Some commenters in the public-sex-and-nudity threads expressed puzzlement that we'd even discuss what for them is such an obvious question. One obvious reason for discussing it is the possibility that the current legal rule gets it wrong; but these commenters dismiss this possibility. And perhaps they're right -- I do tend to think the current legal rule is right, though I'm not nearly as certain as some of the commenters seem to be.

Yet even if one is sure one knows what the right answer is, exploring the reasons for that answer proves to be quite important. Let me just briefly identify a few:

1. Understanding the reasons for a rule helps us understand the boundaries of the rule. Even if we agree with the core principle that sex or nudity in most public places should be outlawed, this core agreement may not extend to all the boundary cases. Should nude beaches and nudist colonies be entirely forbidden? Should female toplessness be generally allowed on many beaches, as it is in places that aren't that far from us culturally? Should near nudity (at least off beaches) be forbidden, as some have at times suggested even in the U.S.? Should nudity be forbidden on broadcast television? On cable television? The list could obviously go on.

2. Relatedly, understanding the reasons for a rule helps us evaluate analogies that people draw to the rule. Whether two situations (e.g., public nudity and smoking on public streets) are analogous requires us to understand the morally and practically salient features of each situation. If public nudity should be banned because it's immoral for a person to appear nude before strangers, this wouldn't itself carry over to smoking. If it should be banned because people are entitled to walk the street free of perceiving things they find offensive, then the question should just turn on what the majority finds offensive (even without regard to health questions). Likewise, is public nudity analogous to the display of "classical-looking" nude statues, so that we could prohibit the latter as we prohibit the former? Hard to tell without understanding why it is that we think public nudity may properly be banned.

3. Understanding the reasons for a rule may also help us understand how harshly violations of the rule should be punished, and how much effort we should invest in enforcing the rule.

4. Understanding the reasons for a rule can help us think about theories that would reach results contrary to the rule. For instance, if some libertarian theory tells us that public nudity and sex should be legal, but we're convinced that this result is wrong, then this tells us that the theory is mistaken. But how mistaken, and in what ways? Is the error of the theory a deep mistake that should lead us to jettison the whole theory? Should it lead us to recognize an exception to the theory, and if so, what sort of exception?

I understand the pragmatic impulse not to worry about problems that seem to have an obvious answer. But it seems to me that thinking hard about reasons, even for the seemingly obvious results, is potentially quite valuable, and shouldn't be lightly pooh-poohed.