account, is a little like the "here comes the plane, flying into the hangar" game you play with an infant when you want him to eat his strained spinach. If you're too overt about the function of the game, it won't serve that function.As Julian notes earlier in the post, the argument has the form of a Noble Lie: people have to believe one thing in order for them to achieve something else.
On the other hand, if you allow too explicitly that marriage can also be centrally about love between two adults, it becomes obvious that this may not be best served by marrying the first person you have a child with. What Gallagher and company want to preserve, in other words, is an ideal that links personal romantic fulfillment and childrearing. If we start analyzing too closely, of course, it become apparent that these things won't necessarily go together. The function of marriage, then, is to create the illusion of a necessary unity between two logically distinct elements: one functional or utilitarian, the other romantic or spiritual. And the reason gay marriage opponents so seldom put it in quite this clear a fashion is that to speak openly about the importance of preserving an illusion is precisely to concede that it is an illusion, which is what you were trying to avoid. [boldface emphasis added]
I’m less hostile than Julian to the concept of a Noble Lie (though in the case of marriage I don’t think one is really necessary). I think, for instance, that utilitarian goals are best achieved if people don’t approach social issues from a utilitarian perspective as a matter of course, but instead generally start from some notion of rights or personal autonomy. But with any Noble Lie, there is always the danger of the truth getting out. And once the genie is out of the bottle, the first-best outcome – the one whose achievement depended on the perpetuation of the Lie – may no longer be an option.
The Noble Lie in the realm of social choice has an analog in the realm of personal choice: self-deception to achieve goals that cannot be sought directly. Probably the best example is the desire to be surprised. If you try to be surprised, you probably never will. Or you might be surprised sometimes, but no more (and probably less) often than if you didn’t try. So if you want to be surprised, your best strategy is to distract yourself with other activities and do your best to forget about your desire for surprise. But there is a danger, at least for the mentally active, of infinite regress: if you choose not to try to be surprised so that you’ll be surprised, then you actually are trying to be surprised... It’s like trying not to think. If you’re thinking about the fact that you’re not thinking, then you’re still thinking.
Trying to be surprised is not the only example. Suppose you’re interested in meeting members of the opposite sex. If you try to do this deliberately, you’re likely to send off a strong creepy vibe that will stymie your efforts. So you’re better off doing something else – you know, just hanging out with friends, having fun, in a place where there might happen to be people worth meeting. But hold on: if you know that’s the real reason you’re hanging out, then that old creepy vibe can creep right back in. You’ll be most successful at meeting members of the opposite sex if that really isn’t your purpose. If that’s not a genuine paradox, it’s close.
What’s my point? Well, somehow we manage, imperfectly, to overcome these personal choice paradoxes. People who like surprises do get surprised, and people who want to meet members of the opposite sex quite often do. How? I’m not sure, but I think the mechanism is a kind of mental compartmentalization. We develop rules of behavior and habits of mind that put us in the sort of situations where (we hope) we’ll get the things we want – and then we forget about it and just fly on autopilot. The internalized rules and habits take on a life of their own, and that’s often a good thing. Perhaps the same kind of process, on a social level, can help preserve Noble Lies that are actually worth preserving.