DEAR MISS MANNERS: The custom of taking hats off indoors seems to be disappearing. Even in church and classrooms, I am increasingly seeing hats (baseball caps, especially).

It would be rude for me to tell all these people to remove their hats, but as a parent, I can enforce this etiquette rule with my own children. And as a teacher, I can enforce it in my own classroom.

My problem is when I am asked, "Why? No one else asks me to take my hat off. Why is it important?" These young minds are not satisfied with the answer of "because it is the proper thing to do."

I've been telling them that when you wear your hat inside, it gives the impression that you are in a hurry to leave. That makes your host (or teacher) think you don't want to be in their company, and that would be rude.

Can you help me with an improved or more complete response? Or is it really not important after all, and I should just let these young people blend in with the hatted crowd?

GENTLE READER: While appreciating your efforts to teach courtesy to your pupils and your children, Miss Manners is grateful to have the opportunity to help you do so on a deeper level. Otherwise, you may get some difficult questions.

What if a Jewish student says that he (but not his sister) has to cover his head in his synagogue as a sign of respect? What if a Catholic student says her grandmother remembers when she (but not Grandpa) had to cover her head in church? What if students report examples where it would be improper, whether for cultural or religious reasons, not to wear turbans or scarves?

"Aha!" the brighter pupils will declare: "This shows that all these rules are arbitrary." And they would be right.

But -- here comes the deeper lesson -- that does not mean that a given society's customs may be ignored with impunity. Symbols are always arbitrary, but can nevertheless carry great emotional weight. A hat on -- or off -- could be extremely offensive, given the setting and circumstances.

Now we complicate things even more by introducing a time and gender element. The traditional American rule was that gentlemen must remove their hats indoors. But for ladies, wearing a hat indoors -- at a luncheon, for example -- was proper. (Girls may try to use this to claim they can wear their baseball caps in class, but no, this does not apply to unisex and/or athletic gear.)

Are any of these rules still in effect?

Morality-based rules remain valid no matter how many people disobey them, just as the prevalence of crime does not make it legal. But symbolism only works when the meaning is generally recognized.

Miss Manners hears from Gentle Readers who object to violations of those hat rules, so she believes the code is still being read. But it would be an interesting research project for your students to find out.

You will have to teach them that the question is not whether people approve of these rules, but whether they are even aware of them; that they should ask the question in a non-prejudicial way; and that they should ask people of different ages.

Miss Manners apologizes for making more homework for you.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)